1 Introduction
Compared with traditional crystalline materials, amorphous materials are a class of solids that lack long-range periodic atomic arrangement and constitute an extremely important and ubiquitous form of condensed matter
［1-8］. From ancient glass and amber to modern rubber and asphalt, as well as newly emerging material systems such as metallic glasses, amorphous polymers, and amorphous nanomaterials that have attracted widespread attention, amorphous materials, owing to their unique microstructure and the resulting superior properties, play an indispensable role in cutting-edge fields such as energy, information technology, and biomedicine
［9-13］.
Compared with crystalline materials that exhibit highly ordered atomic arrangements, amorphous materials exist in a thermodynamically metastable state. Their long-range structural "disorder" directly results in physical and chemical properties that differ significantly from those of crystals, such as isotropy, highly unsaturated coordination, the absence of grain boundaries, and high corrosion resistance
［14-20］. This unique structure–property relationship makes in-depth research on amorphous materials not only of significant theoretical value but also endowed with substantial potential for practical applications
［21-23］.
Despite the widespread applications of amorphous materials at present, the intrinsic nature of their microstructure and the precise elucidation of the "structure-property" relationship remain major challenges in the field of condensed matter chemistry
[24-27]. The core difficulty lies in the fact that conventional crystallographic structural characterization techniques based on symmetry and periodicity are no longer fully applicable to amorphous systems
[28-31]. Therefore, clarifying the interaction mechanisms among structural units at the microscopic scale-specifically the nature of covalent, ionic, and metallic bonds, as well as the contributions of intermolecular forces such as hydrogen bonding and van der Waals interactions-is fundamental to understanding the formation and associated properties of amorphous materials, and will significantly advance our comprehension of condensed matter systems
[11, 32-35]. In light of this, this paper first systematically examines the structure and properties of inorganic amorphous nanomaterials, analyzing from a microscopic perspective the formation and stabilization mechanisms of amorphous states. Subsequently, focusing on more macroscopic applications, it elucidates how the structure of inorganic amorphous nanomaterials determines and influences their mechanical, optical, and electrical properties, as well as their critical roles in catalytic and corrosion-related chemical reactions. Building upon these insights, the study adopts a multiscale structural viewpoint to delve into the electronic structure, various types of defects, and the intrinsic role of the amorphous structure itself in chemical reactions, aiming to establish a "structure-activity" relationship. Finally, the paper offers a prospect of future research directions and application prospects for amorphous materials, with the goal of establishing a systematic reference framework for the further development of high-performance amorphous materials and providing valuable insights for a broader understanding of condensed matter structural chemistry.
2 The Concept of Amorphous Materials
Unlike crystalline materials with a traditional atomically ordered arrangement (Figure
1A,
1C), amorphous materials are solids in which atomic/molecular structural building blocks do not exhibit long-range spatial periodicity (
Figure 1B)
［1］. Consequently, solids in the amorphous state can only display limited order based on specific chemical units within a length scale of several atoms or molecules (
Figure 1D). This implies that amorphous materials possess short-range order (<1 nm) but exhibit complete disorder at larger scales (>2 nm). Research on this class of special-structure materials will greatly enrich the research content of traditional materials science and further advance the field of condensed matter chemistry.
Unlike crystalline, stable solid-phase materials, amorphous materials are often regarded as a metastable intermediate phase during the liquid–solid transition process. On a macroscopic scale, they possess a fixed shape characteristic of solid materials and exhibit rigidity and resistance to shear stress; however, their microscopic atomic arrangement resembles the disordered state of liquids. Therefore, amorphous materials can be considered disordered solids in a "frozen liquid" state. During the nucleation and growth processes of certain materials, amorphous materials with specific structures may form, where the precursors are viscous liquids, supercooled liquids, or disordered aggregates resulting from the aggregation and solidification of material building blocks. Under suitable conditions, these amorphous materials can undergo rearrangement of their constituent building blocks and eventually evolve into crystal structures with stable periodicity. Consequently, amorphous materials are widely believed to exist as intermediate states in the nucleation and growth processes of various materials.
Due to the inherent long-range structural disorder of amorphous materials, conventional diffraction techniques based on regular lattices (such as X-ray diffraction and selected-area electron diffraction) are not suitable for characterizing their structural features. However, by comparing the pair distribution functions (PDFs) of four states—gaseous, liquid, amorphous solid, and crystalline—one can further elucidate the structural characteristics of amorphous materials
［36］. The pair distribution function is defined as
g(
r) =
ρ(
r)/
ρ 0, where
ρ(
r) denotes the atomic density at a distance
rfrom an arbitrary atom (the statistical average), and
ρ 0represents the average atomic density of the material. This function quantifies the probability of finding another atom at a distance
rfrom any given atom; its variation with
rreflects changes in the atomic distribution at different distances centered on the reference atom.
Figure 2illustrates the pair distribution functions of the gaseous, liquid, amorphous solid, and crystalline states, along with their respective atomic distribution characteristics at specific moments.
(A) Gaseous substances: In a gaseous system, atoms are distributed completely randomly and possess a large mean free path. Within a range smaller than the interatomic spacing ar, no other atoms exist; therefore, g(r) = 0. Beyond the distance of ar, the atomic number density remains uniform at all spatial locations, and the probability of finding any atom is the same. At this point, g(r) = 1.
(B) Liquid Substances: Although liquid atoms are also undergoing random motion, stronger intermolecular forces limit their mean free path to a relatively short range. At the same time, liquid atoms are densely packed: the nearest-neighbor coordination number is typically 10–11, approaching a close-packed structure. In the region surrounding a central atom, the local atomic density ρ(r) exceeds the average density ρ0, but as the distance increases, ρ(r) gradually converges to ρ0. Consequently, the pair correlation function g(r) of a liquid initially exhibits a sharp peak as r increases and then decays to approximately unity. These characteristics reveal two major structural features of liquids: on the one hand, atomic random motion is quite vigorous, allowing atoms to diffuse disorderedly over a considerable range, resulting in a highly irregular overall distribution; on the other hand, strong interactions between neighboring atoms give rise to a higher local atomic density within a specific short-range region around a central atom (relative to ρ0). As the distance increases and intermolecular forces weaken, the atomic density gradually approaches the average value. Therefore, in liquids, the probability of finding nearest neighbors is higher than in a completely disordered system, indicating a certain degree of short-range orderliness.
(C) Amorphous Materials: The atomic arrangement in amorphous materials exhibits short-range order based on their chemical composition, with each atom having well-defined first- and second-nearest-neighbor coordination shells. Accordingly, the pair distribution function displays more distinct first and second coordination shells within a finite range around the central atom. However, due to long-range disorder, discernible peaks in the pair distribution function beyond the third coordination shell virtually disappear. It is noteworthy that the g(r) curves of the same substance in both liquid and amorphous solid states are highly similar; the only difference is that the first peak of the amorphous g(r) curve is sharper, indicating stronger short-range order. At the same time, the overall smoothness of the amorphous solid g(r) curve is lower than that of the liquid, revealing more structural details. This difference arises because atoms in the amorphous solid are confined to undergo thermal vibrations near their equilibrium positions—unlike those in the liquid, which can undergo large-scale translational motion—resulting in a significantly lower degree of isotropy in their atomic distribution compared to the liquid.
(D) Crystal materials: The atomic arrangement in crystals exhibits periodicity and symmetry, with other atoms existing only at specific positions located at a certain distance from the central atom. This results in a discontinuous distribution of g(r): extremely sharp peaks appear only at lattice sites, while the probability of finding atoms at non-lattice sites is always zero.
Amorphous materials, with their unique intrinsic structure, exhibit several characteristics that distinguish them from crystalline materials.
(1) Limited structural order: Amorphous materials exhibit local coordination regularity only within the first and second nearest-neighbor coordination shells (typically <1 nm), but lack discernible periodicity at larger length scales.
(2) Amorphous morphology: Due to its intrinsically long-range disordered structure, amorphous materials lack the self‑templating property of crystalline materials and cannot readily form well‑defined polyhedral morphologies through natural growth. Instead, they typically exhibit irregular morphologies or near‑spherical outlines driven by the minimization of surface energy.
(3) Diffuse diffraction pattern: The X-ray diffraction of amorphous materials exhibits a broad "hump" rather than sharp Bragg peaks, and selected-area electron diffraction reveals continuous diffraction rings. These are all typical characteristics of long-range structural disorder.
(4) Thermodynamic Metastability: The amorphous structure exists in a metastable state and, under high temperature or high-pressure conditions, tends to transform into a more stable crystalline state through structural relaxation.
(5) No fixed melting point and the presence of glass transition: Amorphous materials do not have a distinct melting point when heated; instead, they exhibit a glass transition without a constant-temperature plateau.
(6) Physicochemical Properties Isotropy: The overall structural homogeneity of amorphous materials results in isotropic mechanical, thermal, and electrical properties, which stands in stark contrast to the anisotropy commonly observed in crystalline materials.
3 Amorphous Structural Chemistry
Amorphous materials possess unique structural characteristics that confer macroscopic homogeneity and isotropy, in stark contrast to the anisotropy commonly observed in crystalline materials. Due to their disordered atomic arrangement, amorphous materials lack crystallographic defects such as grain boundaries and dislocations. This feature endows them with exceptional mechanical properties, including high strength, high hardness, excellent wear resistance, and superior fatigue resistance
［37］. Furthermore, the surface of amorphous materials is characterized by a large number of unsaturated coordination sites and dangling bonds; these highly active centers render them highly promising in the field of catalysis
［38］. Consequently, they can serve not only as ideal model systems for theoretical research but also as efficient and practical catalysts applicable to various reaction systems
［39］. Moreover, compared with crystalline nanomaterials, the substoichiometric composition and highly tunable electronic structure of amorphous materials are more conducive to enhancing their catalytic activity and selectivity
［3, 5, 40-45］. More importantly, the distinctive atomic arrangement inherent in the amorphous structure can optimize electron transfer and ion transport during chemical reactions
［27］, thereby endowing them with outstanding application potential in energy storage and conversion. Therefore, in-depth research on amorphous materials has not only advanced our understanding of the structure–property relationships in condensed solid-state systems but has also provided crucial theoretical and experimental foundations for the development of novel high-performance functional materials.
3.1 Interaction Forces in Amorphous Materials
Molecules are the fundamental units involved in chemical reactions. The properties of substances primarily depend on the characteristics of their constituent molecules, which, in turn, originate from the internal structure of these molecules. Therefore, the study of molecular structure constitutes a core theme in condensed-state structural chemistry and is crucial for understanding both the properties of condensed-state materials and the principles underlying chemical reactions. The central dimensions of molecular structure research encompass intramolecular chemical bonding and intermolecular interactions, both of which play a pivotal role in elucidating the forces acting within and between molecules. Amorphous materials differ fundamentally from crystalline solids due to their lack of long-range order; however, at scales below 1 nm, both types exhibit significant short-range order. This local structural regularity arises from strong chemical bonding interactions among neighboring atoms, which constrain atomic arrangements within specific chemical molecular units. Consequently, investigating chemical bonding and intermolecular interactions in amorphous materials can reveal their true roles in chemical reactions. This section will focus on the strong interactions among atoms within molecules—namely, covalent, ionic, and metallic bonds—as well as intermolecular forces such as van der Waals forces and hydrogen bonds, and will explore their respective roles and effects in amorphous materials.
The essence of a covalent bond lies in the sharing of electron pairs between atoms. These electrons are simultaneously attracted by both atomic nuclei, thereby forming a stable connection. Covalent bonds exhibit distinct directionality and saturation: directionality arises from the requirement that atomic orbitals achieve maximum overlap in specific spatial orientations, which directly determines the molecular geometry; saturation refers to the limitation on the number of covalent bonds an atom can form, dictated by its valence electron count and bonding capacity. In amorphous materials, covalent bonds, as a strong intramolecular chemical interaction, are widely present in various carbon-based materials, transition-metal oxides, and glassy systems. For instance, amorphous monolayer carbon has garnered considerable attention due to its unique physicochemical properties and broad application potential; however, the controllable preparation of heteroatom-doped amorphous monolayer carbon still poses significant challenges. This is because, in covalent systems, bond formation tends to occur at specific bond angles, while the relatively high bond dissociation energies (e.g., C–C bond: 346 kJ/mol; C–N bond: 305 kJ/mol; C–S bond: 272 kJ/mol) result in substantial reaction energy barriers, fundamentally hindering the large-scale atomic rearrangements necessary for the formation of long-range disordered two-dimensional amorphous structures. Recently, our research group developed a novel space-confined polymerization strategy that employs layered double hydroxides (LDHs) as templates to guide the radical polymerization of pyrrole within their interlayer channels
［46］. By confining planar polymerization within a rigid template, this approach forces bond angles to deviate and modulates the kinetic processes to lower the energy barrier, ultimately enabling the construction of two-dimensional amorphous covalent networks. Through the formation of sp
2 hybridized C═C bonds, we successfully fabricated nitrogen-doped amorphous monolayer carbon material (NAMC) with a discrete topological structure comprising five-, six-, and seven-membered rings. Electron microscopy results (
Figure 3A–C) reveal a uniform morphology with lateral dimensions exceeding 1 µm. The diffuse ring pattern observed in the selected-area electron diffraction (SAED) image confirms the amorphous nature of the material, whereas its single-layer thickness of approximately 0.7 nm indicates its atomically thin two-dimensional character. Annular dark-field scanning transmission electron microscopy (STEM-ADF) images show a one-atom-thick two-dimensional network composed of distorted five- to seven-membered rings coupled with eight-membered rings (
Figure 3D–E). Spatial confinement during the polymerization process inhibits C–C bond rotation and chain entanglement, thereby promoting the formation of a continuous amorphous monolayer with in-plane π conjugation. The C K-edge near-edge X-ray absorption fine structure (NEXAFS) spectrum exhibits a primary characteristic peak at 285.5 eV corresponding to sp
2 hybridized carbon (
Figure 3F), accompanied by a feature signal at 283.4 eV associated with topological defects such as five- and seven-membered rings, which is consistent with the STEM-ADF observations. This study not only demonstrates a solution-phase route for constructing all-covalently bonded two-dimensional networks but also provides a new methodology for covalent bond engineering, which can be applied to design two-dimensional polymeric materials with tailored architectures, such as polythiophenes and polycarbazoles.
Ionic bonds are generally formed through the complete transfer of electrons between electropositive metal atoms (such as elements in Groups IA and IIA) and electronegative nonmetal atoms (such as elements in Groups VIA and VIIA). They arise between oppositely charged ions and are characterized by a lack of directionality and saturation. Within spatial constraints, each ion attracts as many oppositely charged ions as possible to minimize the system’s total energy. Ionic compounds typically exist in crystalline form and exhibit high melting and boiling points. In amorphous nanomaterials, ionic interactions often go beyond the traditional simple electrostatic attraction paradigm, displaying dynamic and complex behaviors that are regulated by the local environment. The nonclassical nucleation process of calcium carbonate during biomineralization provides a compelling example: nucleation occurs via disordered precursors rather than through the addition of individual ions. Jin et al.
［47］proposed that hydrated bicarbonate ions undergo liquid–liquid phase separation to form a dense liquid phase, which subsequently transforms into hollow amorphous calcium carbonate nanoparticles. In this process, ionic interactions are modulated by solvation shells, stabilizing the Ca
2+⋅(HCO
3 -)
2complex and thereby enabling the existence of a metastable liquid precursor phase. The nanoscale confinement within droplets enhances the proximity among ions, accelerating the reaction while maintaining an amorphous structure. Acidic polymers, through interfacial interactions, further prolong the lifetime of the dense liquid phase, thereby regulating the reaction kinetics. This pathway reveals how, in amorphous systems, ionic bonding—through the synergistic effects of solvation, confinement, and organic modulators—can guide the formation of unique nanostructures.
Metallic bonding is the fundamental interaction in metallic and alloy materials, playing a particularly important role in disordered systems such as amorphous alloys. Its essence arises from the electrostatic attraction between positively charged metal ions—formed when metal atoms lose their valence electrons—and a “sea” of delocalized electrons that move freely throughout the structure. Unlike covalent bonds, which are directional and saturable, metallic bonds are non-directional and non-saturable. Metal cations tend to adopt close-packed arrangements in space (even in the amorphous state, short-range order is maintained), while the delocalized electrons are uniformly distributed, serving to bind and stabilize the cationic framework. The high mobility and delocalization of these free electrons give rise to the characteristic properties of metals, such as high electrical conductivity, high thermal conductivity, and excellent ductility. Even in amorphous metals lacking long-range periodicity, metallic bonds formed through electrostatic interactions between cations and electrons can still maintain macroscopic cohesion, providing a physical basis for understanding the mechanical properties, electronic transport behavior, and thermal stability of amorphous alloys. Based on an in-depth understanding of the relationship between metallic bonding and local structure in amorphous alloys, Yang et al.
［48］employed a combined approach of synchrotron radiation experiments and molecular dynamics simulations to systematically investigate the atomic structure of the Zr
70Ni
30- x Pd
x (where
x= 0–30) system. The study found that in the Zr
70Pd
30composition, the Zr–Pd bond length was significantly shorter than expected, being approximately 0.1–0.2 Å (1 Å = 0.1 nm) shorter than predicted based on Goldschmidt’s atomic radii and the reference bond lengths for the tetragonal crystal structure. The simulated structure factor S(Q) and the K-edge EXAFS spectra of Zr, Pd, and Ni were in excellent agreement with the experimental data for both Zr
70Ni
30and Zr
70Pd
30, thereby confirming the reliability of the structural model. To elucidate the mechanism underlying the bond contraction, the researchers compared the normalized Zr K-edge XANES spectra of this alloy series with those of high-purity Zr foil. The absorption edge of Zr
70Pd
30was observed to shift toward higher energies by approximately 1 eV relative to pure Zr, indicating enhanced Zr–Pd interactions and confirming that the shortened bond length results from the strong chemical affinity between these two elements. As a typical “soft” atomic pair, the strong bonding interaction between Zr and Pd significantly influences the local structural order and thermal stability of the amorphous alloy.
In addition to the strong intramolecular interactions between atoms, intermolecular forces are also frequently employed to construct amorphous materials
［17, 39, 49-51］. Intermolecular forces are weak interactions that occur between molecules or between charged regions within polar molecules. Their energies are typically below 100 kJ/mol, often even less than 50 kJ/mol. These forces influence macroscopic physical properties such as melting point, boiling point, solubility, and surface tension, without altering the chemical characteristics of the substance. Intermolecular forces are primarily classified into van der Waals forces and hydrogen bonds. Van der Waals forces include orientation forces between polar molecules, induction forces between polar and nonpolar molecules, and dispersion forces present in all molecular systems, with dispersion forces dominating nonpolar interactions. Hydrogen bonding is a unique type of intermolecular force characterized by distinct directionality and saturation; it forms when a hydrogen atom covalently bonded to a highly electronegative atom (such as nitrogen, oxygen, or fluorine) interacts with another electronegative atom. Although hydrogen bonding is fundamentally an electrostatic interaction, its strength is significantly greater than that of ordinary van der Waals forces. Due to its critical role in determining key material properties—including water’s high boiling point and the integrity of DNA’s double-helix structure—it is often considered separately.
Although van der Waals forces are inherently weak, they play a decisive role in the assembly and stabilization of supramolecular and polymeric structures, particularly in fully amorphous systems where dynamic interactions dominate material properties. Zhang et al.
［52］designed a quasi-solid-state polymer electrolyte by employing in-situ competitive cationic ring-opening copolymerization of 3-methyl-3-hydroxymethyl oxetane with 1,3-dioxolane to construct an integrated dynamic crosslinked network (IDCN). This strategy enables linear poly(dioxolane) chains to self-assemble into an ion-conductive framework, while hyperbranched multi-arm solid polymer plasticizers polymerize into uniformly distributed nodes, thereby preventing chain entanglement and forming a completely amorphous crosslinked network. The resulting quasi-solid-state polymer electrolyte exhibits a solid content exceeding 90%, combining high mechanical strength with stable electrode interfaces. Moreover, the dynamic nature of intermolecular interactions—primarily van der Waals forces between branched nodes and linear chains—allows the system to achieve rapid lithium-ion transport even at low temperatures. A solid-state lithium–sulfur battery based on this electrolyte demonstrated high reversible capacity and long cycle life at 25, 0, and −10 ℃, thereby validating how precise control of weak intermolecular forces can synergistically balance ion conductivity, mechanical strength, and interfacial stability within amorphous solid-state energy storage systems.
In addition to the study of van der Waals forces in intermolecular interactions, hydrogen bonds are also widely present in amorphous materials and play a crucial role in their structural stability, dynamic behavior, and functional performance. Unlike the highly ordered and periodically arranged hydrogen-bond networks found in crystalline materials, hydrogen bonds in amorphous systems typically exhibit dynamic, disordered characteristics with diverse topological structures. For example, in amorphous polymers, amorphous water, amorphous metal–organic frameworks, and the disordered regions of biomacromolecules, despite the absence of long-range periodicity, hydrogen bonds still form strong electrostatic interactions in the X—H···Y configuration (where X and Y represent O, N, F, or other electronegative atoms), locally connecting intermolecular or intramolecular segments and giving rise to short-range ordered domains. This disordered yet continuous hydrogen-bond network provides essential structural support for amorphous materials and influences their thermal stability, mechanical properties, and molecular fluidity. For instance, freeze-gel materials with a predominantly semicrystalline structure suffer from functional limitations due to uncontrollable ice-crystal formation during solidification, which severely restricts their application in flexible skin-like electronic devices. To address this challenge, Zhang et al.
［53］proposed a simple and effective strategy: the preparation of multifunctional freeze gels by constructing a fully amorphous polymer network. This approach employs antifreeze salts to precisely regulate the freezing point of the precursor solution, thereby effectively inhibiting ice-crystal growth and promoting the formation of exceptionally weak and uniformly distributed chain aggregates during the freezing process. Ultimately, this results in an amorphous polymer structure that is controllable and rich in free hydroxyl groups capable of forming hydrogen bonds (
Figure 4). Such multiscale microstructural design endows the freeze gel with a series of tissue-mimicking, ultra-sensitive properties, including a Young’s modulus below 10 kPa, excellent tensile extensibility, high transparency (approximately 92%), self-adhesion, and instantaneous self-healing capability (healing time < 0.3 s). Moreover, this material exhibits high ionic conductivity, outstanding cold resistance (withstanding temperatures as low as −58 °C), and good water-retention capacity, significantly advancing the development of skin-like freeze-gel electronics.
3.2 The Role and Influence of Amorphous Structure
In the microscopic world of materials science, the degree of atomic order has always been one of the core variables governing a material's macroscopic properties. While crystalline materials establish a stable performance framework through long-range periodic atomic packing, amorphous structures, with their unique configuration of "short-range order and long-range disorder," break the traditional correlation between structure and performance, becoming a breakthrough for innovative material functionalities
［54-55］. Unlike crystals, where atoms are stacked according to fixed lattice rules, atoms in amorphous structures maintain only limited coordination regularity within their nearest-neighbor regions, lacking any periodic repeating patterns over long distances. This structural disorder is precisely the origin of the special properties exhibited by amorphous materials. By altering the distribution of interatomic bonding energies, defect formation mechanisms, and energy transport pathways, amorphous structures enable materials to demonstrate performance advantages in mechanics, optics, and electronics that are difficult to achieve in crystalline counterparts. In this section, starting from the intrinsic characteristics of atomic arrangement in inorganic amorphous materials, we will systematically analyze how the fundamental nature of amorphous structure regulates key material properties, elucidate the underlying logic between structural disorder and property specificity, and ultimately reveal the core value of amorphous structures in advancing materials design innovation and expanding engineering applications.
The unique amorphous structure endows materials with exceptional mechanical properties. First, the long-range disordered atomic arrangement in amorphous nanomaterials eliminates crystalline defects, a feature that typically results in high strength. Second, amorphous nanomaterials exhibit good ductility, primarily due to their non-periodic and inhomogeneous internal structure, which enables them to withstand significant deformation under service conditions. Third, the disordered structure of amorphous nanomaterials induces delayed elasticity, manifesting as pronounced viscoelastic behavior. Moreover, certain amorphous nanomaterials also display special mechanical characteristics such as work hardening, tensile–compressive asymmetry, and self-healing ability. Addressing the issues of insufficient mechanical performance and weak interfacial bonding in traditional materials for enamel repair, our research group
［28］proposed a restorative strategy involving the in-situ growth of biocompatible amorphous ZrO
2ceramic layers via controlled hydrolysis of Zr
4+under oral-tolerable conditions. Defective enamel surfaces, after acid etching, were subjected to pH regulation using a tris(hydroxymethyl)aminomethane–hydrochloric acid buffer solution. Subsequently, at 10 ℃, an amorphous ZrO
2layer was grown in situ through the hydrolysis of ZrOCl
2·8H
2O. This restorative layer is free from grain boundaries and dislocation defects. The unsaturated Zr
4+forms strong chemical bonds with PO
4 3-in the enamel, while the penetration of Zr
4+into the interstices of hydroxyapatite (HA) nanowires generates physical interlocking, significantly enhancing the crystal–amorphous interfacial adhesion. The storage modulus of the amorphous ZrO
2enamel restoration (68.5 GPa) is comparable to that of healthy enamel (78.4 GPa), and its damping coefficient (0.06) even exceeds that of healthy enamel (0.05) (
Figure 5A–B). Building upon this foundation, we further focused on the multiscale design and fabrication of biomimetic enamel-like materials. By imitating the hierarchical structure of natural enamel, we constructed a high-performance artificial tooth enamel (ATE)
［37］. The outstanding mechanical properties of natural enamel stem from its multilevel architecture, where HA nanowires are interconnected by an amorphous interstitial phase (AIP) (
Figure 5C–E). We synthesized HA nanowires approximately 30 nm in diameter and coated their surfaces with about 3 nm of amorphous ZrO
2as AIP via in-situ hydrolysis of a Zr precursor. Finally, polyvinyl alcohol (PVA) was incorporated, and bidirectional freezing technology was employed to achieve parallel alignment and assembly of the nanowires. Following freeze-drying and compression treatment, a macroscopically processable artificial enamel was obtained. This material has an inorganic content of 78.06% yet exhibits superior comprehensive mechanical performance compared to natural enamel: Young’s modulus of 105.6 GPa, hardness of 5.9 GPa, flexural strength of 142.9 MPa, fracture toughness of 7.4 MPa·m
1/2, and a viscoelastic quality factor of 5.5 GPa—far exceeding those of conventional engineering materials (
Figure 5F). These enhanced performances are attributed to the robust chemical bonding between AIP, HA, and PVA (coordination of Zr
4+with PO
4 3-and —OH groups), constrained polymer chain motion, and the synergistic effects of the multiscale structure. Energy dissipation is achieved through crack deflection and nanowire pull-out mechanisms, thereby realizing a unified balance of high stiffness, hardness, toughness, and viscoelasticity.
In addition, to address the challenge that existing metal implants cannot simultaneously achieve osseointegration and energy dissipation, our research group
［21］proposed a biomimetic peri-implant ligament design strategy. This study mimics the hierarchical structure of the natural periodontal ligament by in situ growing an amorphous titanium dioxide nanotube array on the surface of a titanium implant. After a secondary anodization process to form a dense oxide layer that enhances interfacial bonding, chitosan was infiltrated and cross-linked to fabricate the peri-implant ligament (
Figure 5G–H). In this structure, the amorphous nanotube array serves as an amorphous interstitial phase, providing a bone-inductive nanotopography, while the chitosan simulates the lubricating and energy-dissipating functions of glycosaminoglycans. Performance tests revealed that the peri-implant ligament exhibits a Young’s modulus (27.6 GPa) and hardness (0.52 GPa) comparable to human bone, a loss factor (tan
δ≈0.053) five times that of pure titanium, and a viscoelastic quality factor ranging from 0.67 to 1.55 GPa—significantly exceeding those of conventional materials. In vivo experiments demonstrated an approximately 18% increase in the osseointegration contact ratio between the implant and bone, accompanied by a roughly 30% reduction in stress transfer from the implant to the surrounding bone, thereby achieving synergistic enhancement of both osseointegration and energy dissipation. The underlying mechanism is attributed to interfacial slippage between the amorphous nanotubes and the polymer, complex force transmission, and the activation of mechanosensitive/cytosolic signaling pathways such as FAK/MAPK and YAP nuclear translocation, which collectively promote robust osseointegration.
In the study of the electrical behavior of materials, the order and disorder of atomic arrangements have always played a crucial role. While crystalline materials provide well-defined transport pathways for charge carriers through long-range ordered periodic lattices, amorphous structures characterized by "short-range order and long-range disorder" offer unique possibilities for tuning electrical properties. Due to the difficulty in accurately characterizing the atomic structure of three-dimensional amorphous materials, Tian et al.
［56］leveraged the advantages of simplifying the system to two dimensions. Using boron–nitrogen heterocyclic aromatic hydrocarbons as precursors, they synthesized amorphous monolayer carbon (AMC) with varying degrees of disorder (DOD) on copper foil via chemical vapor deposition by controlling the growth temperature (275–800 ℃) (
Figure 6A). Atomic-scale characterization revealed that AMC consists of highly distorted nanocrystallites embedded within a continuous random network (CRN), and its degree of disorder can be described by two parameters: the presence or absence of medium-range order (MRO) and nanocrystallite density. Electrical measurements demonstrated that AMC-300 grown at 300 ℃ exhibits conductivity via variable-range hopping due to the presence of medium-range order, with a sheet resistance as low as 31.8 kΩ/□ (
Figure 6B). When the growth temperature was increased by 25 ℃, AMC-400 lost its medium-range order, resulting in a 10
9-fold drop in conductivity and becoming an insulator. In contrast, AMC-500 grown at even higher temperatures showed a recovery in conductivity due to the increased nanocrystallite density (
Figure 6C). Theoretical calculations established a correlation map between electrical conductivity, medium-range order, and the density of conducting sites, confirming the direct regulation of macroscopic electrical properties by the microstructure (
Figure 6D). This study is the first to establish a structure–property relationship for two-dimensional amorphous materials at the atomic level. The core advantage of amorphous states lies in the tunability of their degree of disorder, which enables broad and flexible control over electrical performance, offering a range of tunable electrical characteristics unattainable in crystalline materials. These findings provide unique insights into the development of novel two-dimensional amorphous electronic devices.
To address the challenge of insufficient performance in amorphous p-type semiconductors, which has hindered the development of complementary metal–oxide–semiconductor technology, Liu et al.
［57］proposed a design strategy for amorphous p-type semiconductors based on a tellurium–tellurium oxide mixed-phase system and achieved performance optimization through selenium alloying. They employed thermal evaporation using TeO
2and Se powders as precursors, followed by annealing at a low temperature of 225 ℃ to fabricate amorphous selenium-alloyed Te–TeO
x thin films. X-ray diffraction (XRD) and high-resolution TEM results confirmed that the structure is long-range disordered amorphous, containing Te–Te metallic bonds and a non-stoichiometric TeO
ₓphase (
Figure 6E). The p-channel thin-film transistors based on this material exhibited excellent performance: a hole mobility of approximately 15 cm
2/(V·s), an on/off current ratio of 10
6to 10
7, along with wafer-scale uniformity and long-term stability (
Figure 6F). This was primarily attributed to the short-range disorder of the amorphous structure, which allowed the 5p orbitals of Te to be fully delocalized within the network. Furthermore, the formation of Te–Se bonds through selenium alloying enhanced the continuity of the hole transport channels, resulting in a hole mobility significantly higher than that of conventional amorphous p-type semiconductors. In addition, the flexibility of the amorphous structure facilitated compositional tuning to optimize electrical performance, thereby suppressing excessively high hole concentrations while maintaining structural stability, which enabled the devices to exhibit good durability under bias stress and environmental aging conditions. By integrating these devices with n-type In
2O
3thin-film transistors, they successfully fabricated complementary circuits such as inverters, NAND gates, and NOR gates. These circuits demonstrated a voltage gain as high as 1300 at a supply voltage of 20 V, thereby validating their potential for use in low-cost, large-scale electronic devices (
Figure 6G–H).
In optical performance, crystalline silicon material, as the cornerstone of the microelectronics industry, has supported the development of the information age. However, due to its indirect optical transition characteristics, fixed bandgap width, and uncontrollable optical constants, it lacks superior optical performance. The essential difference between amorphous silicon and crystalline silicon lies in the non-periodic atomic arrangement of amorphous silicon, which endows it with unique optoelectronic properties that crystalline silicon does not possess, such as tunable bandgap width, controllable refractive index, and high light absorption coefficient. Because amorphous silicon is compatible with existing semiconductor processes and can be deposited over large areas at low temperatures, it has been widely applied in solar photovoltaics, infrared detection, and liquid crystal displays. By conducting in-depth research on the correlation mechanism between the microstructure and band structure of amorphous silicon and its optoelectronic properties, combined with metal doping strategies, it is expected to inject new vitality into silicon-based materials. Chen et al.
［58］doped germanium into an amorphous silica framework to prepare amorphous germanium–silicon oxide (GSO) that exhibits ultra-long afterglow and delayed fluorescence over a wide temperature range (
Figure 7A). Multiple luminescent centers enable this material to simultaneously possess unit stability and tunable emission from the ultraviolet to visible light regions (
Figure 7B). This germanium–silicon oxide can exhibit ultra-long afterglow even at room temperature; the underlying mechanism involves germanium defects sensitizing silicon luminescent centers through energy transfer. Furthermore, the amorphous structure of silica helps regulate the photoluminescence lifetime of the germanium–silicon oxide phosphor (
Figure 7C).
In response to the insufficient sensitivity of semiconductor-based surface-enhanced Raman scattering (SERS), Wang et al.
［59］proposed a strategy of employing amorphous zinc oxide nanocages to enhance performance. Using Cu
2O nanocubes as templates, they prepared both amorphous and crystalline zinc oxide nanocages by controlling the calcination temperature (
Figure 7D–E). SERS performance tests demonstrated that the amorphous ZnO nanocages exhibited an enhancement factor as high as 6.62×10
5for the 4-mercaptobenzoic acid probe molecule, significantly outperforming their crystalline counterparts (
Figure 7F). Mechanistic studies revealed that metastable electronic states weakened the binding of electrons at the amorphous surface. Density functional theory (DFT) simulations confirmed that the interfacial charge-transfer process was more efficient, leading to an amplification of the molecular polarizability tensor (
Figure 7G). XANES further verified the presence of π-bond components in the Zn—S bonds formed between the amorphous ZnO nanocages and the probe molecules, reflecting stronger semiconductor–molecule interactions (
Figure 7H). These π-bonds within the Zn—S linkages facilitated charge transfer between the molecules and the amorphous ZnO. The metastable state of the amorphous ZnO nanocages resulted in weaker surface electron confinement, promoting electron emission and transfer, thereby endowing them with higher charge-transfer capability compared to the crystalline form. Building upon the ZnO research, Wang et al.
［31］subsequently used graphene as a template and, by adjusting the calcination temperature, fabricated two-dimensional amorphous and crystalline TiO
2nanosheets. SERS performance tests showed that the amorphous TiO
2nanosheets achieved an enhancement factor of 1.86×10
6for the 4-mercaptobenzoic acid probe molecule, markedly superior to the crystalline TiO
2nanosheets (
Figure 7I). Mechanistic investigations indicated that the amorphous TiO
2nanosheets possessed a higher surface positive potential, which more effectively attracted the electron clouds of the molecules, thereby facilitating charge transfer from the molecules to the substrate. Due to the long-range disorder inherent in the amorphous phase, the surface Ti atoms experienced undercoordination and generated numerous oxygen vacancies, conferring a higher surface positive potential on the amorphous TiO
2nanosheets. DFT calculations revealed that the amorphous TiO
2exhibited a narrower band gap and a higher density of states, enhancing the substrate–molecule vibrational coupling and improving photogenerated charge-transfer efficiency, thus enabling the amorphous TiO
2nanosheets to demonstrate outstanding SERS activity. This work represents the first report of exceptional SERS activity in two-dimensional amorphous semiconductors, providing a new avenue for the development of subsequent high-sensitivity nonmetallic SERS technologies.
3.3 Multiscale Structure and Chemical Reactions of Amorphous Materials
The multiscale structure of amorphous materials (encompassing electronic structure, phase structure, and defect structure) can deeply regulate various chemical reaction processes through synergistic effects. From the perspective of electronic structure, the absence of long-range order results in a continuous state distribution that lowers the energy barrier for electron transitions. Meanwhile, localized electronic characteristics can optimize the efficiency of electron transfer with reactants, providing core support for charge transfer during the reaction process. At the phase structure level, although amorphous materials lack long-range periodicity, their short-range ordered atomic clusters serve as fundamental active units for reactions. The specific atomic coordination environment of these clusters determines the types of active sites, while the long-range disordered nature ensures their uniform distribution. Additionally, the long-range disorder of amorphous materials can reduce mass-transfer resistance, thereby facilitating the diffusion and transport of reactants and products. Regarding defect structure, the structural irregularity of amorphous materials gives rise to a large number of dangling bonds, vacancies, and coordinatively unsaturated atoms. These defects, acting as highly active sites, can strongly adsorb reactant molecules, modulate electron cloud density, and directly promote the breaking and restructuring of chemical bonds. More importantly, the quantity and type of defects can be controlled through preparation processes, enabling precise optimization of both reactivity and selectivity. The synergistic interplay among these three components collectively endows amorphous materials with unique reaction-regulating capabilities—surpassing certain crystalline materials—in applications such as catalysis and corrosion protection, where matching between structural and reactive properties is crucial.
Bismuth (Bi)-based main-group metal catalysts, owing to their weak binding affinity with hydrogen (H), have been extensively employed in electrocatalytic carbon–nitrogen reduction reactions. However, main-group metals typically exhibit only a single oxidation state, making it challenging to modulate their p-orbital electronic states. Our research group initially conducted free-energy calculations for urea synthesis and found that incorporating antimony (Sb) into BiOx can significantly reduce the free-energy barrier of the C–N coupling step—the rate-determining step in urea synthesis. Based on these findings, we precisely controlled the hydrolysis rate to grow amorphous SbxBi1−xOy clusters on the surface of oxidized graphene. In-situ X-ray absorption spectroscopy (XAS) results demonstrated that the introduction of Sb effectively stabilizes the spatial structure of the amorphous BiOx clusters, preventing their aggregation during the reaction process. More importantly, Sb can stabilize the electronic structure of the amorphous BiOx clusters, enabling Bi to maintain a highly active oxidation state throughout the reaction. Drawing upon both experimental and theoretical findings, we proposed a novel C–N coupling mechanism: molecular orbital symmetry plays a crucial role in achieving efficient C–N coupling, and the higher-valent active Bi species can effectively regulate molecular orbital symmetry to facilitate efficient C–N coupling. This work not only highlights the flexible structural composition and tunable electronic properties of amorphous materials but also demonstrates that introducing new components can alter the electronic states of main-group metals, thereby modifying the adsorption modes and reaction pathways of reactants and ultimately leading to more efficient catalytic routes.
The core of a catalytic reaction lies in the active sites, whose quantity and intrinsic activity directly determine the catalytic performance. In this regard, the amorphous phase significantly outperforms the crystalline phase
［60］. Therefore, achieving an amorphous phase transformation during the reaction can optimize the adsorption energy of reaction intermediates, thereby yielding dynamic, adaptive reaction sites that are better matched to the catalytic process. Liu et al.
［10］transformed the original crystalline covalent organic framework/carbon nanosheets (COF/NC) into an amorphous state through 20 minutes of potentiostatic activation (
Figure 8A). In-situ XRD measurements demonstrated that potentiostatic activation under an argon atmosphere does not induce any phase transition. However, when argon was replaced with nitrogen, the COF underwent a transformation from the crystalline phase to the amorphous phase, indicating that this transformation is associated with N
2(
Figure 8B). In-situ Raman spectroscopy revealed that, using N
2as the gas source, a distinct B—N stretching vibration peak gradually emerged at 800 cm
-1with increasing irradiation time, whereas no such transformation was observed when argon was used as the gas source (
Figure 8C). This phenomenon suggests that the lattice distortion of the COF is caused by the chemisorption of N
2or nitrogen-containing intermediates onto the catalytically active boron sites. Ultimately, the electrochemically activated COF achieved the highest ammonia synthesis activity among non-metallic catalysts at that time in the nitrogen reduction reaction (NRR). Kang et al.
［61］decomposed flower-like crystalline BiOBr particles into dispersed amorphous BiO
x cluster structures via in-situ electrochemical activation, thereby realizing efficient electrocatalytic nitrogen fixation. The N K-edge XANES results indicated the presence of Bi—N bonds on the catalyst surface after the NRR, confirming the formation of chemical bonds between the catalytically active species BiO
x and nitrogen-containing species (
Figure 8D). Furthermore, in an improved in-situ electrochemical cell, it was found that under reducing potentials, the oxidation state of Bi in the activated amorphous BiO
x clusters did not decrease but instead increased (
Figure 8E). This anomalous behavior is primarily attributed to the formation of Bi—N bonds during the catalytic reaction, which validates the strong responsiveness of the Bi system to N
2and its high catalytic activity in the NRR. Additionally, two-dimensional layered perovskite-like materials composed of edge-shared BO
2octahedra (ABO
2) do not possess electrocatalytic activity themselves. Liu et al.
［62］utilized Ag nanoparticles attached to amorphous cobalt-iron hydroxide nanosheets (Ag/CoFe-AN) as a metastable precursor for in-situ electrochemical self-reconstruction. During the electrochemical activation process, potential-driven dissolution–redispersion dynamics were initiated (
Figure 8f). The Ag nanoparticles oxidatively dissolved into Ag
+ions and embedded themselves within the interlayers of the cobalt-iron hydroxide, causing the original crystalline phases (such as the characteristic crystal structure of Ag) to disappear. Ultimately, a multi-element amorphous perovskite-like structure with uniform dispersion of Ag, Co, and Fe was formed, accompanied by crystal field distortion and atomic rearrangement, successfully modulating the local electronic states of the catalyst. This amorphous perovskite-like structure exhibited excellent oxygen evolution reaction performance, primarily due to the competitive interaction between hydrogen bonding and spatial occupancy by silver atoms, leading to elongation of specific axial bond lengths within the Co—O
6crystal field. The localized stress generated in the amorphous structure induced a high-spin state in Co
3+, thereby significantly enhancing the intrinsic activity of the cobalt active sites.
Defects in amorphous materials are the core regulatory units of their chemical reactivity. Their fundamental role lies in overcoming the structural limitations of crystalline materials by providing high-energy sites, dynamic mass-transfer channels, and heterogeneous electronic environments arising from structural disorder. Molybdenum disulfide (MoS
2) is typically difficult to use as an electrochemical NRR catalyst, primarily due to its strong hydrogen evolution reaction activity in aqueous media. Chu et al.
［63］ constructed an amorphous MoS
3 catalyst rich in sulfur vacancies, achieving excellent NRR performance (
Figure 9, A–B). The amorphous structure offers a larger electrochemical specific surface area, while the abundant sulfur vacancies serve as effective sites for capturing and adsorbing N
2 (
Figure 9, C–D). Compared with crystalline MoS
2, the amorphous MoS
3 with a high density of sulfur vacancies exhibits superior nitrogen chemisorption capability and faster electron transfer rates, thereby significantly enhancing NRR performance. More importantly, the sulfur vacancies in amorphous MoS
3, acting as catalytic centers, can effectively activate N
2 via a continuous-phase mechanism, reducing the energy barrier while efficiently suppressing the hydrogen evolution side reaction. Additionally, Xu et al.
［64］ addressed the issue of excessive hydrogen evolution in transition-metal-based catalysts by developing a Janus electrocatalyst incorporating antimony. In this catalyst, nickel is responsible for N
2 activation and H
2O dissociation, whereas antimony inhibits the two-electron hydrogen evolution process. Through an amorphization strategy, they introduced additional oxygen vacancies and low-coordinated dangling bonds (
Figure 9, E). This design mimics the “π-backbonding” mechanism to promote NRR, while the low-coordinated sites preferentially bind N
2, thereby reducing the occupation of active sites by hydrogen species. Oxygen vacancies can compensate for the adverse effects of carrier trapping, lower charge-transfer resistance, and accelerate electron transfer during nitrogen reduction (
Figure 9, F). DFT calculations indicate that increasing the number of oxygen vacancies enhances the electronic states of Ni and Sb near the Fermi level, strengthening orbital overlap with N
2 and thus facilitating N
2 adsorption and activation. For the amorphous sample, the energy barrier of the rate-determining step in nitrogen reduction (NH
2 → NH
3) is only 0.22 eV, which is lower than that of the crystalline counterpart; moreover, its NH
3 desorption energy barrier is also the lowest.
In addition to catalytic reactions, inorganic amorphous materials also exhibit numerous advantages in corrosion reactions. In the study of material corrosion behavior, the regularity and disorderliness of the microstructure are key factors determining the corrosion process. The absence of long-range periodicity in amorphous structures fundamentally alters the distribution of corrosion sites within the material, the mechanism of passive film formation, and the ion diffusion pathways. Addressing the issue of aluminum alloy bipolar plates in proton exchange membrane fuel cells being prone to corrosion in acidic environments, Ma et al.
［65］proposed a protective strategy involving rapid deposition of an amorphous carbon coating via candle combustion. By positioning the aluminum alloy 2 cm above a candle flame for only 4 minutes, an approximately 50 μm-thick amorphous carbon coating can be deposited. This coating is formed by the aggregation of nanocarbon particles and contains C—C/C
C, C—O functional groups, and exhibits superhydrophobic properties. The dense, continuous physical barrier formed by the aggregated amorphous nanocarbon particles significantly extends the diffusion path of corrosive media, effectively preventing their contact with the aluminum alloy substrate. Electrochemical tests demonstrate that in a 0.5 mol/L H
2SO
4 + 2 ppm (1 ppm = 1 × 10
-6) HF solution, the corrosion current density of Al—C decreases to 8.028 × 10
-8 A/cm
2, while the corrosion potential shifts positively by 0.86 V. In situ corrosion observation reveals no bubble formation on the coating surface, indicating its significant physical barrier effect. Immersion tests lasting 72 hours, high-temperature polarization tests, and potentiostatic tests all confirm its stable corrosion resistance performance. Furthermore, this coating possesses low interfacial contact resistance and a bond strength rating of Level 1, meeting the requirements for proton exchange membrane fuel cell applications. This strategy is simple, economical, and scalable, providing an efficient solution for corrosion protection of metal bipolar plates.
4 Conclusion and Future Work
From ancient times to the present, crystals have been recognized and appreciated for their regular shapes. Atoms in crystals exhibit a periodic and ordered arrangement, a characteristic that greatly simplifies experimental observation and theoretical deduction, ultimately leading to the establishment of relevant knowledge systems. It is worth noting that the discipline of crystallography is founded upon a mathematical and theoretical framework centered on the concepts of symmetry and long-range order, such as point groups, space groups, and Bloch’s theorem. However, among all matter constituting the universe, those possessing perfectly symmetric forms and periodic arrangements are exceedingly rare; most condensed-phase materials are actually based on a disordered and chaotic atomic configuration.
Unlike crystals, which possess periodic and regular atomic arrangements and have established systematic theoretical frameworks, amorphous materials present significant challenges in both experimental and theoretical studies due to their disordered structures. For example, despite breakthroughs in aberration-corrected microscopy and cryo-electron microscopy, the most fundamental structural issue—the atomic arrangement in amorphous materials—remains unresolved. At present, average structural information can only be obtained through pair distribution function analysis of diffraction patterns from amorphous samples (such as selected-area electron diffraction) or by fitting and simulating spectroscopic data (e.g., X-ray absorption fine structure spectra). Fortunately, recent advances in related techniques offer promising prospects: a coherent electron beam with a diameter of 3.6 Å can produce clear diffraction patterns via nanobeam electron diffraction, revealing the ordered local atomic environment. Moreover, atomic electron tomography enables the experimental determination of three-dimensional atomic positions in amorphous materials, demonstrating that short-range ordered units are interconnected to form crystal-like superclusters, thereby giving rise to medium-range order.
Over the past several decades, researchers have been dedicated to controlling the morphology of amorphous materials, tuning their compositions, and constructing diverse structures. Meanwhile, numerous high-performance amorphous materials have been reported. In some cases, the performance observed for specific applications is even comparable to that of state-of-the-art materials. By employing advanced in-situ characterization techniques and theoretical calculations, researchers have investigated the roles of defects, phase transformations, and interactions among different constituents within amorphous materials, thereby elucidating the structure–function relationships. However, the disordered atomic structure of amorphous materials poses significant challenges in establishing conclusive theories. Therefore, we propose three research directions for future reference by researchers.
(1) Research on the atomic arrangement and structural models of amorphous materials.
In traditional condensed matter crystallography research, systematic analysis of standard ordered crystal models enables precise investigation of the physical and chemical properties of crystals with different structures or compositions. Furthermore, by introducing various defects into these models, clear structure–property relationships can be established, providing theoretical guidance for experimental synthesis and thereby enabling targeted control of material properties. However, the study of amorphous materials faces fundamentally different challenges: existing characterization techniques typically yield only average atomic information, making it difficult to obtain atomic-resolution structural details, let alone fully reveal the complex interactions arising from strong coupling among atoms or structural units. Consequently, overcoming the technical bottlenecks in atomic arrangement analysis and structural modeling of amorphous materials has become crucial for advancing this field. Currently, understanding of the relationship between structural units and properties in amorphous materials is steadily deepening. Meanwhile, innovations in fundamental physics theories and rapid advancements in characterization technologies are fundamentally alleviating the difficulties associated with amorphous structure analysis—for example, the development of advanced characterization methods such as multi-slice local orbital tomography, as well as the establishment of structural models like double percolation. These cutting-edge advances are progressively resolving the research challenges posed by long-range disorder, thereby providing a solid theoretical and experimental foundation for the targeted design and performance optimization of amorphous materials.
(2) Controlled preparation of amorphous materials.
Amorphous materials exhibit short-range order arising from specific chemical bonds within the local coordination environment, which is confined to the atomic scale. Achieving ordered arrangements at the nanoscale remains a significant challenge. Currently, there are very few reports on the controllable preparation of amorphous materials, let alone precise control over their morphology and composition. To overcome this bottleneck, we have proposed several general strategies to achieve template-assisted, controllable synthesis of a series of ultrathin one-dimensional, ultra-thin two-dimensional, and hollow three-dimensional amorphous nanomaterials. Nevertheless, the preparation of many amorphous nanomaterials still poses considerable challenges, such as that of amorphous noble-metal nanowires. In particular, the large-scale, controllable fabrication of amorphous nanomaterials is still in the exploratory stage, severely hindering both fundamental research and practical applications of these materials. Therefore, the development of a universal method for the large-scale preparation of amorphous nanomaterials holds considerable significance.
(3) Stability of amorphous materials during service.
With the development of in-situ techniques and advanced methods, the real structural changes of materials during service have received increasing attention. The in-situ self-reconstruction that may occur under operating conditions has made the true state of materials increasingly elusive. A typical example is the behavior of catalysts in actual catalytic environments, where many studies regard the amorphous phase after catalytic transformation as the true active phase of the catalyst. More complexly, amorphous materials exist in a highly mutable state; their relaxation toward crystallinity also presents an unavoidable obstacle to accurately understanding their intrinsic properties during complex service processes: most amorphous catalysts cannot withstand high-temperature environments, and under illumination, their amorphous structures may transform into crystalline forms. Furthermore, during mechanical testing, amorphous materials often undergo intricate and disordered structural transformations. All these factors serve as significant barriers to research on the structure–function–performance relationships of amorphous materials. To address this issue, the development of more precise and reliable in-situ equipment would be highly beneficial.
In 1995, P.W. Anderson asserted: “Perhaps the most profound and intriguing unsolved mystery in solid-state theory is the theoretical understanding of the glassy state and the glass transition, which may lead to breakthrough advances in the next decade.” Since then, the academic community has increasingly delved into the unique structural characteristics of amorphous materials, continually uncovering novel properties of amorphous nanomaterials. With the continuous advancement of characterization techniques and theoretical frameworks for amorphous materials, the pivotal role of these disordered systems in condensed matter physics will undoubtedly become ever more prominent.
the National Natural Science Foundation of China(52422210)
the Postdoctoral Fellowship Program of CPSF(GZC20242149)
the China Postdoctoral Science Foundation(2025T181115)
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