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Colloidal amorphous structures comprise short-range ordered arrays of monodisperse submicrometer-sized particles. They exhibit angle-independent structural color and hence are expected to be promising candidates for advanced color materials. In particular, non-close-packed colloidal amorphous structures embedded in soft polymers can alter the angle-independent color through stimuli-induced volume changes in the polymer. Consequently, such materials should have significant potential for application in sensor devices. This paper reports the preparation of an elastomer-immobilized non-close-packed colloidal amorphous film with an angle-independent color using a hydrogel-immobilized non-close-packed colloidal amorphous film as the starting material. The swelling solvent (i.e., water) in the hydrogel film was replaced with a hydrophilic elastomer precursor solution, which was photopolymerized to immobilize the colloidal amorphous structure with the separated particles within the elastomer film. The color of the elastomer-immobilized non-close-packed colloidal amorphous film was angle-independent and was easily altered under stretching. Furthermore, hydrophilic carbon black dispersed well in the hydrophilic elastomer precursor solution, improving the saturation of the resultant elastomer-immobilized non-close-packed colloidal amorphous film. The flexible nature of the prepared film should allow it to be attached to curved surfaces, thereby promoting its application as a simple strain sensor to express invisible strains through color changes.

Crystalline, amorphous, and crystalline–amorphous materials have become three important electrode materials for the bottleneck oxygen‐evolving reaction (OER) in the promising hydrogen‐producing technology of water splitting. With the rapid development of in situ/ex situ characterizations, the understanding of active sites in electrocatalysts has been deepened via the structure–activity/stability relationships extracted from the observations on catalysts during/after the OER. Herein, the origins of changes in initial crystalline, amorphous, and crystalline–amorphous materials during/after the OER are systematically analyzed and the underlying variation effects on catalyst activity and stability are discussed based on recent representative studies, aiming at guiding OER catalyst design in the future. Crystalline, amorphous, and crystalline–amorphous materials have been explored for catalyzing the oxygen‐evolving reaction (OER). However, a systematic insight into the origins and effects of the behaviors on initial crystalline, amorphous, and crystalline–amorphous materials during/after the OER is still absent. Herein, it is attempted to offer a systematic viewpoint on these issues to guide the rational design of electrocatalysts.

Mg-based alloys are regarded as highly promising materials for hydrogen storage. Despite significant improvements of the properties for Mg-based alloys, challenges such as slow hydrogen absorption/desorption kinetics and high thermodynamic stability continue to limit their practical application. In this study, to assess hydrogen storage alloys with enhanced properties, incorporating both internal microstructure modulation through the preparation of amorphous/nanocrystalline structures and surface property enhancement with the addition of Cu and carbon nanotubes (CNTs), the kinetic properties of activation and hydrogenation, thermodynamic properties, and dehydrogenation kinetics are tested. The results reveal a complementary interaction between the added Cu and CNTs, contributing to the superior hydrogen storage performance observed in sample 7A-2Cu-1CNTs with an amorphous/nanocrystalline structure compared to the other experimental samples. Additionally, the samples are fully activated after the initial hydrogen absorption and desorption cycle, demonstrating outstanding hydrogenation kinetics under both high and low temperature experimental conditions. Particularly noteworthy is that the hydrogen absorption exceeds 1.8 wt.% within one hour at 333 K. Furthermore, the activation energy for dehydrogenation is decreased to 64.71 kJ·mol −1 . This research may offer novel insights for the design of new-type Mg-based hydrogen storage alloys, which possess milder conditions for hydrogen absorption and desorption.

The physical properties of polymers are significantly affected by relaxation processes. Recently, we reported that poly(diethyl fumarate) (PDEF) shows two thermal anomalies on DSC measurement, despite the fact that it is a homopolymer. We attribute these two relaxations α relaxation and β relaxation, respectively. In this study, we investigate the two relaxations of fumarate-containing polymers by DSC, solid-state NMR, and X-ray scattering. The two relaxations are present even in a copolymer of diethyl fumarate and ethyl acrylate with fumarate segments of 30%. We used poly(methyl methacrylate) (PMMA) as a model polymer for comparison, since there are detailed investigations of its dynamics and physical properties. Solid-state NMR indicates that the very local relaxation of poly(fumarate)s is not significantly different from that of PMMA. The tensile test showed that PDEF is still brittle at above β relaxation temperature and below α relaxation temperature. It was revealed that a structural anisotropy appeared when PDEF was extended at around α relaxation temperature. We discuss the effect of the glassy packing of the rigid polymer chain including the DEF segments on the strong β relaxation behavior. Our data provide insight into the microscopic mechanism of β relaxation of vinyl polymers.

Gel-immobilized colloidal amorphous structures comprise short-range-ordered monodisperse submicrometer particles embedded into a soft polymer gel. They exhibit an angle-independent structural color that is tunable in response to external stimuli via a volume change in the gel, which has significant potential for the development of sensors that respond to stimuli via angle-independent color changes. In this study, the amorphous structure of a charged colloidal suspension in water was immobilized in a thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) gel film and simultaneously attached to a polyethylene terephthalate (PET) substrate. The gel film exhibited a uniform angle-independent color that changed in response to changes in temperature (i.e., thermosensitivity). Attachment to the PET substrate suppressed changes in the gel film area and film distortion, despite significant volume changes in the gel. Consequently, the degree of thermosensitivity was enhanced. The PET-attached gel-immobilized colloidal amorphous film was easy to handle and had excellent flexibility, allowing it to wrap around the surfaces of curved objects. These features are advantageous for sensor applications.

Compared with polyolefins that are used as single-use plastics, polylactic acid (PLA) has a lower tear strength in films. The relationship between the tear strength and the higher-order structure of films was investigated using PLA films that absorbed moisture at 30 °C and 95% relative humidity (RH) or that had been annealed under reduced pressure conditions. Although the mobile amorphous (MAm) amount did not change under high humidity, the film became brittle due to enthalpy relaxation. The crystallization by annealing also caused embrittlement, and the MAm amount decreased to 10%. The displacement until tearing is lowered from 2.5 to 0.5 mm in both cases. However, in situ retardation measurements revealed that there was a significant difference in the fracture morphology of the torn tip. When crystallized, the molecular chains and crystals are oriented in the tensile direction of the film, and a fragmented structure is observed in the ligament. Embrittlement due to enthalpy relaxation caused a weak orientation perpendicular to the tensile direction of the film, and cracks occurs along with this orientation.

Amorphous materials have no long-range order, but there are ordered structures at short range (2–5 Å), medium range (5–20 Å) and even longer length scales 1 – 5 . While regular 6 , 7 and semiregular polyhedra 8 – 10 are often found as short-range ordering in amorphous materials, the nature of medium-range order has remained elusive 11 – 14 . Consequently, it is difficult to determine whether there exists any structural link at medium range or longer length scales between the amorphous material and its crystalline counterparts. Moreover, an amorphous material often crystallizes into a phase of different composition 15 , with very different underlying structural building blocks, further compounding the issue. Here, we capture an intermediate crystalline cubic phase in a Pd-Ni-P amorphous alloy and reveal the structure of the medium-range order, a six-membered tricapped trigonal prism cluster (6M-TTP) with a length scale of 12.5 Å. We find that the 6M-TTP can pack periodically to several tens of nanometres to form the cube phase. Our experimental observations provide evidence of a structural link between the amorphous and crystalline phases in a Pd-Ni-P alloy at the medium-range length scale and suggest that it is the connectivity of the 6M-TTP clusters that distinguishes the crystalline and amorphous phases. These findings will shed light on the structure of amorphous materials at extended length scales beyond that of short-range order. An intermediate cube phase with a medium-range order structure is identified in Pd-Ni-P metallic glass, which links the amorphous and crystalline phases.

Amorphous solids such as glass, plastics and amorphous thin films are ubiquitous in our daily life and have broad applications ranging from telecommunications to electronics and solar cells 1 – 4 . However, owing to the lack of long-range order, the three-dimensional (3D) atomic structure of amorphous solids has so far eluded direct experimental determination 5 – 15 . Here we develop an atomic electron tomography reconstruction method to experimentally determine the 3D atomic positions of an amorphous solid. Using a multi-component glass-forming alloy as proof of principle, we quantitatively characterize the short- and medium-range order of the 3D atomic arrangement. We observe that, although the 3D atomic packing of the short-range order is geometrically disordered, some short-range-order structures connect with each other to form crystal-like superclusters and give rise to medium-range order. We identify four types of crystal-like medium-range order—face-centred cubic, hexagonal close-packed, body-centred cubic and simple cubic—coexisting in the amorphous sample, showing translational but not orientational order. These observations provide direct experimental evidence to support the general framework of the efficient cluster packing model for metallic glasses 10 , 12 – 14 , 16 . We expect that this work will pave the way for the determination of the 3D structure of a wide range of amorphous solids, which could transform our fundamental understanding of non-crystalline materials and related phenomena. A method that achieves atomic-resolution tomographic imaging of an amorphous solid enables detailed quantitative characterization of the short- and medium-range order of the three-dimensional atomic arrangement.

Solids in nature can be generally classified into crystalline and non-crystalline states 1 – 7 , depending on whether long-range lattice periodicity is present in the material. The differentiation of the two states, however, could face fundamental challenges if the degree of long-range order in crystals is significantly reduced. Here we report a paracrystalline state of diamond that is distinct from either crystalline or amorphous diamond 8 – 10 . The paracrystalline diamond reported in this work, consisting of sub-nanometre-sized paracrystallites that possess a well-defined crystalline medium-range order up to a few atomic shells 4 , 5 , 11 – 13 , was synthesized in high-pressure high-temperature conditions (for example, 30 GPa and 1,600 K) employing face-centred cubic C 60 as a precursor. The structural characteristics of the paracrystalline diamond were identified through a combination of X-ray diffraction, high-resolution transmission microscopy and advanced molecular dynamics simulation. The formation of paracrystalline diamond is a result of densely distributed nucleation sites developed in compressed C 60 as well as pronounced second-nearest-neighbour short-range order in amorphous diamond due to strong sp 3 bonding. The discovery of paracrystalline diamond adds an unusual diamond form to the enriched carbon family 14 – 16 , which exhibits distinguishing physical properties and can be furthered exploited to develop new materials. Furthermore, this work reveals the missing link in the length scale between amorphous and crystalline states across the structural landscape, having profound implications for recognizing complex structures arising from amorphous materials. A study describes the synthesis, structural characterization and formation mechanism of a paracrystalline state of diamond, adding an unusual form of diamond to the family of carbon-based materials.

Amorphous alloys, also known as metallic glasses, are solid metallic materials having long-range disordered atomic structures. Compared to crystalline alloys, amorphous alloys not only have metallic characters, but also possess several distinct properties associated to the amorphous structure, such as isotropy, composition flexibility, unsaturated surface, etc. As a result, amorphous alloys offer a class of highly promising materials for catalyzing electrochemical reactions. In this minireview, the preparation, characterization and electrocatalytic performances of a variety of metallic amorphous alloy materials are summarized. The influences of the amorphous alloy structure on different electrochemical reactions are discussed. Finally, a summary on the advantages and challenges of amorphous alloys in electrocatalysis is provided, along with some perspectives about the future research directions.