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Nonexponential relaxations are universal characteristics for glassy materials. There is a well-known hypothesis that nonexponential relaxation peaks are composed of a series of exponential events, which have not been verified. In this Letter, we discover the exponential relaxation events during the recovery process using a high-precision nanocalorimetry, which are universal for metallic glasses and organic glasses. The relaxation peaks can be well fitted by the exponential Debye function with a single activation energy. The activation energy covers a broad range from α relaxation to β relaxation and even the fast γ/β′ relaxation. We obtain the complete spectrum of the exponential relaxation peaks over a wide temperature range from 0.63 T g to 1.03 T g , which provides solid evidence that nonexponential relaxation peaks can be decomposed into exponential relaxation units. Furthermore, the contribution of different relaxation modes in the nonequilibrium enthalpy space is measured. These results open a door for developing the thermodynamics of nonequilibrium physics and for precisely modulating the properties of glasses by controlling the relaxation modes.

Microwave is of promising applications in various chemical and material processes, however, the interactions between the microwave and the molecules from atomistic scales are lack of understanding. ReaxFF reactive molecular dynamics simulations were carried out to get insights into the interactions between the microwave and polyacrylonitrile (PAN) during microwave heating. It was found that the temperature evolution of the system was dependent on the electric field strength and frequency of the microwave. The alternate change of the electric field of the microwave leads to the alternate fluctuation of the temperature. We surprisingly predicted the atomistic hot‐spot effect of microwave heating of PAN that the cyano groups were selectively heated. With an electric field intensity of 0.6 V Å‐1 and a frequency of 60 GHz, the temperature of the hot‐spot atoms was 300 and 500 K higher than the carbon and hydrogen atoms in the PAN backbone, respectively. We also analyzed the thermal runaway behavior of the system during microwave irradiations and found that it was attributed to the decomposition of PAN into smaller polar molecules. This work suggests that it is possible to selectively and effectively activate the cyano groups of PAN to improve their reactivity.

Stress relief can improve the soft magnetic properties of Fe-based metallic glasses (MGs) and is vital for industrial applications. In this work, we investigated the evolution of soft magnetic properties, relaxation dynamics, and mechanical properties of Fe-based MGs under different applied tensile strains and stress relaxation times. We found that stress relaxation can significantly reduce coercivity Hc by 95% compared with as-quenched state. Furthermore, the coercivity Hc, apparent activation volume Vact and time constant tr all show analogous two-stage variation with annealing time, accompanied by approximate crossovers. This suggests that the microstructure change emerges, further verified by the domain wall motion and the transition from elastic to plastic. These results are helpful in preparing Fe-based MGs with excellent soft magnetic and mechanical properties by controlling the stress relaxation condition.

In this letter, we report clear correlations between the glass transition temperature Tg, the crystallization temperature Tx, the Curie temperature TC and the electronegativity based on statistically analyzing more than 200 kinds of soft magnetic Fe-based amorphous alloys. The underlying physical origin of these correlations is discussed. Based on these correlations, the influences of various alloying elements are classified. These results are helpful for designing new soft magnetic amorphous alloys with high thermal stability.

Helium-3 (3He) is a noble gas that has critical applications in scientific research and promising application potential as clean fusion energy. It is thought that the lunar regolith contains large amounts of helium, but it is challenging to extract because most helium atoms are reserved in defects of crystals or as solid solutions. Here, we find large amounts of helium bubbles in the glassy surface layer of ilmenite particles that were brought back by the Chang’E-5 mission. The special disordered atomic packing structure of glasses should be the critical factor for capturing the noble helium gas. The reserves in bubbles do not require heating to high temperatures to be extracted. Mechanical methods at ambient temperatures can easily break the bubbles. Our results provide insights into the mechanism of helium gathering on the moon and offer guidance on future in situ extraction.

Owing to the nonequilibrium nature, the energy state of metallic glasses (MGs) can vary a lot and has a critical influence on the physical properties. Exploring new methods to modulate the energy state of glasses and studying its relationship with properties have attracted great interests. Herein, we systematically investigate the energy state, mixing entropy and physical properties of Zr–Ti–Cu–Ni–Be multicomponent high entropy MGs by experiments and simulations. We find that the energy state increases along with the increase of mixing entropy. The yield strength and thermal stability of MGs are also enhanced by high mixing entropy. These results may open a new door on regulation of energy states and thus physical properties of MGs.

The relaxation kinetics and phase transformations of the confined D-mannitol (DM) in nanoporous alumina are studied in-situ using a high-precision nano-calorimeter. We find that the crystallization behavior can be suppressed when it is confined in nanopores smaller than 50 nm. The confined DM glass has a much smaller fragility (~76) than free DM glass (~125), confirming the enhanced glass-forming ability. It is intriguing that during isothermal annealing both the confined and free DM glasses relaxation kinetics experience two relaxation stages that have distinct activation energies. The relaxation activation energy of the confined glass is about 25%-29% smaller than the free glass, which is attributed to the reduced dimensionality. The abnormal kinetics observed in the confined DM glass open a new avenue for preparing stable glasses.

Dopamine (DA) has been applied in surface chemistry because of its green and simple polymerization process. However, the polymerization kinetics is slow for mass production. Herein, we proposed a novel method to increase the polymerization rate of DA significantly. The DA solution was treated by a two-step method using microwave irradiation and oxygen oxidation. As a result, the DA solution turned dark only in 6 min. The UV–vis spectra and molecular dynamics showed that microwave irradiation promotes the generation of reactive oxygen species, and the oxygen is used as a supplement to compensate for the overflow of oxygen during the microwave heating process. This study provides a new promising choice to polymerize DA quickly and will inspire related applications in various fields.

Isothermal annealing is a very useful strategy in modulating the properties and structures of metallic glasses, which has been regarded as a single relaxation progress. In this work, the enthalpy relaxation of Au-based metallic glasses are studied using a high-precision calorimetry. An intriguing transition from β relaxation to α relaxation was confirmed during isothermal annealing. Energy landscape model is proposed to quantitatively explain how the relaxation modes transform. It is found that a small enthalpy decrease (about 0.8 kJ/mol) in initial state causes an extremely large increase (about 100 kJ/mol) in relaxation barrier, which is attributed to the enhanced cooperative atomic motion. These results open a gate for precisely understanding the role of different relaxation modes in modifying the properties of metallic glasses.

Developing advanced catalysts for water splitting is the kernel in hydrogen clean-energy technologies. In this paper, an Al82Ni6Co3Mn3Y3Au3 nanocrystalline ribbon is dealloyed as the catalyst in hydrogen evolution reaction (HER), which exhibits outstanding catalytic activity in acidic solution. Its overpotential is about 24 mV @ 10 mA cm−2 and the Tafel slope is about 43 mV dec−1, which are comparable to commercial noble Pt/C electrodes (30 mV @ 10 mA cm−2 and 28 mV dec−1). Such a superior catalytic performance is attributed to the large specific surface area and low charger transferring resistivity of the dealloyed nanocrystalline electrode. The hybrid nanoporous structures composed of nanoporosity and nanoparticles of Au-Ni-Co-Mn-Y alloys and the synergic effects among the multiple components are desirable in catalysts. These results suggest that nanocrystalline multicomponent alloys are promising precursors for fabricating advanced HER catalysts.

It has been a long-standing puzzling problem that some glasses exhibit higher glass transition temperatures (denoting high stability) but lower activation energy for relaxations (denoting low stability). In this paper, the relaxation kinetics of the nanoconfined D-mannitol (DM) glass was studied systematically using a high-precision and high-rate nanocalorimeter. The nanoconfined DM exhibits enhanced thermal stability compared to the free DM. For example, the critical cooling rate for glass formation decreases from 200 K/s to below 1 K/s; the T g increases by about 20 K–50 K. The relaxation kinetics is analyzed based on the absolute reaction rate theory. It is found that, even though the activation energy E* decreases, the activation entropy S* decreases much more for the nanoconfined glass that yields a large activation free energy G* and higher thermal stability. These results suggest that the activation entropy may provide new insights in understanding the abnormal kinetics of nanoconfined glassy systems.

Crystallization kinetics of phase change materials (PCMs) at high temperatures is of key importance for the extreme speed of data writing and erasing. In this work, the crystallization behavior of one of the typical PCMs, GeTe, has been studied using ultrafast differential scanning calorimetry (DSC) at high heating rates up to 4 × 104 K s–1. A strong non-Arrhenius temperature-dependent viscosity has been observed. We considered two viscosity models for estimating the crystal growth kinetics coefficient (Ukin). The results showed that the MYEGA model was more suitable to describe the temperature-dependent viscosity and the crystal growth kinetics for supercooled liquid GeTe. The glass transition temperature (Tg) and fragility m were estimated to be 432.1 K and 130.7, respectively. The temperature-dependent crystal growth rates, which were extrapolated by the MYEGA model, were in line with the experimental results that were measured by in situ transmission electron microscopy at a given temperature. The cry...

In an era of sustainable development and innovation ecosystem, a high-energy density is one of the important requirements for the development of new energy storage modalities, including battery technology. In a metal-air battery (MAB) system, metals function as negative active substances, and oxygen in the air acts as the positive component. Research to date confirms that, MABs have an exceptionally high energy density, durability, and specific power compared to conventional batteries. In addition, they are environmentally friendly, low-cost, and lightweight. In battery construction, fibrous materials have been shown to improve thermal stability, electronic & ionic conductivity, and cyclical performance of MABs. This is due to their outstanding properties that include large surface area-to-volume ratio, controllable morphology and highly porous structure. In this review, the basic working principle of MABs is presented. A critical overview that using a diverse array of fibrous materials related to metal-based, metal oxide-based, and carbon-based fiber shape materials used in MABs such as Li–O2, Zn–O2, Mg–O2, and Al–O2 systems are comprehensively summarized. We also identify the most promising systems according to their established scientific database with respect to sustainable development. Finally, the existing challenges and prospects are stressed considering the future perspective of MABs and fiber-shaped structure electrode material.

The extraordinary magnetocaloric effect of Fe 80 P 13 C 7 bulk glassy rods has been studied. The magnetic entropy change (Δ S M ) and refrigerant capacity ( RC ) values under 1.5 T can reach 2.20 J kg −1 K −1 and 125 J kg −1 , respectively, which are the largest values among present ternary Fe-based glassy alloys. It is found that the magnetocaloric effect vs temperature curve gradually changes into two peaks with increasing magnetic fields, leading to a much wider Δ S M peak and thus a larger RC . This extraordinary magnetocaloric effect in Fe 80 P 13 C 7 may be attributed to the coexistence of magnetic transition and spin reorientation transition.

The work uses the data in the TTS mode of BATSE to analyze the time lags and pulse widths of GRB960113 and GRB960722 in high as well as low energy bands. The results show that their time lags increase monotonously. This phenomenon can reasonably be interpreted with the model of internal shock waves of γ-ray bursts (GRB). Perhaps we obtain the direct observational evidence for the fireball model of GRBs for the first time.