Understanding glassy phenomena in materials

Shear banding, aging and noise dynamics in soft glassy materials

The `soft glassy rheology' (SGR) model gives an appealing account of the flow of nonergodic soft materials in terms of the local yield dynamics of mesoscopic elements. Newtonian, power-law, and yield-stress fluid regimes arise on varying a `noise temperature', x. Here we extend the model, to capture the idea that the noise is largely caused by yield itself. The extended model can account for the viscosity-bifurcation and shear-banding effects reported recently in a wide range of soft materials. A variant model may shed light on shear banding and strain-rate hysteresis seen in glassy star polym…

Anisotropic Structural Predictor in Glassy Materials

There is a growing evidence that relaxation in glassy materials, both spontaneous and externally driven, is mediated by localized soft spots. Recent progress made it possible to identify the soft spots inside glassy structures and to quantify their degree of softness. These softness measures, however, are typically scalars, not taking into account the tensorial/anisotropic nature of soft spots, which implies orientation-dependent coupling to external deformation. Here we derive from first principles the linear response coupling between the local heat capacity of glasses, previously shown to pr…

Prediction of long and short time rheological behavior in soft glassy materials

We present an effective time approach to predict long and short time rheological behavior of soft glassy materials from experiments carried out over practical time scales. Effective time approach takes advantage of relaxation time dependence on aging time that allows time-aging time superposition even when aging occurs over the experimental timescales. Interestingly experiments on variety of soft materials demonstrate that the effective time approach successfully predicts superposition for diverse aging regimes ranging from sub-aging to hyper-aging behaviors. This approach can also be used to …

Linear Response Theory for Hard and Soft Glassy Materials

Despite qualitative differences in their underlying physics, both hard and soft glassy materials exhibit almost identical linear rheological behaviors. We show that these nearly universal properties emerge naturally in a shear-transformation-zone (STZ) theory of amorphous plasticity, extended to include a broad distribution of internal thermal-activation barriers. The principal features of this barrier distribution are predicted by nonequilibrium, effective-temperature thermodynamics. Our theoretical loss modulus $G"(ω)$ has a peak at the $α$ relaxation rate, and a power law decay of the form …

具有可调拉伸性的软玻璃态材料

Soft glassy materials with tunable extensibility

本文提出一种软玻璃态微凝胶与高分子量线性聚合物混合的模型材料，建立了剪切与拉伸流变设计准则，实现了在几乎不改变剪切屈服应力和弹性模量的情况下大幅调控拉伸性。

Time Temperature Superposition in Soft Glassy Materials

Soft glassy materials are out of thermodynamic equilibrium and show time dependent slowing down of the relaxation dynamics. Under such situation these materials follow Boltzmann superposition principle only in the effective time domain, wherein time dependent relaxation processes are scaled by a constant relaxation time. In this work we extend effective time framework to successfully demonstrate time - temperature superposition of creep and stress relaxation data of a model soft glassy system comprised of clay suspension. Such superposition is possible when average relaxation time of the mater…

Progress, challenges and perspectives of computational studies on glassy superionic conductors for solid-state batteries

Sulfide-based glasses and glass-ceramics showing high ionic conductivities and excellent mechanical properties are considered as promising solid-state electrolytes. Nowadays, the computational material techniques with the advantage of low research cost are being widely utilized for understanding, effectively screening and discovering of battery materials. In consideration of the rising importance and contributions of computational studying on the glassy SSE materials, here, this work summarizes the common computational methods utilized for studying the amorphous inorganic materials, review the…

High-performance super-capacity using activated glassy carbon foam

An urgent demand for new sustainable and efficient energy conversion and storage devices required the development of novel electrode materials with increased specific capacitance. However, low mass loading, poor scalability, and low working voltage always limited further practical application of most reported high-performance supercapacitors electrode materials. In this work, we demonstrated the preparation of activated glassy carbon foam as high-performance electrode via oxidizing commercial glassy carbon foam in HNO3 solution.

Rheological hysteresis in soft glassy materials

The nonlinear rheology of a soft glassy material is captured by its constitutive relation, shear stress vs shear rate, which is most generally obtained by sweeping up or down the shear rate over a finite temporal window. For a huge amount of complex fluids, the up and down sweeps do not superimpose and define a rheological hysteresis loop. By means of extensive rheometry coupled to time-resolved velocimetry, we unravel the local scenario involved in rheological hysteresis for various types of well-studied soft materials. We introduce two observables that quantify the hysteresis in macroscopic …

无序诱导的软玻璃材料中的应力-流动错位：多向剪切揭示

Disorder-induced stress-flow misalignment in soft glassy materials revealed using multi-directional shear

本研究通过多轴剪切实验和弹塑性模型，揭示软玻璃材料中剪切历史导致应力-流动错位及各向异性屈服面，源于局部力学无序，为探测局部屈服应力提供新方法。

Steady-state, effective-temperature dynamics in a glassy material

We present an STZ-based analysis of numerical simulations by Haxton and Liu (HL). The extensive HL data sharply test the basic assumptions of the STZ theory, especially the central role played by the effective disorder temperature as a dynamical state variable. We find that the theory survives these tests, and that the HL data provide important and interesting constraints on some of its specific ingredients. Our most surprising conclusion is that, when driven at various constant shear rates in the low-temperature glassy state, the HL system exhibits a classic glass transition, including super-…

Rheology of Hard Glassy Materials

Glassy solids may undergo a fluidization (yielding) transition upon deformation whereby the material starts to flow plastically. It has been a matter of debate whether this process is controlled by a specific time scale, from among different competing relaxation/kinetic processes. Here, two constitutive models of cage relaxation are examined within the microscopic model of nonaffine elasto-plasticity. One (widely used) constitutive model implies that the overall relaxation rate is dominated by the fastest between the structural ($α$) relaxation rate and the shear-induced relaxation rate. A dif…

Accelerating Simulated Annealing of Glassy Materials with Data Assimilation

The ultra-long relaxation time of glass transition makes it difficult to construct atomic models of amorphous materials by conventional methods. We propose a novel method for building such atomic models using data assimilation method by simulated annealing with an accurately computed interatomic potential augmented by penalty from experimental data. The advantage of this method is that not only can it reproduce experimental data as the structure refinement methods like reverse Monte Carlo but also obtain the reasonable structure in terms of interatomic potential energy. In addition, thanks to …

Dynamic Model of Super-Arrhenius Relaxation Rates in Glassy Materials

We propose that the super-Arrhenius relaxation rates observed in glassy materials are determined by thermally nucleated rearrangements of increasing numbers of molecules at decreasing temperatures. In our model of this mechanism, string-like fluctuations in the neighborhood of shear transformation zones (STZ's) provide routes along which rearrangements can propagate, and the entropy associated with long enough strings allows the rearrangement energy to be distributed stably in the surrounding material. We further postulate that, at low enough temperatures, these fluctuations are localized on t…

Transient start-up dynamics and shear banding in aging soft glassy materials: Rate-controlled flow field

We study the transient start-up dynamics of a fluidity model which captures the rheological behavior of aging soft glassy materials, in a rectilinear shear flow upon application of step shear rate. We observe that when the steady state flow curve is non-monotonic the system shows transient and/or apparent steady state shear banding in close qualitative agreement with experimental observations. Due to a competetion between aging and rejuvenation during the start up, we show that there is an apparent steady state banding at large times even for shear rates such that the steady state flow curve a…

A Model for Aging under Deformation Field, Residual Stresses and Strains in Soft Glassy Materials

A model is proposed that considers aging and rejuvenation in a soft glassy material as respectively a decrease and an increase in free energy. The aging term is weighted by inverse of characteristic relaxation time suggesting greater mobility of the constituents induce faster aging in a material. A dependence of relaxation time on free energy is proposed, which under quiescent conditions, leads to power law dependence of relaxation time on waiting time as observed experimentally. The model considers two cases namely, a constant modulus when aging is entropy controlled and a time dependent modu…

玻璃态材料屈服转变处的涌现标度与空间关联

Emergent scales and spatial correlations at the yielding transition of glassy materials

本研究构建含玻璃度与无序度参数的晶格模型，揭示玻璃态材料屈服转变中空间关联长度的涌现规律，阐明无序度对屈服转变突变性的调控机制。

Fracture of glassy materials as detected by real-time Atomic Force Microscopy (AFM) experiments

We have studied the low speed fracture regime for different glassy materials with variable but controlled length scales of heterogeneity in a carefully mastered surrounding atmosphere. By using optical and atomic force (AFM) microscopy techniques we tracked in real-time the crack tip propagation at the nanometer scale on a wide velocity range (1 mm/s and 0.1 nm/s and below). The influence of the heterogeneities on this velocity is presented and discussed. Our experiments revealed also -for the first time- that the crack advance proceeds through nucleation, growth and coalescence of nanometric …

A kinetic theory of plastic flow in soft glassy materials

A kinetic model for the elasto-plastic dynamics of a flowing jammed material is proposed, which takes the form of a non-local -- Boltzmann-like -- kinetic equation for the stress distribution function. Coarse-graining this equation yields a non-local constitutive law for the flow, introducing as a key dynamic quantity the local rate of plastic events. This quantity, interpreted as a local fluidity, is spatially correlated, with a correlation length diverging in the quasi-static limit, i.e. close to yielding. We predict finite size effects in the flow behavior, as well as the absence of an intr…

反应性辅助胶凝材料（SCMs）与再生玻璃的玻璃态结构：XRD和拉曼光谱对其表征的贡献

The glassy structure of reactive supplementary cementitious materials (SCMs) and recycled glass: Contribution of XRD and Raman spectroscopy to their characterization

本研究通过XRD和拉曼光谱对十三种天然及工业辅助胶凝材料进行结构表征，揭示玻璃态解聚程度、环尺寸及化学组成与弥散晕位置的相关性，为水泥脱碳材料筛选提供依据。

Symmetrical field effect and slow electron relaxation in granular aluminium

Conductivity and field effect measurements in thin insulating Al granular films are reported. The occurrence of a symmetrical field effect and of very slow conductance relaxations is demonstrated. They are identical to the electron glassy behaviours already reported in insulating indium oxide thin films. The results suggest that the phenomena are quite general. The study of structurally discontinuous samples should help to understand the origin and mechanism of the glassy behaviour.

玻璃态聚合物中拉伸指数、压缩指数和对数弛豫现象的统一物理框架

Unified physical framework for stretched-exponential, compressed-exponential, and logarithmic relaxation phenomena in glassy polymers

本研究基于两态两时间尺度框架构建Trachenko-Zaccone方程非线性模型，统一解释玻璃态聚合物多种弛豫规律，可还原经典定律并匹配聚苯乙烯相关实验，厘清不同弛豫的物理起源。

Shear Mediated Elongational Flow and Yielding in Soft Glassy Materials

In this work, we study the deformation behavior of thin films of various soft glassy materials that are simultaneously subjected to two creep flow fields, rotational shear flow by applying torque and elongational flow by applying normal force. The generic behavior under the combined fields is investigated in different soft glassy materials with diverse microstructure such as: hair gel, emulsion paint, shaving foam and clay suspension. Increase in strength of one stress component while keeping the other constant, not only leads to an expected enhanced deformation in its own direction, but also …

晶体CsCu$_4$Se$_3$中具有非典型玻璃态现象的跨层高效热输运

Efficient Cross-layer Thermal Transport with Atypical Glassy-like Phenomena in Crystalline CsCu$_4$Se$_3$

本研究通过第一性原理非谐晶格动力学与统一热输运理论，发现晶体CsCu$_4$Se$_3$中相干驱动的热导率主导z轴总热导率，导致宽温度范围玻璃态热输运，并揭示了跨层高效热输运的微观机制。

From Finite-Size and Surface Effects to Glassy Behaviour in Ferrimagnetic Nanoparticles

This chapter is aimed at studying the anomalous magnetic properties (glassy behaviour) observed at low temperatures in nanoparticles of ferrimagnetic oxides. This topic is discussed both from numerical results and experimental data. Ferrimagnetic fine particles show most of the features of glassy systems due to the random distribution of anisotropy axis, interparticle interactions and surface effects. Experiments have shown that the hysteresis loops display high closure fields with high values of the differential susceptibility. Low magnetisation as compared to bulk, shifted loops after field-…

硅基太阳能电池板用玻璃材料：现状与未来

Glassy materials for Silicon-based solar panels: present and future

本文综述了硅基太阳能电池板玻璃材料的环保化与功能化研究，并针对光谱转换器缺乏标准化评估的问题，提出了一套可量化比较盖板玻璃性能的基准框架。

Differential Variance Analysis of soft glassy materials: a direct method to quantify and visualize dynamic heterogeneities

Many amorphous materials show spatially heterogenous dynamics, as different regions of the same system relax at different rates. Such a signature, known as Dynamic Heterogeneity, has been crucial to understand the jamming transition in simple model systems and, currently, is considered very promising to characterize more complex fluids of industrial and biological relevance. Unfortunately, measurements of dynamic heterogeneities typically require sophysticated experimental set-ups and are performed by few specialized groups. It is now possible to quantitatively characterize the relaxation proc…

Glass Transition of the Phase Change Material AIST and its Impact on Crystallization

Engineering phase change materials (PCM) to realize superior data storage devices requires a detailed understanding of crystallization kinetics and its temperature dependence. The temperature dependence of crystallization differs distinctly between crystallizing from the glassy phase and the undercooled liquid (UCL). Hence, knowing the phase from which crystallization occurs is necessary for predicting the switching ability. Here, we measure the glassy dynamics and crystallization kinetics using calorimetry for heating rates spanning over six orders of magnitude. Our results show that the prom…

Evidence of electronic phase arrest and glassy ferromagnetic behaviour in (Nd0.4Gd0.3)Sr0.3MnO3 manganite : Comparative study between bulk and nanometric samples

The effect of doping of rare earth Gd 3+ ion replacing Nd 3+ in Nd0.7Sr0.3MnO3 is investigated in details. Measurements of resistivity, magnetoresistance, magnetization, linear and non linear ac magnetic susceptibility on chemically synthesized (Nd0.7-xGdx)Sr0.3MnO3 shows various interesting features with doping level x=0.3. Comparative study has been carried out between a bulk and a nanometric sample (grain size ~ 60 nm) synthesized from the same as prepared powder to maintain identical stoichiometry. Resistivity of the samples shows strong dependence on the magnetic field - temperature histo…

Nature of glassy magnetic state in magnetocaloric materials Dy5Pd2-xNix (x = 0 and 1) and universal scaling analysis of R5Pd2 (R = Tb, Dy and Er)

We report a systematic investigation of the magnetic and magnetocaloric properties of Dy5Pd2 and Dy5PdNi. Our study on these compounds gave evidence that they exhibit complex magnetic behaviour along with the presence of glass-like magnetic phase. Furthermore, in these compounds both second order and first order phase transitions were present, which were validated through Arrott plots and Landau parameter analysis. AC susceptibility along with time dependent magnetisation study has confirmed the presence of double cluster glass-like freezing in both Dy5Pd2 and Dy5PdNi. These compounds show sig…

剪切作用下软玻璃状材料的连续模型

Continuum modeling of Soft Glassy Materials under shear

本文提出了一种基于空间解析流体性方法的连续模型，用于解释软玻璃状材料在剪切作用下的复杂流动行为，包括应力超调、剪切带和流化时间的标度定律。

直接观测GeTe相变材料中超快非晶-非晶转变：通过键伸长和角弯曲

Electronic excitation of ultrafast collective amorphous-amorphous transitions in glassy phase-change material

通过飞秒电子衍射与时间依赖密度泛函理论分子动力学模拟，直接观测GeTe中超快非晶-非晶转变，表现为0.2 ps内快速Ge-Te键伸长及随后0.5-2 ps时间尺度上的角弯曲。

拓扑自旋冻结在受挫量子材料中的现象

Topological spin freezing in frustrated quantum materials

研究受挫量子材料中非传统玻璃性自旋动力学的出现，揭示拓扑自旋玻璃行为的特征，区分其与传统自旋玻璃和无序磁体，探讨流体自旋模式和自旋阻塞态的作用。

Stability of Glassy and Ferroelectric States in the Relaxors PbMg1/3Nb2/3O3 and PbMg1/3Nb2/3O3-12% PbTiO3

The stability of the disordered glassy phase in the relaxors PbMg1/3Nb2/3O3 and (PbMg1/3Nb2/3O3)0.88(PbTiO3)0.12, called PMN and PMN-PT, was investigated by preparing partially polarized samples and allowing them to age at zero field in the temperature range for which the phase is history-dependent. The PMN-PT polarization would spontaneously increase until long-range order formed, first appearing as giant polarization noise. Thus the thermodynamically stable phase in PMN-PT appears to be ferroelectric. In contrast, a PMN sample lacking the sharp first-order field-driven transition found in so…

Tensorial Constitutive Models for Disordered Foams, Dense Emulsions, and other Soft Nonergodic Materials

In recent years, the paradigm of `soft glassy matter' has been used to describe diverse nonergodic materials exhibiting strong local disorder and slow mesoscopic rearrangement. As so far formulated, however, the resulting `soft glassy rheology' (SGR) model treats the shear stress in isolation, effectively `scalarizing' the stress and strain rate tensors. Here we offer generalizations of the SGR model that combine its nontrivial aging and yield properties with a tensorial structure that can be specifically adapted, for example, to the description of fluid film assemblies or disordered foams.

Microfluidic velocimetry reveals spatial cooperativity in soft glassy flows

Amorphous glassy materials of diverse nature -- concentrated emulsions, granular materials, pastes, molecular glasses -- display complex flow properties, intermediate between solid and liquid, which are at the root of their use in many applications. A classical feature, well documented yet not really understood, is the very non-linear nature of the flow rule relating stresses and strain rates. Using a microfluidic velocimetry technique, we characterize the flow of thin layers of concentrated emulsions, confined in gaps of different thicknesses by surfaces of different roughness. Beyond the cla…

Capriccio方法作为在复杂加载条件下量化玻璃材料断裂性能并具有化学特异性的多功能工具

The Capriccio method as a versatile tool for quantifying the fracture properties of glassy materials under complex loading conditions with chemical specificity

本文应用Capriccio方法耦合分子动力学与有限元，模拟玻璃材料在复杂加载下的断裂，准确计算临界应力强度因子，展示了其在工程尺度断裂模拟中的潜力。

Properties of LiMnBO3 glasses and nanostructured glass-ceramics

Polycrystalline LiMnBO3 is a promising cathode material for Li-ion batteries. In this work, we investigated the thermal, structural and electrical properties of glassy and nanocrystallized materials having the same chemical composition. The original glass was obtained via a standard meltquenching method. SEM and 7Li solid-state NMR indicate that it contains a mixture of two distinct glassy phases. The results suggest that the electrical conductivity of the glass is dominated by the ionic one. The dc conductivity of initial glass was estimated to be in the order of 10-18 S.cm-1 at room temperat…

Coexisting tuneable fractions of glassy and equilibrium long-range-order phases in manganites

Antiferromagnetic-insulating(AF-I) and the ferromagnetic-metallic(FM-M) phases coexist in various half-doped manganites over a range of temperature and magnetic field, and this is often believed to be an essential ingredient to their colossal magnetoresistence. We present magnetization and resistivity measurements on Pr(0.5)Ca(0.5)Mn(0.975)Al(0.025)O(3) and Pr(0.5)Sr(0.5)MnO(3) showing that the fraction of the two coexisting phases at low-temperature in any specified measuring field H, can be continuously controlled by following designed protocols traversing field-temperature space; for both m…

Rheological constitutive equation for model of soft glassy materials

We solve exactly and describe in detail a simplified scalar model for the low frequency shear rheology of foams, emulsions, slurries, etc. [P. Sollich, F. Lequeux, P. Hebraud, M.E. Cates, Phys. Rev. Lett. 78, 2020 (1997)]. The model attributes similarities in the rheology of such ``soft glassy materials'' to the shared features of structural disorder and metastability. By focusing on the dynamics of mesoscopic elements, it retains a generic character. Interactions are represented by a mean-field noise temperature x, with a glass transition occurring at x=1 (in appropriate units). The exact sol…

Formation and growth of shear bands in glasses: existence of an underlying directed percolation transition

The response of glasses to mechanical loading often leads to the formation of inhomogeneous flow patterns that strongly affect materials properties. Among them, shear bands are ubiquitous in a wide variety of materials, ranging from soft matter systems to metallic alloys. Shear banding is associated with strain localization, i.e. the deformation of the sheared glassy solid is localized in space in form of band-like structures. These structures are often precursors to catastrophic failure, implying that a proper understanding of the underlying mechanisms could lead to the design of smarter mate…