PbX2（X：I,Br,Cl）基非氟卤化物玻璃的形成行为

为了获得具有实用意义的非氟卤化物玻璃，有必要探索新的玻璃形成系统，本文获得了 新的Ｃ ＰｂＸ２（Ｘ：Ｉ，Ｂｒ，Ｃｌ）为基质的三元非氟卤化物玻璃形成系统，并且首次发现ＰｂＩ２可以单独形成玻璃，所得的三元玻璃形成系统均表现出了良好的玻璃形成能力，此外，还从晶体结构，化学键的特怀，离了半径应电负性等角度探讨了各卤化物在玻璃形成过程中所坊的作用，结果表明，这些因素对玻璃形成均具有重要的作用。     

New insight on glass-forming ability and designing Cu-based bulk metallic glasses: The solidification range perspective

In this paper, a new equation was rationally generalized from the reduced glass transition temperature. This equation indicates that solidification range can be used for describing glass-forming ability, which can be calculated with the aid of computational thermodynamic approach. Based on this scenario, several new Cu-based bulk metallic glasses in the ternary Cu–Zr–Ti alloy system were discovered. The as-cast samples were characterized by X-ray diffraction and transmission electronic microscopy. The results indicate that as-cast samples have monolithic amorphous nature. Thermal analysis validates that the smaller solidification range is closely related to the higher glass-forming ability, which is contributed to the effect of solidification time on the formation of bulk metallic glasses. This work also suggests that solidus can influence glass formation.     

Glasses based on fluorides of metals of the I–IV groups: Synthesis,properties, and application

A review of the current studies on the synthesis, glass formation, structure, and optical properties of fluoride glasses in various glass-forming systems is presented. With a view to form and select active optical media for broad spectrum lasers, extensive studies are conducted to clarify the fluorescence mechanisms in fluoride glasses of various compositions doped with REE activators. Studies on obtainment of REE-activated fluoride transparent glass ceramics are discussed. Promising directions of practical application of such materials in optics and laser technology are shown.     

Cast bulk ZrTiAlCuNi amorphous alloys

Cylindrical bulk amorphous samples with diameters up to 10 mm have been prepared by casting ZrTiAlCuNi alloys in a copper mould. In order to rank glass-forming ability as a function of alloy composition, alloys were also cast into wedge-shaped moulds; to a first approximation, the thickness of the amorphous region obtained can be taken as an indication of glass-forming ability. The compositions which lead to the production of bulk glasses all have reduced glass transition temperatures in excess of 0.65 and the extremely high glass-forming ability of these compositions is discussed. We suggest that both the Al and Ti contents are determining factors for the production of bulk amorphous samples and these are believed to reduce the driving force for, and hence the rate of, crystallisation. These amorphous alloys have been found to display high thermal stability and can be annealed for several minutes in the supercooled liquid region. They are ductile at room temperature and have a high value of yield stress.     

Monte Carlo simulation of model spin systems

In this paper, applications of the Monte Carlo technique to estimate the static and dynamic properties of model spin systems are discussed. Finite-size effects and choice of boundary conditions in simulating different types of real systems are outlined. Various applications of the Monte Carlo simulations to one-, two- and three-dimensional Ising models and Heisenberg models are dealt with in some detail. Recent applications of the Monte Carlo method to spin glass systems and to estimate renormalisation group critical exponents are reviewed. Communication No. 19 from the Solid State Structural Chemistry Unit.     

A novel Monte Carlo simulation method for Ising systems

We propose a Monte Carlo method to obtain the thermodynamic functions of Ising systems. We perform a random sampling of spin configurations to determine the degeneracy of the energies of the system, from which an approximant to the partition function is determined. The main advantage of the method over conventional Metropolis lies in the fact that only a single Monte Carlo run is needed to obtain results valid for all temperatures, magnetic fields, and coupling parameters (FM or AFM). As an illustration of the method, we present results for the Ising model in a magnetic field on a 8x8 lattice. The method can be adapted to tackle the random field Ising model (RFIM), the dilute Ising model, and the Ising spin glass, in any spatial dimension.     

Monolithic glass formation by chemical polymerization

Historically, glasses have been formed by solidification of oxide melts from elevated temperatures. Recently it has been demonstrated that monolithic oxide glasses can be formed by chemical polymerization at low temperatures. By the use of this technique, high-temperature reactions such as crystallization, phase separation, etc., which restrict glass formation in certain systems and regions, can be largely avoided. Thus, the technique not only permits investigation of glass structure from a fundamentally different point of view, but also allows the formation of new glasses which can not be formed by thermal means.In this work, the nature of inorganic network formation by chemical polymerization is described. The method of preparing polymerizable active species in a soluble state and general considerations that must be observed to prevent incoherent self-condensation of glass-forming species during hydrolysis and polymerization are discussed. Certain characteristic properties of materials formed by chemical polymerization are also included.     

非晶态高分子粉体玻璃化转变温度的影响因素及测试技术

非晶态高分子粉体的玻璃化转变温度，是分析其结块原因、采取预防结块措施的重要依据。本文分析了影响非晶态高分子粉体玻璃化转变温度的主要因素；介绍了常用玻璃化温度测试技术；建立了用膨胀法测试非晶态粉体玻璃化转变温度的装置与方法，并讨论了其有效性与准确性。     

Mechanical alloying—a novel synthesis route for amorphous phases

Mechanical alloying (MA) pioneered by Benjamin is a technique for the extension of solid solubility in systems where the equilibrium solid solubility is limited. This technique has, in recent years, emerged as a novel alternate route for rapid solidification processing (RSP) for the production of metastable crystalline, quasicrystalline, amorphous phases and nanocrystalline materials. The glass-forming composition range (GFR), in general, is found to be much wider in case of MA in comparison with RSP. The amorphous powders produced by MA can be compacted to bulk shapes and sizes and can be used as precursors to obtain high strength materials. This paper reports the work done on solid state amorphization by MA in Ti-Ni-Cu and Al-Ti systems where a wide GFR has been obtained. Al-Ti is a classic case where no glass formation has been observed by RSP, while a GFR of 25–90 at.% Ti has been obtained in this system, thus demonstrating the superiority of MA over RSP. The free energy calculations made to explain GFR are also presented.     

Ising Spins in a Tridimensional Percolating System with Noninteger Fractal Dimension—Real Lattice

In an artificial 3D percolation medium, the clusters filled by the Ising magnets give rise to a topologically nontrivial magnetic structure, leading to new features of the critical phenomenon even without an external magnetic field. We show that in such an inhomogeneous system, the standard Ising model is strongly modified by the spatial percolation cluster distribution. The case of the real lattice with random shift of the nodes and random radius of voids is discussed, also.     

Magnetic imaging of a supercooling glass transition in a weakly disordered ferromagnet

Spin glasses are founded in the frustration and randomness of microscopic magnetic interactions. They are non-ergodic systems where replica symmetry is broken. Although magnetic glassy behaviour has been observed in many colossal magnetoresistive manganites, there is no consensus that they are spin glasses. Here, an intriguing glass transition in (La,Pr,Ca)MnO3 is imaged using a variable-temperature magnetic force microscope. In contrast to the speculated spin-glass picture, our results show that the observed static magnetic configuration seen below the glass-transition temperature arises from the cooperative freezing of the first-order antiferromagnetic (charge ordered) to ferromagnetic transition. Our data also suggest that accommodation strain is important in the kinetics of the phase transition. This cooperative freezing idea has been applied to structural glasses including window glasses and supercooled liquids, and may be applicable across many systems to any first-order phase transition occurring on a complex free-energy landscape.     

Statistical mechanical modeling of glass-forming systems: A practical review considering an example calcium silicate system

The Glass Genome has only started to be explored. To advance the next generation design of glasses, both physics-informed and data-driven models must be widely available and understood. The most common difficulty in materials modeling is determining which are the simplest approaches appropriate for understanding and predicting key properties. The structure and properties of any material, including its thermodynamics and kinetics, originate from its underlying statistical mechanics. In this work, we present a tutorial view of statistical mechanical modeling of glass, covering structural predictions, structure-property relationships, and the complex kinetics of the glass-forming systems. While the approach presented herein is general and can be applied to any liquid or glassy system, we select calcium silicates as a specific example for this step-by-step review. We hope that this tutorial will be especially beneficial to those who are new to the modeling of glass-forming materials. A list of open questions related to the modeling techniques is also discussed.     

高强度Cu基块状非晶合金的最新研究进展

Cu基块状非晶合金是一种新型高性能材料,从合金体系、力学性能、合金过冷液体区域的性能及非晶形成能力几方面对Cu基块状非晶合金的最新研究进展进行了综述,并展望了新型Cu基块状非晶合金的工程应用前景.     

Two Dimensional Josephson Junction Arrays

Two dimensional Josephson junction arrays (JJAs) offer theopportunity to study a variety of basic physical concepts. Thepresent review focuses on recent experimental work on thedynamics of JJAs, as characterized by ac conductancemeasurements. The review starts with a discussion of basicphysics necessary to describe JJAs. Some experimentalissues, array fabrication and measurement techniques areconsidered next. In a perpendicular magnetic field, a JJA isan experimental realization of the frustrated XY model, withthe frustration parameter f, corresponding to the number offlux quanta in a unit cell of the array, adjusted by themagnetic field. It is thereby possible to investigate thenature of the ground states at arbitrary frustrations. Phasetransitions are the next topic: the vortex unbindingtransition is observed at integer f-values, while, if thejunction coupling energies are appropriately varied across thearray, at half-integer f-values the Ising transition,associated with chiral symmetry breaking, may be observed.Some aspects of vortex dynamics, a subject which is not yetcompletely understood, are then considered. Under certainconditions there is virtually no pinning in JJAs, they aretherefore ideally suited for the study of vortex dynamics. Thenext topic of this review is concerned with the influence ofdisorder on the ground states and on the phase transitions inJJAs. Site percolation in JJAs has provided some insightsinto the physics of disordered systems and allowed to verifysome theoretical predictions on percolation in two dimensions.A quick look at JJAs in the underdamped regime concludesthis review.     

The elastic properties, elastic models and elastic perspectives of metallic glasses

Bulk metallic glass (BMG) provides plentiful precise knowledge of fundamental parameters of elastic moduli, which offer a benchmark reference point for understanding and applications of the glassy materials. This paper comprehensively reviews the current state of the art of the study of elastic properties, the establishments of correlations between elastic moduli and properties/features, and the elastic models and elastic perspectives of metallic glasses. The goal is to show the key roles of elastic moduli in study, formation, and understanding of metallic glasses, and to present a comprehensive elastic perspectives on the major fundamental issues from processing to structure to properties in the rapidly moving field.A plentiful of data and results involving in acoustic velocities, elastic constants and their response to aging, relaxation, applied press, pressure and temperature of the metallic glasses have been compiled. The thermodynamic and kinetic parameters, stability, mechanical and physical properties of various available metallic glasses especially BMGs have also been collected. A survey based on the plentiful experimental data reveals that the linear elastic constants have striking systematic correlations with the microstructural features, glass transition temperature, melting temperature, relaxation behavior, boson peak, strength, hardness, plastic yielding of the glass, and even rheological properties of the glass forming liquids. The elastic constants of BMGs also show a correlation with a weighted average of the elastic constants of the constituent elements. We show that the elastic moduli correlations can assist in selecting alloying components with suitable elastic moduli for controlling the elastic properties and glass-forming ability of the metallic glasses, and thus the results would enable the design, control and tuning of the formation and properties of metallic glasses.We demonstrate that the glass transition, the primary and secondary relaxations, plastic deformation and yield can be attributed to the free volume increase induced flow, and the flow can be modeled as the activated hopping between the inherent states in the potential energy landscape. We then propose an extended elastic model to understand flow in metallic glass and glass-forming supercooled liquid, and the model presents a simple and quantitative mathematic expression for flow activation energy of various glasses. The elastic perspectives, which consider all metallic glasses exhibit universal behavior based on a small number of readily measurable parameters of elastic moduli, are presented for understanding the nature and diverse properties of the metallic glasses.     

Dynamic properties of spin cluster glass and the exchange bias effect in BiFeO3 nanocrystals

A spin cluster glass behavior and a complicated exchange bias effect are observed in high quality BiFeO(3) nanocrystals grown by a hydrothermal method. The dynamic properties of the spin clusters investigated by measuring the frequency dependences of ac susceptibility show that the relaxation process can be described using a power law with the glass transition temperature T(g) = 57 K, relaxation time constant τ(0) = 4.4 × 10(-10) s, and critical exponent zv = 10.3 ± 1.9, consistent with a three-dimensional Ising spin glass. The exchange bias field (H(EB)) varies non-monotonically with temperature and achieves a minimum at T(g). The abnormal shift of hysteresis loops above T(g) may be interpreted in terms of a Malozemoff's random-field model with a framework of antiferromagnetic core/spin-cluster shell structure and a two-dimensional diluted antiferromagnet in a field (2D-DAFF) model, respectively. The exchange anisotropy of the BiFeO(3) nanocrystals will shed light on a possible application for magnetism related nanosized devices.     

Phase Stability in Nanostructures

Nanostructured materials provide access to tailor‐made materials properties by microstructural design. Excellent mechanical properties such as high strength or wear resistance are often found in nanocrystalline materials. For magnetic materials, the design of nanostructured composites offers advantages if the structural scales match the intrinsic magnetic length scales. In some cases, as in the new nanocrystalline soft magnetic alloys, the combination of amorphous and nanocrystalline phases is necessary to obtain the desired properties. This rises the question of the limiting size for a stable crystalline structure, especially in contact with an amorphous phase. These considerations, which have been of interest for basic research in the context of the microcrystalline model for amorphous materials, are of technical importance for the optimization of nanostructured composites. Recent model experiments about the stability of thin Fe‐based glass forming alloy films are reviewed. A relationship between phase stability, composition, and interface density has been established. The implications of the results for the design of nanostructured alloy systems are discussed.     

Charge Ordering and Spin Gap Transitions in Quarter-Filled Ladders

Several new families of charge transfer solids with ladder-like structure show unusually high spin gap transition temperatures. We argue that these materials are best described by a 1/4-filled ladder with zigzag interstack bonds. We find that in the 1/4-filled zigzag ladder, a cooperative bond-charge ordering leads to the formation of local singlets and a spin gap. The spin gap for the zigzag ladder is an order of magnitude larger than that found in equivalent one dimensional systems.     

Dynamics and mechanics below the glass transition: The non-equilibrium state

There is much interest in the dynamics of glass-forming systems above the glass transition temperature. However, in many applications the behavior of the systems needs to be understood in the glass-transition T_g range and particularly in the non-equilibrium state. We present a set of empirical observations for the dynamics of material behaviors near to, but below the glass transition for polymer glass formers and outline a “minimal” set of requirements that might be expected of computer simulations in the non-equilibrium glass near to T_g. The survey includes the kinetics and nonlinearity of the structural (volume or enthalpy) recovery of the glass and its impact on the mechanical response (physical aging). These are presented with the thought that computer simulations may well be able to provide insights to the origins of an extremely complicated set of experimental observations.

Additionally, we present some results of glass formation of simple liquids constrained to nanometer size pores with the expectation that such experiments may be readily simulated because of the small number of molecules in such pores.     

Slow motion of confined molecules: NMR and broadband dielectric spectroscopy investigations

Nuclear magnetic resonance (NMR) and broadband dielectric spectroscopy are used to investigate the dynamics of small glass-forming molecules confined to restricted geometries. Ethylene glycol molecules are embedded in the supercages of NaX zeolites. The combined application of NMR and broadband dielectric spectroscopy advances the understanding of the slowing down of the motion near the glass transition temperature of these confined molecules. In combination with nuclear spin relaxation and nuclear magnetic resonance spectroscopy, dielectric relaxation studies on glass forming molecules allow conclusions on the character of the motion. High resolution 1H magic angle spinning (MAS) NMR measurements not only enable a characterisation of the state of the adsorbed molecules via a chemical shift analysis. By means of an analysis of MAS spinning sidebands we may also estimate a correlation time the meaning of which will be discussed in comparison to the results of longitudinal proton spin relaxation measurements. In addition to broadband dielectric spectroscopy slow molecular motions of partially deuterated ethylene glycol adsorbed in NaX are studied by means of 2H NMR line-shape analysis.