Glass-forming region in the Cd-Si-As system

Preparation of bulk glasses on the Cd-Si-As base is described and the glass-forming region of this system is defined. Temperatures of the characteristic phase transitions are determined by means of DTA. The melting and solidification of CdSiAs₂ are studied in detail and it is shown that they are incongruent and complex.Cukrovarnická 10, Praha 6, Czechoslovakia.The authors thank to Mrs. Beránková for the preparation of the samples and ot Mrs. Míková for performing the X-ray analysis.     

Glass-forming liquids

When liquids are cooled below their melting temperature T_m, sometimes they do not solidify immediately but remain in supercooled state up to temperatures far below the melting point. Under certain conditions, they can solidify into the form of amorphous solids without crystallizing. A supercooled liquid and a amorphous solid are metastable phases, which are not completely understood in terms of structural arrangement and thermodynamic behaviour. But by far the most interesting feature is the glass transition which is the manifestation of a true thermodynamic transition and a dynamic event since a dramatic dynamic arrest intervenes. A unified theory of supercooled liquids and glass transition does not yet exist and, more specifically, the link between the sharp increase of the relaxation time and the correlation length is a question still largely open. This article presents in the most elementary manner a brief overview of this delicate issue.     

Glass-forming ability in laser quenched transition-metal Alloys

The glass-forming ability by laser quenching is investigated for several transition metal systems (Au-Ti, Co-Ti, Cr-Ti, Zr-Ti). Metallic glasses are obtained in the systems Au-Ti, Co-Ti, and Cr-Ti. The results are compared to predictions by several semiempirical criteria of glass-forming ability. Our results indicate that at the cooling rates typical to laser quenching glasses in binary metallic systems form whenever diffusionless crystallization is excluded.     

Theory of the existence of a two-phase region in ternary ordered fcc alloys

The limiting temperatures of the two-phase region in ternary ordered fcc alloys of the quasibinary B₃A-B₃D system are found on the basis of equality of the chemical potentials of the components of the ordered and disordered phases (in the Gorskii-Bragg-William approximation). The effect of the relative magnitudes of the three ordering energies on the nature of the phase diagrams of the ternary ordered alloy is analyzed.Translated from Izvestiya VUZ. Fizika, No. 7, pp. 54–60, July, 1970.     

The resistivity maximum in the ternary spin glass system Au-Cu-Mn

The temperature of the resistivity maximum, T_m, in the ternary spin glass system Au-Cu-Mn has been analysed in terms of Larsen's theory in order to highlight the contribution from the Kondo effect and the RKKY interaction energy to the resistivity maximum in spin glasses. The competition between these two contributions has been effectively illustrated and a good agreement with theory is obtained for samples with varying magnetic and nonmagnetic atom concentration. A comparison of the dependence of T_m and the RKKY interaction energy on the lattice pressure generated due to addition of Au with reported pressure studies on Mn alloys shows that there is a close relation between the lattice pressure and the externally applied pressure.     

Structure of the ternary gallium-indium-tin eutectic system in the liquid state

An x-ray study has been made of the short-range structure of the ternary gallium-indium-tin eutectic system in the liquid state at T = 288, 308, and 368 °K. Intensity curves were compared with the diffraction reflections of the components. The radial distribution of atoms was calculated. This distribution is interpreted for model quasieutectic and statistical distributions of the scattering atoms. Near the melting point, the distribution of In, Ga, and Sn atoms in the alloy consisting of 62% Ga, 25% In, and 13% Sn (by weight) is quasieutectic, and a transition occurs to a homogeneous physical solution as the temperature is increased.Translated from Izvestiya VUZ. Fizika, No. 10, pp. 22–25, October, 1969.     

Thermodynamics and phase stabilities of the ternary system Li-In-Sb

Electrochemical investigations of the phase equilibria of the ternary system Li-In-Sb show the existence of two new ternary phases, Li₃InSb₂ and nominally Li₆InSb₃ which has a wide range of stoichiometry along the quasi-binary cut InSb-Li₃Sb. Both compounds are stable in equilibrium with elemental indium and antimony. The lithium activities are limited to ranges from 6.6×10^–8 to 3.6×10^–7 and 9.3×10^–8 to 1.1 ×10^–5, respectively, at 400 °C. The standard Gibbs energies of formation of Li₃InSb₂ and Li₆InSb₃ are –296.2 and –568.8 kJ/mol, respectively, at 400 °C and ideal stoichiometry. The activity ranges of Li, In and Sb are given for the stability of all phases of the ternary system.On leave from Institut für Physikalische und Theoretische Chemie, Technische Universität Graz, Austria     

Theoretical issues of steady non-ideal detonation in the ternary nitromethane-ammonium perchlorate-aluminum system

A 1D model of steady non-ideal detonation in the ternary nitromethane-ammonium perchlorate-aluminum systems enriched with aluminum is developed. The model is confirmed by its comparison with the experimental data on detonation of two- and three-component mixtures. The presence of a significant unburnt fraction of the components at the Chapman-Jouguet plane is shown.     

Electron Energy Loss Spectroscopy study of the near surface region of the ternary Co-Cr-Mo alloy

Nature of the characteristic electron energy losses in the second electron emission spectra from the ternary Co-Cr-Mo alloy surface are studied in the low energy range of the primary electron energy E₀. The main types of losses were found: surface and bulk plasmons and their hybrid modes, interband transitions and ionization losses. For Co, Cr, Mo and Co-Cr-Mo alloy the experimental values of the plasmon energy were established to be less than it was predicted by free-electron gas model. Excess of conductive electrons in the surface layers for Co, Cr and Mo was observed by dependence of the surface plasmon dispersion from E₀, while for Co-Cr-Mo alloy the situation is quit opposite. Such behavior is explained by the complex phase structure of the ternary alloy. The analysis of intensity lines of plasmons from E₀ showed deeply changed alloy profile. Ionization Spectroscopy was used for studying the alloy elements distributing on the depth. Mo atoms preferred segregation in the outermost layers of Co-Cr-Mo alloy and enrichment with Cr competitive atoms in underlayers is displayed.     

Utilization of spatial ternary coding scheme in optical CDMA system

In this paper, we propose a spatial ternary coding scheme for optical code-division multiple access systems. Since the multiple access interference (MAI) and beat noise leads to the error floor effect, using error correction mechanism is a preferable manner to further enhance the system performance. The proposed spatial ternary coding scheme possesses larger free distance, which is an effective way to relieve such deteriorating effect. It is expected that more users accommodated in the network can obtain higher throughput, while the side effects of MAI and beat noise will turn out to be more serious. To further reduce such adverse impact, the optical hard-limiter is also proposed. Once the channel condition is improved, it will give rise to the more powerful utilization of error correction code. The countermeasures utilized in the proposed system can effectively fight against the MAI and beat noise, and can allow more simultaneous users accommodated in the network. Therefore, it is a promising way for future high-speed optical access networks.     

Synthesis of ternary compound in H-S-Se system at high pressures

The chemical reaction products of elemental sulfur (S), selenium (Se), and molecular hydrogen (H₂) at high pressures and room temperature are probed by Raman spectroscopy. Two known compounds H₂S and H₂Se can be synthesized after laser heating at pressures lower than 1 GPa. Under further compression at room temperature, an H₂S-H₂Se and an H₂S-H₂Se-H₂ van der Waals compounds are synthesized at 4 GPa and 6 GPa, respectively. The later is of guest-host structure and can be identified as (H₂S)_x(H₂Se)_(2-x)H₂. It can be maintained up to 37 GPa at least, and the stability of its H₂Se molecules is extended:the H-Se stretching mode can be detected at least to 36 GPa but disappears at 22 GPa in (H₂Se)₂H₂. The pressure dependence of S-H and Se-H stretching modes of this ternary compound is in line with that of (H₂S)₂H₂ and (H₂Se)₂H₂, respectively. However, its hydrogen subsystem only shows the relevance to (H₂S)₂H₂, indicating that this ternary compound can be viewed as H₂Se-replaced partial H₂S of (H₂S)₂H₂.     

Ultrasonic propagation in multicomponent system in the critical region

Ultrasonic propagation in a system consisting of coconut oil and carbon tetrachloride has been considered as a function of temperature nearTc in the low MHz region. A small velocity dispersion is seen in the system. The experimental results have been analysed with recent theories developed by Ferrell and Bhattacharjee. The data on attenuation per wavelength nearTc agree with the scaling relation developed by Kroll and Ruhland.     

玻璃化液体中构型熵与展宽弛豫函数关系的研究

运用Adam Gibbs关于构型重排区域的构型熵理论和极值动力学模型得到的弛豫时间的理论公式,提出了KWW型弛豫函数中的非指数展宽因子等于液体中构型重排区域的相对构型熵;并与一个构型重排区域内构型变换的临界分子数成反比,从而赋予了展宽因子新的关于玻璃化结构的物理意义,建立了结构弛豫与构型熵之间的关联.为了消除Vogel Fulcher Tamann方程拟合粘度实验数据在高温区的偏差,用温度的高阶项修正展宽因子与温度的关系,其结果在低于200K时符合得很好,其修正项等效于等压与等容热容量之差对构型熵的修正.