Peculiarities in the X-ray Spectral Microanalysis of the Sn?Te?I System

This is an examination of the methodological specificities of the roentgenospectral microanalysis of the Sn Te I system, involving the application of a graphoanalytical method used in the analysis of ternary systems according to data calculated for the binary ones. The calculations were made on an ES 1060 computer in FORTRAN-4. The calculations are for different selection angles of the microanalyzer, and for a broad interval of values of the accelerating voltage. In this manner the method offered is applicable to any type of microanalyzer, and not only to the Cameca MS-46 used by us.     

Isochronal Phase Transformation in Al?Zn?Cu Alloys

Two Al-Zn alloys with 40 wt% and 74wt% Zn, respectively, and copper additions between 0 and 10 wt% were investigated by means of X-ray diffraction methods, X-ray small angle scattering, resistivity, and dilatometric investigations during continuous cooling from 673 K applying a cooling rate of 2 K/min. It was found that copper additions lower the driving forces for the onset of the homogeneous nucleation after crossing the range of homogeneity, but accelerate the formation of the η-phase. The reasons for this facts are discussed.     

A microstructural examination of Zn?Al?Cu alloys

A microstructural examination of a Zn-11 wt% Al-1 wt% Cu alloy in dependence on the applied heat treatment was carried out by means of scanning electron, transmission electron and optical microscopy as well as X-ray investigations.     

Study of the reversible martensitic transformation in Cu?Zn?Al alloy by positron annihilation

The positron lifetime measurement to investigate phase transformations: martensitic phase (MP) ⇔︁ parent phase (PP) in Cu Zn Al alloy has been used. We have observed the generation of new defects by MP → PP transformation; these defects are liquidated by martensitic transformation. This effect is only observed in case of high concentration vacancies in alloy. In order to explain the nature of these defects we take into consideration the supervacancies idea.     

Liquid Phase Epitaxy of SiC in the System Si?Tb?SiC by Temperature Gradient Zone Melting (I). Investigation of Solubilities in the System Si?Tb?SiC

In the paper which is divided into three parts the liquid phase epitaxy of SiC by temperature gradient zone melting with the solvent Si Tb is discussed. In the first part the solubility of SiC at different initial compositions of the Si Tb solvent is studied in the temperature range 2000–2500 K.     

Stabilization of the melt composition in Ga?Al?Sb?As

In this work we present a new effect of stabilization of the Ga Al Sb As melt composition when it is in contact with the GaAs substrate. It was found that the As content in the Ga Al Sb As melt did not depend on the initial Sb concentration when the liquid phase was formed by saturating the Ga Al Sb melt from the GaAs substrate. This effect is supposed to be due to the change in phase equilibria conditions caused by large lattice mismatch between the substrate and the solid in equilibrium with the liquid.     

Untersuchungen der entmischungsprodukte in Al?Zn?Mg-Legierungen mit hilfe der elektronenmikroskopie

In an AlZnMg alloy metastable and stable phases exhibit different structures, coherency- and orientation relations to the Al-matrix. Their characterization and separation by electronmetallographical methods, especially the interpretation of selected area diffraction patterns are described. The correlation between certain heat-treatment parameters and identified heat-treatment products is established. The difference between the two metastable phases η₂ and R₂ is underlined. Models for the geometrical form of the predominant η-orientations according to Löffler et al., Degischer et al., and Buerger are presented.     

The influence of the Mg content and the quenching conditions on the decomposition kinetics of Al?Zn?Mg alloys

By means of resistivity measurements, TEM and microhardness measurements the decomposition kinetics of A1-3 at.% Zn-1.5 at.% Mg and A1-4.5 at.% Zn-x at.% Mg (x = 0.2; 0.5; 1.0; 1.5; 2.25; 3.0) were investigated. For T_a < T_{a, crit} < T_h (T_h: temperature of the rapid homogenous nucleation) in A1-3 at.% Zn-1.5 at.% Mg and A1-4.5 at.% Zn-x at.% Mg (x = 1.0; 1.5; 2.25; 3.0) an inversion of the decomposition kinetics for T_q > T_inv: (T_inv: inversion temperature) was established. This result can be explained with reference to the binding of excess vacancies in dislocation loops. Proceeding from the discrepancy between the experimentally estimated concentrations of vacancies bound in dislocation loops and the concentrations of free vacancies at T_q, calculated by means of the Lomer equation, a model is proposed, which explains the high vacancy concentration of the loops. In terms of this model the values of the migration energy, obtained for A1-3 at.% Zn — 1.5 at.% Mg in the T_a-range 23 °C ≦ T_a ≦ 100 °C, and the shift of the inversion temperatures T_inv towards higher values with increasing T_a are interpreted. The same applies to the influence of the Mg content on the decomposition kinetics in A1-4.5 at.% Zn-x at.% Mg alloys.     

Thermoelectric Behaviour of Some Phases in the In?Se System

The differential e.m.f. of In₆Se₇ single crystals as a function of temperature have been measured. The electron to hole mobility ratio is determined to be μ_n/μ_p = 3.62. The effective masses of electrons and holes are 4.21 × 10⁻³³ kg and 9.01 × 10⁻²⁹ kg, respectively. The diffusion coefficient for holes and electrons as well as the diffusion length of free charge carriers have been determined.     

Peculiarities of columnar structure formation in electrodeposited Co?W films

The microstructure of Co—W films with perpendicular magnetic anisotropy has been investigated. It is shown that the peculiarities of the columnar structure formation and the changes of magnetic and mechanical properties associated with them are accounted for by the electrodeposition conditions and adsorption of the products of electrode reactions at the cathode.     

Effect of Particle Size on the Ice Nucleating Ability of AgI?AgBr?CuI System

The effect of particle size on the ice nucleating behaviour of AgI-AgBr-CuI system has been studied for the first time. Six samples of different molar ratios and five sizes in each sample are considered in the present study. It is found that the nucleation temperature is the highest for particle size in the range of 60 ± 5um.     

Investigations of phase relations in the system CaO?Na2O?K2O?P2O5

The lattice constants of the compound Ca₂NaK(PO₄)₂ have been studied at room temperature using an X-ray powder diffractometer and also in the temperature range from 20 up to 1000 °C by Guinier-Lenné-technology. A hexagonal lattice with the parameters a₀ = 5.4367 Å and c₀ = 7.3125 Å and a cell volume of 187.18 ų has been determined for the high temperature phase, existing from 670 °C upward. At temperatures below 670 °C a superlattice structure is formed by tripling the axis a, a ′, and c so that it results in a hexagonal superlattice structure cell with the lattice constants of a₀ = 16.311 Å and c₀ = 21.939 Å and a cell volume of 5054 ų.     

Thermal Expansion and Superconductivity in Alkali Metal- and Silver-doped Bi?Sr?Ca?Cu?O System

Samples with the nominal composition Bi₂Sr₂CaCu₂O_y with na doped at the Ca site and K doped at the Sr site are prepared by solid state reaction method. From the X-ray diffraction data it is found that all the the samples have exhibited a single phase 2212. The D.C. electrical resistivity data show that for Na-doped samples the T_c (zero) varies from 80 K to 85 K and for K-doped samples it is from 79 K to 82 K. The loss of oxygen from these samples around 400°C was confirmed by high temperature dilatometry. The variation of the thermal expansion coefficient (“α”) with temperature for different alkali dopings are discussed. Also the samples with the nominal composition Bi₄Sr₃Ca₃Cu_4−xAg_xO_y (with x = 0, 0.1, 0.2, 0.3) were studied.