Study on the Phase equilibrium in the Systems Sodium Selenate — Cadmium Selenate — Water and Sodium Selenate — Manganese Selenate — Water at 25 °C

The phase equilibrium in the systems Na₂SeO₄ CdSeO₄ H₂O and Na₂SeO₄ MnSeO₄ H₂O were studied and it was established that new phases were obtained — double salts with a composition: Na₂Cd(SeO₄)₂ · 2 H₂O and Na₂Mn(SeO₄)₂ · 2 H₂O. The fields of phase equilibrium of the double salts in the triple systems were determined. The composition of the new phases and the number of the water molecules of crystallization were investigated, respectively by the Schreinemackers' method of physico-chemical analysis and thermogravimetrical analysis. An X-ray diffraction analysis of the new phases obtained was done.     

Contribution of Z1-centers in radiation hardening of NaCl: Sm2+ crystals — a study

Microhardness studies on X-irradiated NaCl and NaCl:Sm crystals are studied with varying times of X-irradiation in pre-quenched and quenched crystals. The contribution of Z₁-centers in radiation hardening studies is discussed.     

Thick LPE Layers of InAs1—xSbx for 3—5 μm Optoelectronic Applications

N-InAs_1—xSb_x/n, p-InAs heterostructures were grown by liquid phase epitaxy on (100) oriented substrates. The layer composition was varied in the interval 0 < x < 0.1, the corresponding lattice mismatch being not greater than 0.5%. The layer composition was studied by microprobe analysis on the surface of the structure cross-section. Microhardness profiles were investigated using Vickers and Knoop indentors. Raman scattering was also studied.     

On the structure of α′m-precipitates in Al-Zn alloys

The lattice parameter of the f.c.c. α′-phase in an Al-12at.% Zn alloy decomposed at ageing temperatures ranging between 170 °C and 210 °C was investigated by an analysis of Moiré fringe contrasts which appear inside the precipitates in the TEM-micrographs. Additionally information was gained concerning the relationship between the corresponding lattice of the α′_m-precipitates and the matrix. The analysis proved that the misfit between the lattice of the α′_m-precipitates and the adjoining matrix is fairly small, namely less than 1.5% in lattice spacing and less than 1° in the angular rotation. From these results it was concluded that the major part of the matrix planes passes the precipitates without interruption.     

Synthesis and Characterisation of Bulk Textured Phases in the Bi(Pb)—Sr—Ca—Cu—O System

Growth of lead-doped textured Bi-cuprate, using an immersed heater floating zone (TSFZ) apparatus, from a narrow supercooled melt created an essentially dense structure consisting of locally aligned long platelet crystal grains. The extended grains have their long axes parallel to the growth axis with a low angle misorientation. The effect of gas bubbles and the pulling rates on the microstructure and superconducting transition temperature of the textured boules have been studied. The decomposing nature of the 2223 phase on melting leads to form the energetically favourable low T_c 2212 phase.     

Determination of the phase ranges during cooling and heating of Al-40wt.%—(0—3) wt.% Mg alloys

The various phases and the respective ranges of their existence were determined during continuous cooling from temperatures close below the solidus line to R.T. with a rate of 2 K min⁻¹ as well as during the subsequent heating in few Al Zn(40 wt.%)–Mg(X) alloys (X = 0; 0.5; 1.0; and 3.0 wt.%) by means of X-ray phase-analysis, small angle X-ray scattering, differential thermo-analysis, optical microscopy, and X-ray micro-analysis. The most striking features are that even addition of only 0.5 wt.% Mg cause the formation of precursors of the MgZn₂ equilibrium phase few degrees below the solidus line.     

Chemistry of organic eutectics: Phenanthrene — benzoic acid and phenanthrene — cinnamic acid systems

Solid-liquid equilibrium data for binary systems of phenanthrene with benzoic acid and cinnamic acid, expressed in the form of temperature-composition curves, show the formation of a simple eutectic in each case. Linear velocity of crystallisation (v), studied by capillary method at different undercoolings (ΔT), suggests the applicability of Hillig-Turnbull equation, v = u(ΔT) ⁿ, where u and n are constants depending on the nature of solidification. Data on heats of fusion of pure components and eutectics, determined by the DTA method, infer appreciable interaction among the components in the eutectic melts. To highlight the nature of interactions among the components forming the eutectic melt, the excess thermodynamic functions such as h^E, s^E, and g^E were computed. Microscopic studies reveal that the structure of eutectic is different from those of the parent components. Infrared spectra, recorded in the region, 4000 —625 cm⁻¹, indicate weak interactions among the components in the eutectic.     

The Crystal and Molecular Structure of 11,12‐dibromo‐ 7,8—benzo‐1,5‐di(p—tolylsulphonyl)‐1,5‐diazacyclononan

The crystal structure of the title compound, C₂₅H₂₆Br₂N₂O₄S₂ was determined by single crystal X‐ray diffraction technique. The crystals are monoclinic, space group C 2/c, with a=20.7142(2) Å b=11.7910(2) Å, c= 10.6735(3) Å, β=98.549(2)°, V=2577.94(9) ų, Z=4. The structure was solved by direct methods and refined by least‐squares methods to a final R=0.046 for 1866 observed reflections with I>2sigma(I). The title compound, displays disordered geometry around the C1 atom located almost on twofold axis. The nine‐membered heterocylic ring is close to the half‐chair conformation. The dihedral angle between phenyl rings is 34.2(1)°.     

On the structure of the rhombohedral α′R-phase in Al Zn alloys

The lattice parameters α and α of precipitates of the rhombohedral α′_R-phase grown in two Al Zn alloys with 10 and 12 at.% Zn, respectively, at elevated temperatures were determined by transmission electron microscopy (TEM). Two approximative methods were derived to evaluate the Moiré fringes occuring in the TEM micrographs. The results obtained by these two methods agree within the range of experimental error with those presented in the literature (mainly gained from X-ray methods).     

Dielectric Properties of Superionic System AgBr—PbI2—Ag2O—B2O3

Dielectric properties of the system AgBr—PbI₂—Ag₂O—B₂O₃ has been studied for various temperatures and frequencies. Conductivity of the sample has also been measured and it is found that at 160 °C it attains the value 5.9 × 10^—3 (Ohms cm)^—1 and the activation energy calculated from the Arrhenius is found to be 0.16 eV.     

Composite Microhardness of Quartz — Al Structures

The microhardness-depth profiles of as-obtained and annealed quartz (INFstrate)-Al (film) structures have been investigated. A layer of constant hardness has been detected beneath the initial interface. This is supposed to result from incorporation of aluminium atoms into the surface layer of the INFstrate, reduction of SiO₂ and diffusion of the atoms of a certain element during the processes of preparing and rapid thermal annealing of the structures.     

Magnetic properties of uranium — Transition-metal glasses

Results of resistivity, magnetization and susceptibility measurements are reported on U₆₆T₃₄ where T denotes Fe, Co, or Ni. Magnetic susceptibility data on each of the alloys displayed thermomagnetic-history effects indicating some spin-glass like character. The high-field magnetization data showed a significant non-linearity indicating a contribution to the magnetization from a cluster term. The evidence suggests that these alloys form cluster glasses in which only those T atoms whose local environment is sufficiently dense in T atoms bear a stable magnetic moment.