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.     

Cu1—xAgxInSe2 Solid Solutions

CuInSe₂, AgInSe₂, ternary compounds and Cu_1—xAg_xInSe₂ solid solutions were synthesized by one-temperature method. The composition and structure of indicated materials were established by chemical and X-ray analysis methods, lattice constants, values of σ positional parameter and bond lengths were also calculated. Temperatures of phase transformations were determined by differential thermal analysis (DTA) method and phase diagram of AgInSe₂-CuInSe₂ system was built which is characterized by small crystallization interval and presence of solid state transformations throughout the concentration interval.     

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.     

Bulk modulus — volume — ionicity relationship in tetrahedrally bonded semiconductors

It is shown that the bulk modulus of all diamond, zincblende and wurtzite structure compounds can be evaluated by means of the simple relation B = b₀a^−m(1 – g₀f_i) where a is the lattice parameter, f_i the spectroscopically defined bond ionicity and b₀, m and g₀ are constants having the same values for all compounds. This bulk modulus relation is used to estimate the bulk moduli for those zincblende and wurtzite structure compounds for which no experimental measurements have been made until now.     

Gel growth and characterization of β ‐DL‐methionine

DL‐Methionine [C₅H₁₁NO₂S] is one of the essential amino acids in humans. It has two crystalline forms, viz., α‐ and β‐ methionine. In the present study, β ‐ form is crystallized in silica gel; under suitable pH conditions by single diffusion method. The grown crystals were characterized by density measurement and single crystal X‐ray diffraction. Fourier transform infrared (FTIR) spectroscopic studies, thermal analysis and scanning electron microscopic (SEM) studies were also made as part of the structural studies. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

The variable shaping technique — a new method of the sapphire growth

The paper presents results on sapphire growth by a new method which enables one to vary a configuration crystal cross-section during the crystallization process. The field of application of those principally new products is also discussed.     

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 simultaneous crystallization of ZnSnP2/ZnSiP2 — a heterocombination

In the solution growth of ternary semiconductors tin can be used as solvent. In this case the phase purity resp. the generation of a solid solution of the reaction products obtained is of interest. This problem was investigated using the growth of ZnSiP₂ from tin solutions. For characterizing the phases obtained by the growth X-ray diffraction. Mössbauer spectroscopy, electronoprobe analysis, luminescence spectroscopy, DTA-measurements and electrical measurements were used. The results of these measurements allow the following statements within the limits of measuring.

• 1 The growth of the pure ZnSiP₂ from tin melts is possible.
• 2 The phases ZnSnP₂ and ZnSiP₂ are generated side by side by a nonstoichiometric amount weighed of silicon.
• 3 The solubility of ZnSnP₂ in ZnSiP₂ or reverse could not be pointed out.
• 4 The precipitation of ZnSnP₂ on ZnSiP₂ takes place epitaxially.

     

The Molecular and Crystal Structure of 3β-O-(2′,3′ -O-isoropylidene-α-L-rhamnopyranosyl) — digitoxigenin

3β-O-(2′,3′ -O-isoropylidene-α-L-rhamnopyranosyl) — digitoxigenin crystallizes in the monoclinic space group P 2₁ with two molecules C₃₂H₄₈O₈ per unit cell and the lattice constants a = 7.865, b = 6.470, c = 29.803 Å, β = 93.95°. The structure was solved by direct methods of phases determination and subsequently refined by least squares technique to the final R-value 0.06. The position of the lactone ring is disordered in the crystal.     

Phase equilibria in BaB2O4–LiF system and β–BaB2O4 bulk crystals growth

Solid state synthesis, differencial thermal analysis and visual polythermal analysis were applied to study the phase equilibria in BaB₂O₄–LiF system. A phase diagram BaB₂O₄–LiF has been plotted for the first time. The system has proved applicable for growing β–BaB₂O₄ bulk crystals.     

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.     

1,6‐Hexanediammonium Dihydrogendecavanadate Dihydrate, (H3N—(CH2)6—NH3)2H2V10O28 · 2 H2O

The crystal structure of (H₃N—(CH₂)₆—NH₃)₂H₂V₁₀O₂₈ � 2 H₂O consists of dihydrogendecavanadate anion with C_i symmetry, two 1,6‐hexanediammonium cations and two water molecules. The structure has a P space group symmetry with one of the cations in special position; this cation is disordered. The polyanion of most usual protonation type is similar as formed in other known dihydrogendecavanadates.     

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)°.     

Neutronographical investigations of the age hardening behaviour on Iron — Manganese — Nickel alloys

Age hardenable martensitic Iron—Manganese—Nickel alloys were neutronographically investigated in order to explain the age hardening effect occurring during the heat treatment. The formation of coherent precipitations of an ordering phase within the matrix proved to be the reason for the occurring hardness increase.