Physicochemical study on selenites of the three-component system Yb2O3-SeO2-H2O

The solubility isotherm of the three-component system Yb₂O₃-SeO₂-H₂O at 100°C was studied. There are two fields of crystallization in the solubility diagram at this temperature - a small one of Yb₂(SeO₃)₃·4H₂O and a large one of YbH(SeO₃)₂·2H₂O. These compounds were identified by the Schreinemakers' method, and by chemical and X-ray analyses as well. Simultaneous TG and DTA curves of the two compounds obtained were made and the mechanism of the thermal decomposition was described. This revised version was published online in July 2006 with corrections to the Cover Date.     

Spectrochemical Determination of Microimpurities in Mercury

Abstract

Mercury together with the microimpurities in it had been turned into iodides in advance in a vacuum ampule in the presence of collector - spectrally pure carbon powder, containing 2 per cent Li (as Li₂CO₃). The obtained mercury (II) iodide was separated from the microimpurities by sublimation at 100°C and the collector with the microimpurities was subjected to spectral analysis. The method allows the determination of 20 elements in mercury within detection limits of 10^?5 to 10^?7% and relative standard deviation 0.08 to 0.25. The method can be applied for the analysis of mercury (II) iodide, too.     

Growth and characterization of large La1‐xPbxMnO3+δ (x=0.32–0.35) crystals

Large crystals of La_0.63Pb_0.37Mn O_3+δ with small La(Pb)‐ deficiency of about 0.005‐0.01 at.% were grown by high temperature solution growth method. The structure of the grown crystals was determined as rhombohedral with R‐3 space group by single‐crystal X‐ray diffractometry. The surface morphology of the crystals and the exact chemical composition was examined by scanning electron microscopy and energy dispersive X‐ray analysis methods, respectively. The IR‐transmission spectrum reveals the presence of Mn³⁺O₆‐ and Mn⁴⁺O₆‐ octahedra in the lattice of La_0.63Pb_0.37Mn O_3+δ crystals. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,crystallographic data and thermostability of some metal ortho-tellurates of the type Me3TeO6 and Me2TeO6

A method of synthesis of some metal ortho-tellurates of the type Me₃TeO₆ and Me₂TeO₆ was developed. Crystallographic data (parameters of the elementary cell and the number of the formula units of these compounds) were calculated. Their picnometric density and X-ray density were determined and compared. The thermostability of these ortho-tellurates was studied.     

The boundary integral equation method applied to shallow membrane shells of positive Gaussian curvature

The boundary integral equation method (BIEM) is developed for the analysis of shallow membrane shells with positive Gaussian curvatures. Shells with constant thickness and constant curvatures are considered. In the infinite domain, fundamental solutions are obtained which correspond to generalized concentrated tangential forces in the x and y coordinate directions. The Betti-Maxwell reciprocal theorem and Green's second identity are used to obtain the boundary integral equations of the solution presented.This approach, which is applied for the first time in membrane shell theory, seems to be a powerful alternative to domain type methods. Shells with various boundary conditions, loadings and arbitrary plan forms can be considered. It is also possible to add the effects of thermal fields and openings in the shells.The potential of the method is demonstrated by means of a worked example.     

Growth and Optical Absorption of Photorefractive Bi12SiO20 Crystals Doped with Zn and Cd and Co-doped with P

Single crystals of Bi₁₂SiO₂₀ (BSO) Zn- and Cd-doped and co-doped with P have been grown by Czochralski technique and optimum conditions for producing optically homogeneous crystals were established. The transmission and reflection spectra have been measured in the range 0.38–0.85 μm and absorption coefficients have been determined. The Zn dopants have been found to bleach the crystals and decrease the transmission shoulder, whereas Cd dopant increases the absorption and makes the shoulder well pronounced. P-doping strongly decreases the transmission shoulder and shifts absorption to shorter wavelengths. The absorption Coefficient of BSO doped with P has been found to decrease with dopant concentration increase up to 3 mol% P and above it increases with P concentration in the whole studied range. Zn + P- and Cd + P-co-doping (P concentration in the crystal less than 3 mol%) decreases strongly the absorption coefficient and shifts the spectra to short wavelengths.     

Study of the crystallization fields of cobalt(II) slenites in the system CoSeO<Subscript>3</Subscript>-SeO<Subscript>2</Subscript>-H<Subscript>2</Subscript>O

Summary The solubility of CoSeO₃-SeO₂-H₂O system in the temperature region 298-573 K was studied. The phase diagram of cobalt(II)selenites was drawn and the crystallization fields for the different phases were determined. Depending on the conditions for hydrothermal synthesis, CoSeO₃×2H₂O, α-CoSeO₃×1/3H₂O, β-CoSeO₃×1/3H₂O, CoSeO₃, Co(HSeO₃)₂×2H₂O and CoSe₂O₅ were obtained. The different phases were proved and characterized by chemical and X-ray analyses, as well as IR spectroscopy.