No abstract available

[en] The equilibrium constant has been calculated for the reaction of strontium sulfate with ammonium carbonate in an aqueous medium (K=68.85) and the degree of SrSO₄ conversion to SrCO₃ (epsilon=98.56%). The interaction of calcium and strontium sulfates with (NH₄)₂CO₃ in an aqueous solution has been studied depending on time of stirring the pulp and the ratio between the reagents. It has been established that under identical conditions epsilonsub(Ca)>epsilonsub(Sr). This difference has been explained by the law of mass action and the capability of ZrSO₄ to form hardly soluble double compounds of the (NH₄)₂SO₄xSrSO₄ type. The presence of silicon impurity has been shown to adversely affect the interaction between calcium and strontium sulfates with (NH₄)₂CO₃; iron and aluminium practically do not affect the efficiency of the process

[en] Short note

[en] The DTA, roentgenography, IR- and Raman spectroscopy methods have been applied to study phase formation in the Nb₂O₅-TiO₂ system. The samples are prepared by coprecipitation from solutions. The formation of TiO₂xNb₂O₅ and 2TiO₅x5Nb₂O₅ compounds is found. The phase diagram of the system is plotted. The liquidus curve is charaterized by three eutectics at 93.3, 62.0, 42.0 mol.% Nb₂O₅ and melting temperatures 1440, 1430, 1445 deg C, respectively

[en] The composition and optical parameters of thin-layer vacuum condensates of lanthanide stannates were studied. The fact of the coating enrichment by tin oxides as compared with initial materials was confirmed. The values of refractive index and forbidden zone width calculated from the spectra of absorption and reflection of the coatings are 1.9-2.3 and 2.6-3.0 eV respectively, which indicates a considerable deficiency of the oxides as regards oxygen. The degree of the coating deficiency is the lower the higher is stabilization of tin valency state in lanthanide stannates

[en] Phase formation in Y₂O₃-Nb₂O₅ system was investigated. Samples were prepared by coprecipitation from solutions. Formation of two chemical compounds 3Y₂O₃xNb₂O₅ and YNbO₄ - was establised. State diagram in 900-2400 deg C range was plotted