The thermodynamic stability and hydration enthalpy of strontium cerate doped by yttrium

The standard molar enthalpy of formation of SrY0.05Ce0.95O2.975 has been derived by combining the enthalpy of solution of this compound in 1 M HCl + 0.1 KI obtained by us and auxiliary literature data. The following value has been derived: DfH (SrY0.05Ce0.95O2.975, s, 298.15 K) = -1720.4 (3.4) kJ/mol. The obtained value has been used to obtain the formation enthalpy of SrY0.05Ce0.95O2.975 from the mixture of binary oxides (DoxH (298.15 K) = -45.9 (3.4) kJ/mol) and formation enthalpy of reaction of SrY0.05Ce0.95O2.975 with water forming Sr(OH)2, CeO2, Y2O3 (DrH (298.15 K) = -85.5 (3.4) kJ/mol). Data obtained by solution calorimetry and additional information on the entropies of different substances have shown that SrY0.05Ce0.95O2.975 is thermodynamically stable with respect to a mixture of SrO, Y2O3, CeO2 and that the reaction of SrY0.05Ce0.95O2.975 with water is thermodynamically favourable.Comment: 7 pages, 12 reference

Magnetic properties of bismuth-cobalt oxides doped by erbium

We synthesized bismuth - cobalt oxide doped by erbium with general formula Bi3-xErxCoO3-y. Compound has structure of delta-form bismuth oxide. Magnetic properties of the compound were measured by Faraday's method using quartz scales in the temperature range of 80-500 K. The magnetic susceptibility and effective magnetic moment were calculated.Comment: 5 pages, 2 figure

Formation enthalpy of BaCe0.7Nd0.2In0.1O2.85

In this paper for the first time we synthesized the compound BaCe0.7Nd0.2In0.1O2.85 by solid-state reaction. The phase has orthorhombic structure (space group Pmcn). We also measured the standard formation enthalpies of BaCe0.7Nd0.2In0.1O2.85 by solution calorimetry in 1 M HCl with 0.1 M KI. We determined the stability of Nd(In)-doped barium cerate with respect to mixtures of binary oxides. On the basis of these data we established that above-mentioned mixed oxide is thermodynamically stable with respect to their decomposition into binary oxides at room temperatures. We also established that BaCe0.7Nd0.2In0.1O2.85 oxide is thermodynamically favoured than BaCe0.8Nd0.2O2.9.Comment: 9 page

New phases in the Ba-Ce(M)-O systems (M = Ga, In)

A new and known barium cerates doped by In and Ga were synthesized in air at 1700 K. The synthesis was performed by solid state reactions from BaCO3, CeO2, In2O3 or Ga2O3. X-ray diffraction profiles of the powdered samples were obtained with DRON-UM-1 and STADI-P diffractometers using monochromatized CuKa radiation. The following compositions of new phases were obtained: BaCe1-xGaxO3-d (x = 0.05; 0.1) and BaCe1-xInxO3-d (x = 0.25, 0.5). They crystallize in the orthorhombic space group Pnma. The lattice parameters were calculated by full profile Rietveld method. Based on analysis of literature data it was possible to assume that increasing of tolerance factors from BaCeO3 up to BaCe1-xGaxO3-d (BaCe1-xInxO3-d) led to the increasing of stability and transport properties of Ga and In doped barium cerates.Comment: 8 pages, 2 figures, 3 table

Study of the SmBaCuO solid solutions decomposition and its possible role for changing critical current

We studied thermochemical characteristics of the Sm1+xBa2-xCu3Oy single crystals by solution calorimetry. Dependences of formation enthalpies from samarium content were constructed. It was established that solid solutions on the bases of Sm123 could be decomposed both in inert and in oxygen atmosphere into different mixtures. We supposed that solid solutions decomposition could lead to increasing critical current density. We assumed from thermochemical data that Jc could be greater for samples prepared in oxygen than for samples synthesized in inert atmosphere. We confirmed these assumptions by comparison of obtained thermochemical data with transport properties measured in literature. We also investigated temperature dependences of resistance in the temperature range of 300-550 K during slow heating. As it was shown there was anomaly of resistance near 500 K. The origin of this anomaly was discussed.Comment: 8 pages, 2 figure

Solution calorimetry investigations of new phase BaCe0.6Y0.3In0.1O2.8

The preparation of BaCeO3 doped by yttrium and indium oxides (BaCe0.6Y0.3In0.1O2.8) has been performed by solid-state reaction from BaCO3, CeO2, Y2O3, In2O3. The compound BaCe0.6Y0.3In0.1O2.8 has been synthesized for the first time. The X-ray measurements have showed that BaCe0.6Y0.3In0.1O2.8 has an orthorhombic structure (space group Pmcn). The standard formation enthalpies of BaCe0.6Y0.3In0.1O2.8 have been determined by solution calorimetry combining the solution enthalpies of BaCe0.6Y0.3In0.1O2.8 and BaCl2 + 0.6CeCl3 + 0.3YCl3 + 0.1InCl3 mixtures in 1 M HCl with 0.1 M KI at 298.15 K and literature data. It has been obtained that above-mentioned mixed oxide is thermodynamically stable with respect to their decomposition into binary oxides at room temperatures. It has been also shown that BaCe0.6Y0.3In0.1O2.8 has been more thermodynamically favored than BaCe0.9In0.1O2.95.Comment: 9 pages, 1 figure, 1 table, 24 references. arXiv admin note: text overlap with arXiv:1212.034

Thermodynamic stability of new phase Bi12.5Sm1.5ReO24.5

The Bi12.5Sm1.5ReO24.5 phase has been synthesized for the first time. The preparation of Bi12.5Sm1.5ReO24.5 has been performed by solid-state reaction from Bi2O3, Gd2O3, Re2O7. The X-ray measurements have showed that Bi12.5Sm1.5ReO24.5 was cubic structure (space group Fm3m). The standard molar enthalpy of formation of Bi12.5Sm1.5ReO24.5 has been determined by solution calorimetry combining the enthalpies of dissolution of Bi12.5Sm1.5ReO24.5 and 6.25Bi2O3 + 0.75Sm2O3 + 0.5Re2O7 mixture in 2 M HCl and literature data. It has been obtained that above-mentioned phase is thermodynamically stable with respect to their decomposition into binary oxides at room temperatures.Comment: 9 pages, 1 figure, 2 tables, 15 reference

Decomposition of solid solutions in the Nd-Ba-Cu-O system and its influence on changing transport characteristics

Thermochemical characteristics of Nd1+xBa2-xCu3Oy solid solutions were studied by solution calorimetry. Dependences of formation enthalpies from Nd content were constructed. It was established that decomposition of solid solution on the basis of Nd123 phase took place both in inert and in oxygen atmosphere. As a result of decomposition the different mixtures such as solid solutions with increasing and decreasing Nd content and BaCuO2 were formed. Obtained thermochemical data were compared with results of measurements of transport characteristics. It was established that treatment of samples at 550-600 C led to increasing critical current and decreasing Tc.Comment: 7 pages, 1 figure Keywords: Nd-Ba-Cu-O system; Calorimetry; Decompositio

Preparation and ionic conductivity of new Bi12.5Lu1.5ReO24.5 phase

The substitution of Re into Bi2O3 allows stabilization of the d- Bi2O3 structure by additional substitution of lutetium ion to give phase of composition Bi12.5Lu1.5ReO24.5. The phase was synthesized for the first time. Structural analysis performed by neutron diffraction showed that space group was Fm3m with lattice parameter a = 5.5591(2) {\AA}. The phase has been found to show high ion conductivity at moderate temperature. The conductivity was measured in the temperature range of 600-800 K. The conductivity of Bi12.5Lu1.5ReO24.5 at 800 K is the same as the conductivity of BiCuVOx, Bi12.5Ln1.5ReO24.5 (Ln = Eu, La, Nd) phases. In this connection the Bi12.5Lu1.5ReO24.5 phase offers excellent potential for moderate temperature application

Thermodynamic properties of yttrium cuprate

The standard formation enthalpy and enthalpy from binary oxide of yttrium cuprate have been determined by solution calorimetry combining the solution enthalpies of Y2Cu2O5 and Y2O3 + 2CuO mixture in 6 M HCl at 323.15 K and literature data. The heat capacity of Y2Cu2O5 has been measured by adiabatic calorimetry from 8 up to 303 K. Smoothed values of heat capacities, entropies and enthalpies were calculated on the basis of experimental data. The thermodynamic functions (heat capacity, entropy and enthalpy) at 298.15 K have been calculated. On the basis of obtained data it has been obtained that above-mentioned complex oxide is thermodynamically unstable with respect to their decomposition into binary oxides at room temperatures.Comment: 10 pages; 2 Table