NEW THERMODYNAMIC DATA FOR La1.8Ba0.2CuO4-δтезисы доклада

Дата последнего поиска статьи во внешних источниках: 22 ноября 2015 г.

Работа с тезисами доклада


[1] New thermodynamic data for la1.8ba0.2cuo4-δ / E. I. Belova, L. A. Tiflova, A. S. Monayenkova, V. A. Alyoshin // Abstracts of the XX International Conference on Chemical Thermodynamics in Russia (RCCT-2015, June 22-26, 2015, Nizhni Novgorod). — Lobachevsky State University of Nizhni Novgorod Nizhni Novgorod, 2015. — P. 86–86. The lanthanum barium cuprate La2−xBaxCuO4−δ with K2NiF4 structure is known as the first hightemperature superconductor. The barium has a high ability for carbonate contamination that can influence on sample properties. The introduction of carbonates in the crystal structure may take place from start reagents or atmosphere air. For comparison the synthesis was carried out in the same condition using BaCO3 or BaO2 as a start reagents. In both cases the single phase samples were obtained differ in c cell parameters, but according to FTIR study the introducing of carbonate groups in crystal lattice may take place when BaCO3 was used. The use of pure BaO2 allowed obtaining the La1.8Ba0.2Cu3.91 sample without carbon contamination. The measurements of the reaction heat of La1.8Ba0.2CuO4-δ with 1 M HCl were performed at 298.15 K in a sealed swinging calorimeter with an isothermal jacket. The enthalpy of La1.8Ba0.2Cu3.91 formation obtained from BaO2 is differ from known reference data (Table) almost on 14 kJ/mol, while the enthalpy of carbonate contaminated sample formation is close to them. So, the carbonate contamination, which undetectable by X-ray study, may significantly influences on thermodynamic properties of barium-containing compounds.

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