High-Temperature Enthalpy of La2Hf2O7 in the Temperature Range 490–2120 K
| Autor: | S. M. Lakiza, Ya. S. Tishchenko, A. R. Kopan, N. P. Gorbachuk |
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| Rok vydání: | 2018 |
| Předmět: |
Materials science
Enthalpy Oxide Thermodynamics chemistry.chemical_element 02 engineering and technology Calorimetry 01 natural sciences Heat capacity chemistry.chemical_compound symbols.namesake 0103 physical sciences Materials Chemistry Lanthanum 010302 applied physics Metals and Alloys Atmospheric temperature range 021001 nanoscience & nanotechnology Condensed Matter Physics Gibbs free energy chemistry Mechanics of Materials Ceramics and Composites symbols Hydroxide 0210 nano-technology |
| Zdroj: | Powder Metallurgy and Metal Ceramics. 56:697-706 |
| ISSN: | 1573-9066 1068-1302 |
| Popis: | Lanthanum hafnate La2Hf2O7 was produced chemically by inverse precipitation from ammonia solution and a mixture of La and Hf nitrates, followed by hydroxide decomposition at 1250°C in air and melting of the oxide mixture in a solar furnace. The formation of La2Hf2O7 was ascertained by X-ray diffraction. The La2Hf2O7 enthalpy increment was measured in the range 490–2120 K (for the first time in the temperature ranges 490–988 K and 1740–2120 K) by drop calorimetry using a Setaram HT-1500 high-temperature differential calorimeter and a high-temperature calorimetric device. A fitted equation for the enthalpy increment was used to calculate the main thermodynamic functions (heat capacity, entropy, and Gibbs energy) in the temperature range 298–2120 K. The experimental results are compared with the published data and those assessed using the Neumann–Kopp rule. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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