Thermal expansion behaviour and phase stability of AFe2As2 (A = Ca, Sr and Eu) using powder diffraction technique
| Autor: | Sanjay Kumar Mishra, Ranjan Mittal, P. S. R. Krishna, S. L. Chaplot, S. Matsuishi, P. D. Babu, Hideo Hosono, P. U. M. Sastry |
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| Rok vydání: | 2016 |
| Předmět: |
Materials science
Analytical chemistry General Physics and Astronomy 02 engineering and technology Atmospheric temperature range 021001 nanoscience & nanotechnology 01 natural sciences Thermal expansion Tetragonal crystal system Lattice constant Phase (matter) 0103 physical sciences X-ray crystallography 010306 general physics 0210 nano-technology Anisotropy Powder diffraction |
| Zdroj: | Pramana. 86:1369-1381 |
| ISSN: | 0973-7111 0304-4289 |
| DOI: | 10.1007/s12043-016-1201-2 |
| Popis: | The thermal expansibilities and phase stabilities of AFe 2As 2 (A = Ca, Sr and Eu) have been investigated by powder diffraction techniques in the temperature range 5–600 K. We found the anisotropic thermal expansivities with temperature for all the compounds. The lattice parameter in the tetragonal phase ( A T) of CaFe 2As 2 contracts with increasing temperature, whereas C T expands. The rate of contraction in A T is lower than the rate of expansion in C T. Other compounds show normal thermal expansion behaviour along both a- and c-axes. In-plane expansion (i.e., along the a-axis) is found to be the smallest for EuFe 2As 2 and the highest for BaFe 2As 2. However, the rate of change of thermal expansivities along out-of-plane (i.e., along the c-axis) is higher as we go from Ba, Sr, Eu and Ca, respectively. Above 600 K, we notice the appearance /disappearance of certain reflections which suggest that tetragonal phase is not stable above this temperature for these compounds. |
| Databáze: | OpenAIRE |
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