| Autor: |
Cheikhrouhou, A., Sellami-Jmal, E., Marzouki, A., Cheikhrouhou-Koubaa, W., Njah, N. |
| Předmět: |
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| Zdroj: |
Journal of Superconductivity & Novel Magnetism; Mar2015, Vol. 28 Issue 3, p831-838, 8p |
| Abstrakt: |
Magnetic and magnetocaloric properties of La□CaMnO (≤ x ≤ 0.15) perovskite manganites were investigated. Our polycrystalline samples were elaborated using sol-gel method. The Rietveld refinement shows that all our samples are single phase and crystallize in the orthorhombic structure with Pbnm space group. Lanthanum deficiency leads to a decrease of the unit cell volume. The surface morphology was carried out using scanning electron microscopy (SEM). Magnetization measurements versus temperature in a magnetic applied field of 50 mT showed that all our deficient samples exhibit a paramagnetic-ferromagnetic transition with decreasing temperature. With increasing lanthanum deficiency, the Curie temperature T decreases from 275 K for x = 0 to 257 K and for x = 0.15. A large magnetic entropy change |Δ S|, deduced from isothermal magnetization curves, has been observed in our samples with a peak centred around their respective transition temperature. The maximum of the magnetic entropy change $ \vert {\Delta } S_{M}^{\text {Max}}\vert $ under a magnetic field change of 5 T is found to decrease from 5.11 J/kg/ K for x = 0 to 3.98 J/kg K and for x = 0.15. The relative cooling power decreases from 237.5J/kg for x = 0 to 217.4 J/kg and for x = 0.15. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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