La空位掺杂对La-Ca-Sr-MnO_3磁热性质的影响

Effect of Vacancies Addition on the Magnetocaloric Properties for La_(0.7-x)Ca_(0.28)Sr_(0.02)MnO_3

用溶胶-凝胶法制备了不同空位掺杂的系列样品La_(0.7-x)Ca_(0.28)Sr_(0.02)MnO_3,研究了La^(3+)空位浓度对样品居里温度和磁热效应的影响。结果表明,在La位掺入少量空位(x<0.06),可以实现将样品的居里温度有效调整至室温,同时也促进了样品磁熵变的提高。当La空位掺杂x=0.06时,与未空位掺杂样品相比,居里温度由227 K提高到264 K,近室温,其磁熵变值为3.01 J·kg-1·K-1(外加磁场1 T)。该系列样品在室温附近,较低磁场下,有较强的磁制冷能力。

Polycrystalline samples of La0.7-xCa0.28Sr0.02MnO3 with different vacancies were prepared by the sol-gel technique, and the effects of the concentration of vacancies in La3 ＋ - site on the Curie temperature and magnetocaloric properties were investiga- ted. The results show that the Curie temperature of the sample can be adjusted to room temperature effectively, while the magnet- ic entropy changes of the sample can be increased by La vacancies（x 〈0.06）. When the La vacancy is doped with x =0. 06, the Curie temperature rises from 227 K to 264 K, approximate to room temperature, and the magnetic entropy change is 3.01 J · kg-1 · K - 1 （1T）. The magnetic refrigeration capacity is strong when the samples are near room temperature and in low mag- netic field.