CURIE TEMPERATURE AND MAGNETOCALORIC EFFECT OF POLYCRYSTALLINE La0.8-xCa0.2MnO3

Polycrystalline samples of La0.8-xCa0.2MnO3(x=0,0.01,0.03,0.05,0.08,0.1) were synthesized using a sol-gel technique. Structure analysis, morphology observation and magnetic measurement have been used to study the effect of vacuum concentration of La3+ on the Curie temperature and magnetic entropy change of La0.8-xCa0.2MnO3. The experimental results show that by tuning the vacuum concentration of La\+\{3+\}, the materials could exhibit very different Curie temperatures (from 180 to 260K). All the samples in this paper have large magnetic entropy change, especially for La0.77Ca0.2MnO3 sintered at 1100℃, which has a very large magnetic entropy change ΔSM=3.76J/kg·K under the magnetic field H=1.0T. The phenomenon of large magnetic entropy change, high Curie temperature, high electrical resistivity and high chemical stability make this material a suitable candidates for refrigerants at high temperature.