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) we re synthesized using a sol-gel technique. Structure analysis, morphology ob servation and magnetic measurement have been used to study the effect of va cuum concentration of La3+ on the Curie temperature and magnetic entropy ch ange of La0.8-xCa0.2MnO3. The experimental results show that by tuning the vacuum concentration of La3+, the materials could exhibit very different Cu rie temperatures (from 180 to 260K). All the samples in this paper have lar ge magnetic entropy change, especially for La0.77Ca0.2MnO3 sintered at 1100 degreesC, which has a very large magnetic entropy change DeltaS(M)=3.76J/k g.K under the magnetic field H=1.0T. The phenomenon of large magnetic entro py change, high Curie temperature, high electrical resistivity and high che mical stability make this material a suitable candidates for refrigerants a t high temperature.