A mechanical investigation on the phase transition behavior of La0.7Ca0.3MnO3-delta ceramics

The characteristics of the phase transition of polycrystalline La0.70Ca0.30 MnO3-delta (LCMO) was investigated by using the vibrating reed method. The internal friction (Q(-1)) of the sample shows two peaks: P-1 and P-2. The f irst internal friction peak, P-1, appears in heating up and cooling down in dicative of a paramagnetic to ferromagnetic phase transition with a conside rable resonant frequency drop at the transition point. The second broader i nternal friction peak, P-2, appears only in heating up and its correspondin g frequency (f) exibits a maximum. Additionally, the P-1 temperature was fo und to be linked with a thermal absorption peak and a variation of the magn etization and the electric resistance.