Phase diagram of (La0.25Pr0.75)0.7Ca0.3MnO3 with 18O isotope

Abstract The effect of partial oxygen isotope substitution 16 O– 18 O in (La 0.25 Pr 0.75 ) 0.7 Ca 0.3 MnO 3 ceramics was investigated. The temperature profiles of the ferromagnetic phase in the samples with different concentration p of 18 O have were reconstructed from thermal conductivity data employing the general effective medium equations. It was found that ferromagnetic transition temperature and temperature of metal–insulator percolation transition decrease linearly with increasing concentration of 18 O. The isotopic shift of charge ordering transition appears to be very small. As a result, the phase diagram in the T – p plane was obtained and the origin of the large isotope effect was discussed.