Effect of A-site cation substitution on magnetic transition temperature of(LaCa) MnO3

The ferromagnetic transition temperatures have been measured an two bathes of perovskite manganese oxides such as (La1-xRx)(2/3) Ca-1/3 MnO3 (R = Ce, PT, Nd, etc.) and La-2/3 (Ca1-yCdy) (1/3) MnO3. It is found that the (La1-x Rx) (2/3) Ca-1/3 MnO3 samples have obviously different Curie temperature T- C although their (r(A)) (the average A-site cation radius) are almost ident ical, and the T-C in the system of(La1-xRx) (2/3) Ca-1/3 MnO3 compounds inc reases with increasing y although (r(A)) decreases slightly. It is suggeste d that the Curie temperature should be influenced by the average local A-si te magnetic moment in the ferromagnetic perovskite manganite system.