Structural magnetic and electrical properties of La0.6Ba0.4-xSrxMnO3 perovskite

We have studied the structure and magnetic transition with respect to the a verage size of the A site cations (r(A)) in the solid solution La0.6Ba0.4-x SrxMnO3 (0 less than or equal to x less than or equal to 0.4). In this solu tion, the ratio Mn3+/Mn4+ is fixed at 1.5. X-ray diffraction patterns show a phase transition from cubic to rhombohedral for 0.1 less than or equal to x less than or equal to 0.15. The variation of the Curie temperature T-C i s explained by the sharp increase of the mismatch effect sigma(2) with incr easing (r(A)), which reflects the great discrepancy between La3+ and Ba2+ s izes. At low temperature, the spin-disorder scattering process has an impor tant role in the resistivity. The structural and magnetic properties are co rrelated with the change of Mn-O-Mn bond angle.