Thermal diffusivity of La_1-XCa_XMnO₃ up to 1200 K

The thermal diffusivity α(T) and the normalized specific heat C(T)/C(300 K) of the colossal magnetoresistive manganite, La_1-XCa_XMnO₃ (LCMO; 0≤X≤1.0), were measured in the temperature range from 10 to 1200 K. At high temperatures above 300 K, the temperature differential of the diffusivity, dα/dT, changes from negative to positive with increasing Ca concentration X. The positive dα/dT coefficient is not standard and a possible origin correlated with the local distortion around the Jahn-Teller active Mn³⁺ ions is proposed. The phase diagram of the LCMO system is completed up to 1200 K using the anomalies of α(T), C(T) and other physical quantities.