Charge ordering temperatures of Bi1-xSrxMnO 12 (0.45 ≤ x ≤ 0.8)

We have investigated the charge ordering phenomenon from the temperature dependence of inverse susceptibility, resistivity, and thermoelectric power (TEP) for Bi_1-xSr_xMnO₃ (BSMO) from 300 K to 700 K. At high temperatures, susceptibility follows Curie-Weiss law. The resistivity data indicate insulating behavior of BSMO. TEP (S(T)) value is negative and weakly temperature-dependent in the high temperature regime. The slope of TEP changes dramatically near the charge ordering temperature (T _CO, indicating an increase of energy gap due to the charge ordering. In the vicinity of T_CO thermal hysteresis is observed in TEP data as well as in the resistivity data, which is consistent with the nature of the martensitic transition of the charge ordering phenomena. From this hysteretic behavior, we estimated T_CO- As Sr concentration increases, T _CO shifts to lower temperature from T_CO ∼ 490 K for x = 0.45 to T _CO ∼ 435 K for x = 0.8, and the thermal hysteretic behavior becomes less pronounced. The electrical transport properties have been discussed in terms of carrier localization due to charge ordering transition accompanied by the local lattice distortions.