Enhanced Electrical Properties of La0.7(Ca0.2Sr0.1) MnO Polycrystalline Composites with Ag Addition

La(CaSr)MnO:Ag(LCSMO:Ag, x = 0, 0.1, 0.2 and 0.3, mol%) polycrystalline composites were prepared by a solid-state reaction method. With the increasing of Ag addition, the temperature coefficient of resistance (TCR) and the metal-to-insulator transition temperature () reach the maximum values of 9.1 % K and 258 K for LCSMO:Ag (x = 0.3) sample, which can be used as a candidate of bolometer or infrared detectors. The improvement of Mn concentration and grain connectivity by Ag addition is responsible for the enhancement of and TCR values. The fitting curves of electrical resistivity show that the low temperature region () is fitted with grain/domain boundary, electron-electron, and magnon scattering mechanisms, as well as the high temperature region () is fitted with adiabatic small-polaron hopping mechanism.