Effects of Ag doping on the electrical properties of La2/3A1/3MnO3(A=Ca, Sr, Ba) composites materials

La(2/3)A(1/3)MnO(3):Ag-x(A=Ca, Sr, Ba, LAMO:Ag-x, x=0, 0.1, 0.2, 0.3, 0.4, mol%) composites materials were prepared successfully by co-precipitation route. XRD results showed that the pure phase LAMO:Ag-x samples were obtained. By substitution of A site with Ag ion, the crystal lattice and cell volume were expanded slightly for LCaMO: Ag-x and LSrMO:Ag-x, but shrinked slightly for LBaMO:Ag-x R-T measurement results showed that the maximum temperature coefficient of resistance (TCR) of LCaMO:Ag-x composites reached 28%/K as x=0.4, T-k=271.3 K (T-k: temperature at the maximum TCR value). SEM images showed that for LCaMO composites, the particle size were enlarged. The uniform, homogeneity and crystal quality were improved with increase of Ag doping. The TCR enhancement of LAMO:Ag-x composites are discussed by the microscopic mechanism with Ag doping.