Role of gallium ion on the conducting properties of La0.7(Ba, Sr)0.3Mn1−xGaxO3 (x=0.0, 0.1 and 0.2) perovskite

Abstract The transport properties of Ga-doped La 0.7 (Ba, Sr) 0.3 Mn 1− x Ga x O 3 ( x =0.0, 0.1 and 0.2) perovskite materials were investigated by admittance spectroscopy over a wide range of temperatures and frequencies. The electronic conduction was found to be dominated by thermally activated hopping and to depend strongly on Ga-content. Results have shown samples with x =0.0 and 0.1 exhibit a metallic behavior at low temperature and a semiconducting one at high temperature. The temperature ( T MI ) of the metal–insulator transition was found to be about 180 and 120 K for samples with x =0.0 and 0.1, respectively. Ga doping leads to a depletion in the number of hopping electrons, which suppresses metallicity and pushes the system in semiconductor side. Besides, the activation energy ( E a ) deduced from the variation of conductance as a function of temperature, was found to increase from 89 to 165 meV when x increased from 0.0 to 0.2. This increase can be explained by the decrease of charge carriers with increasing Ga-content.