Influence of Bi3+ doping on electronic transport properties of La0.5−xBixCa0.5MnO3 manganites

Electronic transport properties of La0.5−xBixCa0.5MnO3 (x=0, 1/16, 1/8, 1/4, 3/8 and 1/2) compounds have been studied systematically to investigate their charge ordering (CO) behaviors. The results show that the CO temperature increases with the substitution of Bi3+ ion for La3+ ion, suggesting that the charge ordering is enhanced. This is attributed to the special role of the 6s2 lone pair of Bi3+. It is found that for all the samples the adiabatic small polaronic conduction mechanism is responsible for the transport behavior above CO transition, whereas Mott's variable range hopping mechanism dominates below the CO transition. In addition, the electronic transport behavior of La0.5−xBixCa0.5MnO3 compounds is high sensitive to an external magnetic field, which could raise fresh opportunities for application in magnetic sensors.