Effect of Fe substitution on temperature coefficient of resistance and magnetoresistance of La0.67Ca0.33MnO3 polycrystalline ceramics

Abstract

La0.67Ca0.33MnO3 perovskite manganate exhibits high temperature coefficient of resistance (TCR) and large magnetoresistance (MR) effect, these enable novel multifunctionalities. Mn site substitution can change magnetic order of the manganates, thereby tailoring both electrical and magnetic transport. Herein, La0.67Ca0.33Mn1-xFexO3(0 ≤ x ≤ 0.06) polycrystalline ceramics were prepared by sol-gel route. The effect of Fe substitution on TCR and MR of La0.67Ca0.33MnO3 was studied. Fe replacing Mn ions, would weaken double exchange, and significantly reduced Curie temperature and ferromagnetism. Additionally, Fe doping promoted the development of grain. TCR increased first with Fe content x and then decreased, and reached 45.2%·K-1 at x = 0.01, which is the highest value reported. Notably, with Fe doping, MR gradually increased and reached 81.1% (1 T) at x = 0.06. Fe doping can significantly enhance TCR and MR, which generates promising potential in (uncooled) thermistor/infrared detecting and magnetic sensors.