Optimized TCR and MR properties of La0.7-xSmxCa0.3MnO3 ceramics by Sm3+ doping

Abstract

La0.7Ca0.3MnO3 (LCMO), with its high temperature coefficient of resistance (TCR) and large magnetoresistance (MR) effect, has emerged as a leading material in the field of new multi-functional ceramics. Enhancing the magnetoresistive effect of LCMO in low magnetic field and expanding its application range is one of the main research goals of this kind of materials. In this work, La0.7-xSmxCa0.3MnO3 (LSCMO) (0≤x≤0.09) ceramic targets with different doping amounts were successfully prepared by sol-gel method, and the influence mechanism of Sm3+ doping on the magnetoresistive effect and electrical transport performance of LSCMO was systematically analyzed. X-ray diffraction (XRD) results showed that the lattice parameters (a,b,c,V) of LSCMO decreased slightly, indicating that the doping amount of Sm3+ at the A-site increased. Scanning electron microscopy (SEM) showed that the grains were closely connected without obvious pores, the grain size decreased slightly. The ρ-T curve shows an obvious metal-insulator (M-I) transition, with the increase of Sm3+, the increase of resistivity, metal-insulator transition temperature (TMI) and ferromagnetic-paramagnetic (FM-PM) transition temperature (TC) move towards low temperature. When x=0.015, the peak value of TCR reaches 41.94%·K-1, and when x= 0.06, the peak value of MR reaches 80.25%, both TCR and MR are improved. The results show that: Sm3+ doping can effectively enhance the electromagnetic transport performance of LSCMO. This material has a very wide application prospect in the fields of magnetic storage, and infrared detection.