Effect of Ho-doping on structural, electrical and magnetic properties of La0.7Sr0.3MnO3 ceramics prepared by Plasma-Activated Sintering

Different components of La0.7−x Ho x Sr0.3MnO3 (LHSMO, x = 0, 0.1, 0.2, 0.3) ceramics were fabricated by Plasma-Activated Sintering (PAS), so as to study the correlation between the contents of Ho3+ and the structural, electrical, magnetic properties. XRD and SEM confirmed that LHSMO ceramics prepared by PAS exhibited high-purity phase and dense microstructure. The measurement of electrical resistivity showed that the resistivity of LHSMO ceramics increased, and the metal–insulator transition temperature decreased with the increasing Ho-doping content. The resistivity data were then fitted using various empirical equations, and the conduction mechanism of LHSMO ceramics was found to be in accord with the electron–magnon scattering process in the low-temperature region and the small polaron hopping model in the high-temperature region. Lastly, we calculated the values of magnetoresistance of the LHSMO ceramics, which increased with increasing Ho-doping content, from 3.5% for x = 0 to 14.6% for x = 0.3. Therefore, the doping of Ho3+ into La0.7Sr0.3MnO3 can effectively enhance the low-field magnetoresistance effect.