Co-optimization of Ag and K doping to regulate room-temperature coefficient of resistivity of La0.7Ag0.3-xKxMnO3 films

Abstract

In this study, La0.7Ag0.3-xKxMnO3 (LAKMO, x = 0.15, 0.16, 0.17, 0.18, and 0.19) films with excellent electrical properties and low surface roughness were prepared on SrTiO3 (001) substrates using the spin-coating method. The crystal structures and ion valence states of the LAKMO films were modified by adjusting the doping amounts of Ag and K. The Jahn–Teller effect and electron–lattice coupling were enhanced with the MnO6 octahedron undergoes distortion. Moreover, the double-exchange interaction was improved with an increase in the number of Mn4+/Mn3+ ion pairs. Under the influence of these factors, the electrical transport properties especially the temperature coefficient of resistivity (TCR) of the LAKMO films can be refined modulated or optimized via A-site Ag and K co-doping. When x = 0.17, the maximum TCR of LAKMO reached 11.23 % K−1 at 293.23 K. Thus, La0.7Ag0.13K0.17MnO3 film with a large TCR exhibited excellent thermal properties at room temperature and was considered material for application to uncooled infrared bolometers.