Superior La0.67K0.33-xSrxMnO3 films with room-temperature TCR prepared by spin coating method

La0.67K0.33-xSrxMnO3 thin films were grown on LaAlO3 (010) substrates via sol-gel and spin coating methods. The replacement of K ions with Sr ions affected the eg electron bandwidth and concentration of Mn3+/Mn4+ pairs as well as effectively modulated the magnetic/orbital order and lattice structure. Consequently, the ferromagnetic metal to paramagnetic insulation transition was affected, which further optimized the resistivity, temperature coefficient of resistivity (TCR), peak TCR temperature (TK), and peak resistivity temperature (TP). At temperatures below 230 K, temperature-independent scattering and electron-electron scattering were practically not observed in the films. Overall, electrical properties of films improved with an increase in the Sr doping content. The superior La0.67K0.27Sr0.06MnO3 film exhibited a maximum TCR of 11.88% K-1 (298.3 K), which is approximately 31% higher than that of bulk ceramic with the same composition. The as-developed films exhibit significant potential for application in uncooled infrared bolometers.