Impact of La3+ doping on temperature coefficient of resistivity and peak temperature of La x Ca0.89-xSr0.11MnO3 films prepared by sol-gel spin coating method

Herein, refined La x Ca 0.89- x Sr 0.11 MnO 3 (LCSMO, x  = 0.65, 0.68, 0.71 and 0.74) films were prepared through the sol-gel spin-coating. The influence of La 3+ content on the structural properties of LCSMO films was investigated by X-ray diffraction and Atomic force microscope, demonstrating that LCSMO films can grow well on SrTiO 3 (00 l ) substrate. Besides, X-ray photoemission spectroscopy verified the double exchange (DE) effect was weakened with La 3+ dopant. The La 3+ doping and interconnected grains boundaries (GBs) led to the weakening DE effect and GBs scattering, respectively. Due to superior GBs connectivity, the resistivity of LCSMO films was less than 7.1 × 10 −4 Ω·cm at low temperature of 100 K. Importantly, it is an effective control method to keep the temperature ( T k ) corresponding to temperature coefficient of resistivity ( TCR ) at room temperature with Sr 2+ content as constant in LCSMO films. At x  = 0.71, the peak TCR value was found to be 8.84%/K and corresponding T k was 283.15 K. These results are beneficial for advanced application of uncooling infrared bolometer.