High temperature coefficient of resistivity (TCR) of Nd0.67Sr0.33MnO3 films by optimizing sintering temperature

In this study, Nd 0.67 Sr 0.33 MnO 3 (NSMO) films are deposited on La 0.3 Sr 0.7 Al 0.65 Ta 0.35 O 3 (LSAT) substrates using sol–gel spin coating method and sintered at different temperatures ( T s  = 1250, 1300, 1350, 1400 and 1450 °C). Consolidated analysis of their crystal structure, surface morphology and valence states enables one to conclude that increased T s facilitates grain growth and enhances crystallinity of films. Moreover, enhancing T s from 1250 to 1350 °C leads to a decrease in Mn-O bond length ( d (Mn-O) ) and an increase in Mn-O-Mn bond angle ( θ (Mn-O-Mn) ). In the XPS analysis, the Mn 4+ and O 2– content kept increasing with the rise of T s . When Mn 4+ concentration ≤ 33%, the double exchange (DE) interactions was undoubtedly facilitated, which was beneficial for the electrical properties of the NSMO films. These changes eventually result in large temperature coefficient of resistivity ( TCR ). According to these results, Nd 0.67 Sr 0.33 MnO 3 film, with a maximum TCR value of 21.85% K −1 at T s  = 1350 °C, are promising materials for the manufacturing of sensitivity switches and infrared bolometers.