A-site K-doping to enhance room-temperature TCR of polycrystalline La0.8Sr0.2-xKxMnO3 ceramics

• Published in: Journal of alloys and compounds 2020-12, Vol.847, p.1, Article 156417
• Main Authors: Li, Hongjiang, Chu, Kaili, Pu, Xingrui, Zhang, Shuai, Dong, Gang, Liu, Yang, Liu, Xiang
• Format: Article
• Language: English
• Subjects: Bolometers; Ceramics; Doping; Double exchange (DE) mechanism; Electrical resistivity; Jahn-Teller (JT) effects; Jahn-Teller effect; Polycrystalline La0.8Sr0.2-xKxMnO3 (LSKMO) ceramics; Polycrystals; Room temperature; Sensitivity enhancement; Sol-gel processes; Temperature; Temperature coefficient of resistivity (TCR); Transport properties
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.156417

Herein, polycrystalline La0.8Sr0.2-xKxMnO3 (LSKMO, 0 ≤ x ≤ 0.2) ceramics with varying K concentration are successfully synthesized via a facile sol-gel method. The electrical transport properties and microstructural of the prepared samples are characterized and analyzed in detail. The different characterization results show that K+ ion substituted La3+ and Sr2+ ions significantly influenced the double exchange (DE) mechanism and Jahn-Teller (JT) effects. The electrical resistivity studies suggest that as the K doping content rose, the resistivity increased and peak resistance temperature decreased. Electrical transport properties of samples are analyzed via the combination of DE mechanism, JT effects, variable-range hopping and small-polaron hopping model. The temperature coefficient of resistance (TCR) measurement demonstrates the enhanced temperature sensitivity for the K-doped polycrystalline ceramics samples as compared to the pure La0.8Sr0.2MnO3 samples. The optimized x content for the polycrystalline LSKMO ceramics is determined to be x = 0.08. At this x value, the peak TCR of the resistivity measured 9.11% K−1 at 292.44 K. These results confirm that high room-temperature TCR values can be achieved by optimizing A-site K doping and demonstrate the potential of polycrystalline La0.8Sr0.12K0.08MnO3 ceramic in room-temperature infrared bolometers. •TCR of La0.8Sr0.12K0.08MnO3 ceramic showed a higher value of 9.11% K−1 at 292.44 K.•Electrical properties were analyzed via DE mechanism, JT effects, VRH and SPH model.•Combination of Raman, FTIR, and XRD confirmed that a distortion of the MnO6 octahedron.•XPS identified the oxygen deficiency will effects the variation of Mn3+/Mn4+ pairs.•La0.8Sr0.12K0.08MnO3 ceramic could be useful for application in infrared bolometers.