Enhanced TCR and MR by grain boundary modification and phase competition in La0.67Ca0.33MnO3: Aux (x=0, 0.05, 0.1, 0.15) composite ceramics

La 0.67 Ca 0.33 MnO 3 (LCMO) ceramics exhibit high temperature coefficient of resistance (TCR) and colossal magnetoresistance effect (CMR). Increasing their TCR and MR values can enhance potential applications in uncooled infrared detectors and magnetic storage devices. However, presence of inherent grain boundaries and defects within these ceramics significantly limits their performance. Therefore, this work proposed modifying grain boundaries of LCMO ceramic using low-resistivity and stable Au to enhance its electrical transport and improve magnetoresistance performance through competition between antiferromagnetic Au and ferromagnetic La 0.67 Ca 0.33 MnO 3 . A series of La 0.67 Ca 0.33 MnO 3 : Au x ( x  = 0, 0.05, 0.10, 0.15) composite ceramics was prepared by sol-gel and solid-state methods. Introduction of Au increased TCR from 40.1 %·K −1 to 55.2 %·K −1 and MR from 60.4 % to 74.2 %, when x  = 0.10. This study demonstrates that proposed strategy involving multiphase interactions can significantly improve electrical transport and magnetic properties of functional materials , with promising applications in areas such as thermoelectric and magnetoelectric conversion.