High Room-temperature TCR of La0.7(K0.25Sr0.05)MnO3:xAg2O Composites Obtained at Optimized Ag2O Ratio

Abstract In this study, La0.7(K0.25Sr0.05)MnO3 (LKSMO) perovskites were prepared by the sol-gel method in the presence of different added Ag2O ratios to yield LKSMO:xAg2O composites. The structures of LKSMO:xAg2O were studied by X-ray diffraction (XRD), Raman, and Fourier transform infrared (FTIR) spectroscopy. The surface morphologies were characterized by scanning electron microscopy (SEM), elemental mapping, and energy dispersive spectrometry (EDS). The changes in the concentrations of Mn3+ and Mn4+ ions were examined by X-ray photoelectron spectroscopy (XPS). The results indicated that the addition of Ag2O led to the formation of a second phase (Ag) within the composites, occupying the A-site in LKSMO matrix by Ag+ ions. This structural change altered the magnetic and electric properties of LKSMO:xAg2O samples. The LKSMO:0.3Ag2O composite displayed the largest TCR and higher MR at room temperature compared to published literature. In sum, the magnetic and electric properties of LKSMO:xAg2O samples can be optimized by varying the amount of added Ag2O.