Influence of silver addition on microstructures and transport properties of La0.67Ca0.33MnO3:Ag x composites

Abstract

In order to obtain high temperature coefficient of resistance (TCR) value of La0.67Ca0.33MnO3:Ag x (LCMO:Ag x ) composites, samples with different Ag contents (x = 0, 0.1, 0.2, 0.25, 0.3, and 0.5) were prepared by sol–gel method. X-ray diffraction analyses indicated that all samples had orthorhombic perovskite structures. As x increased, lattice parameters (a, b, c) and cell volumes underwent slight expansions. Interestingly, the addition of Ag dramatically affected TCR and magneto-resistance (MR) values. Elevated TCR value up to 53.46%·K−1 at 277 K was observed for LCMO:Ag x composites with added Ag at the composition of x = 0.1. Meanwhile, MR value at 263 K reached 71% at the magnetic field of 1 T for samples with Ag composition of x = 0.25. The increase in Mn4+/Mn3+ ratio and improvement in crystallization caused by added Ag was found responsible for the elevated values of TCR, MR, and Tp. These findings may have practical use in high-performance magneto-resistive manganites.