A comparative study on high TCR and MR of La0.67Ca0.33MnO3 polycrystalline ceramics prepared by solid-state and sol-gel methods

Abstract In this work, La0.67Ca0.33MnO3 (LCMO) polycrystalline ceramics were fabricated by solid-state (SS) and sol-gel (SG) methods. Morphologies, crystal structures, element compositions, and contents of as-obtained LCMO ceramics were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and X-ray photoemission spectroscopy (XPS). Compared to the SG ceramic, specimens fabricated by SS showed numerous smaller grain size particles and scattered grain boundaries (GBs), leading to higher resistivity. Values of the peak temperature coefficient of resistivity (TCR) of both LCMO ceramics prepared by SS and SG were recorded as 14.12 % at 261.73 K and 31.96 % at 260.64 K, respectively. Respective magnetic resistance (MR) values were estimated to 29.97 % at 264.78 K and 54.27 % at 263.80 K, respectively. Also, SG sample displayed LCMO polycrystalline with better crystal quality, as well as improved electrical and magnetic properties. Hence, SG method was more suitable for preparation and application of LCMO ceramics, especially for use in highly sensitive infrared detectors and magnetic sensors.