Microstructure, Magnetic and Electrical Transport Properties of Sol-Gel Synthesized La_0.7Sr_0.2Ca_0.1MnO₃:TiO₂ Composite

Abstract

Electrical transport in materials have been studied extensively due to its great potential in spintronic technology. The introduction of the secondary phase into the manganite matrix can modify the electrical properties, subsequently improving the low-field magnetic resistance (LFMR). In this work, we study the change in electrical properties at different temperatures of polycrystalline (1-x)La0.7Sr0.2Ca0.1MnO3/xTiO2 (LT) composites where x = 0, 0.05 and 0.1. Polycrystalline La0.7Sr0.2Ca0.1MnO3 (LSCMO) was synthesized by sol-gel method, calcined at 700 °C, and pre-sintered at 800 °C for 6 h before adding TiO2. TiO2 as filler was mixed with LSCMO by wet mixing and stirring for about 30 min until a homogeneous compound was formed. Composite LT was then inserted to oven up to 100 °C for 2h to remove the moisture, compacted at 10 MPa, and sintered at 1200°C for 12 h. All samples in the LSCMO phase have a rhombohedral crystal structure with space group R3c. The crystal structure parameters were studied using Rietveld refinement through GSAS II software. The sample was characterized by SEM to represent the morphology of the sample. As the TiO2 content increased, the magnetization decreased, as observed by VSM analysis at room temperature. The electrical transport properties of pure LSCMO and LT were characterized by cryogenic from 195K to 260 K. The resistivity of LT10 is too high compared to that of LT5 and as the temperature increases, the resistivity in this range will decrease. For 200 K, the resistivity of LSCMO, LT5 and LT10 are 3.09 x 10-2 ohm.cm, 4.40 x 103 ohm.cm and 4.77 x 104 ohm.cm respectively.