Effect of TiO2 addition on the structural and electrical properties of La0.67Ca0.33MnO3

Numerous studies have been conducted on perovskite manganites to enhance the low field magnetoresistance (LFMR). One effective approach is adding an insulating oxide as the artificial boundary layer outside the manganite grain. This research aims to determine the structural and electrical properties of La0.67Ca0.33MnO3 (LCMO) when added with different contents of TiO2. LCMO powder was prepared via sol–gel route before appended with TiO2 nanoparticle to form (1 − x) LCMO: x TiO2, x  = 0.00, 0.005, 0.010, 0.030 and 0.050. The structural analysis by X-ray diffraction (XRD) revealed no significant changes in the lattice parameter, crystallite size, bond length and angle as the concentration of TiO2 increased. The TiO2 in LCMO caused an increase in resistivity and a decrease in metal–insulator transition (TMI). This indicates the double exchange (DE) has been suppressed by the TiO2 addition, which acts as disordered layers at LCMO grains surface. The electrical resistivity of the samples was fitted with theoretical models, and the conduction mechanism is explained by the grain/domain boundary effect and the small polaron hopping (SPH) model. The first fitting inferred that the grain/ domain boundary effect plays an inevitable role throughout the conduction in the metallic region. The latter supports the notion that the presence of TiO2 in the LCMO compound produces a more resistive grain boundary.