Effect of TiO₂ Nanoparticle on the Structural and Electrical Properties of Nd0.67Sr0.33MnO₃ /TiO₂ Composites

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In this work, (1-x) (Nd 0.67 Sr 0.33 MnO 3 ): x (TiO 2 ) composites with x = 0, 0.1, 0.2, 0.3 and 0.4 have been prepared to investigate the structural and electrical properties. Nd 0.67 Sr 0.33 MnO 3 (NSMO) was synthesised via the solid-state reaction method before incorporated with TiO 2 . The addition of TiO 2 nanoparticle as the secondary phase in manganite composite would favour the spin-polarized tunnelling near to the grain boundary and thus enhance the extrinsic magnetoresistance. Nevertheless, nanoparticle addition might contribute to substitution and diffusion with manganite compound as reported in literature. The effect of the TiO 2 nanoparticle addition into NSMO composites has been examined by an X-ray diffractometer (XRD) and a four-point probe (4PP) system. From the thermogravimetric analysis (TGA), NSMO phase formation occurred in between 756.45 - 977.59 °C. XRD patterns showed that there is no peak shift when the TiO 2 concentration increases. It can be deduced that TiO 2 was segregated at the NSMO grain boundary region and its grain surface. However, a small amount of Ti atoms are expected to replace the Mn atoms in NSMO crystal system and has caused the increase in crystallite size. The electrical study showed that the presence of TiO 2 nanoparticle and substitution of Ti in Mn sites have weaken the double exchange (DE) mechanism and suppressed the metal-insulator transition temperature (T MI ). In addition, the insulating behaviour of TiO 2 has also caused the resistivity of composites to increase drastically.