Low-Field Magnetoresistance of La0.78Ba0.22MnO3:WO3 Composites

We have studied the effect of making composite a perovskite manganite with semiconductor WO3 to improve magnetoresistance under low fields. The X-ray diffraction spectra of LBMO-WO3 composites with different molar ratios show secondary peaks which are located next to the main peaks of LBMO manganite, which is related to the BaWO4 phase. In other words, tungsten trioxide has reacted with Ba atoms in manganite and formed the secondary phase of BaWO4, altering the spatial group and increasing the volume of composite unit cell compared to the pure manganite sample. The presence of this compound weakens the double exchange between LBMO grains. So that by increasing the amount of WO3 composite to manganite, the Curie temperature decreases gradually. Also, with the presence of BaWO4 insulating material among manganite grains, electron tunneling is weakened among LBMO grains and electrical resistance increases.

Automated summary

By studying the composite of perovskite manganite with semiconductor WO3, it was found that a secondary phase BaWO4 is formed, altering the structure and increasing the volume of the composite unit cell. This weakened the double exchange effect between manganite grains and increased electrical resistance due to weakened electron tunneling among the grains.