Correlation of microstructure and electrical conduction behaviour with defect structure of niobium doped barium stannate

Microstructure and electrical conduction behaviour in the system BaSn1−xNbxO3 (x ≤ 0.10) have been correlated with the defect structure. In the SEM micrographs, average grain size of the samples with composition x ≤ 0.010 was found to be about 3 μm whereas the average grain size of the samples with compositions x ≥ 0.050 was found to be much less than 1 μm. Similar trend of variation in the diffraction domain sizes or crystallite size is observed from powder X-ray diffraction data. It has been reported earlier that charge compensation mechanism in this system changes from electronic for x ≤ 0.01 to ionic for x = 0.050 and 0.100. This results a change in the nature of conduction from n- to p-type in going from x = 0.010 to 0.050.