Synthesis, structure and electrical behaviour of nickel-doped barium stannate

Abstract

The possibility of formation of a solid solution in the system BaSn 1− x Ni x O 3 has been explored up to x ≤ 0.20. It has been confirmed that single phase solid solution forms up to x ≤ 0.10. Dielectric and ac conductivity of the samples have been studied in the temperature range 350–650 K and frequency range 10 Hz–2 MHz and dc conductivity of the samples have been measured in the temperature range 550–1100 K. Seebeck coefficient ‘ α’ of the samples have been measured in the temperature range 350–650 K. Negative value of ‘ α’ in the entire range of temperature measurement shows that conducting species are negatively charged. On the basis of value of activation energy for dc conduction and sign of Seebeck coefficient, conduction in the low temperature region (below 500 K) is attributed to hopping of weakly bonded electrons among Sn 2+ ⇔ Sn 4+ or Sn 3+ ⇔ Sn 4+ sites and that in the high temperature region (above 500 K) to hopping of doubly ionized oxygen vacancies (V o ). Complex plane impedance analysis have been made to understand the conduction behaviour of grain and grain boundaries separately.