Effects of Forming Gas Annealing on Ba4Nb2O9 Ceramics

Abstract

Ba4Nb2O9 ceramics were synthesized via solid state reaction and sintered in air. Annealing in 5%H2 + 95%N2 at 900°C for 2 h resulted in an increase in leakage current by several orders of magnitude, and obvious increases in low-frequency capacitance and dielectric loss, while re-oxidation in air at 900°C for 2 h led to a partial recovery. It is proposed that oxygen vacancies and Nb4+ were formed through annealing in the reducing atmosphere while inverse process occurred in the re-oxidation treatment. Re-oxidation is helpful to improve the properties of barium niobates ceramics sintered or heat-treated in reducing atmospheres and further investigations are desirable.