Effects of Forming Gas Annealing on Ba4Nb2O9 Ceramics
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.
Chengming Li, Chengbao Jiang, Zhiyong Zhong and Yichun Zhou
Y. Meng and W. P. Chen, "Effects of Forming Gas Annealing on Ba4Nb2O9 Ceramics", Materials Science Forum, Vol. 687, pp. 275-278, 2011