Low-Temperature Sintering of B₂O₃-Added Ba(Mg_1/3Nb_2/3)O₃ Ceramics

Abstract

The sintering temperature of Ba(Mg 1/3 Nb 2/3 )O 3 (BMN) ceramic is about 1450°C. When B 2 O 3 was added, BMN sintered at 900°C and it had a 1:2 ordered hexagonal structure. A liquid phase, which could be responsible for the decrease in sintering temperature, was observed in B 2 O 3 -added BMN. Mg 4 Nb 2 O 9 and Ba 2 B 2 O 5 second phases were found in the specimens and the Ba 2 B 2 O 5 second phase might be related to the liquid phase. The dielectric constant ( ε r ) and Q value increased with increasing sintering temperature and it is due to the increase in bulk density. However, they decreased with increasing B 2 O 3 content, which can be explained by the existence of the second phases. Good microwave dielectric properties of Q × f = 8500 GHz, ε r = 27.5 and temperature coefficient of resonance frequency (τ f ) = 27.0 ppm/°C were obtained for BMN with 2.0 mol% B 2 O 3 sintered at 930°C for 2 h.