Influence of Copper(II) Oxide Additions to Zinc Niobate Microwave Ceramics on Sintering Temperature and Dielectric Properties

The effect of CuO additions on the firing temperature of ZnNb 2 O 6 ceramics was investigated using dilatometry, transmission electron microscopy, and X‐ray diffractometry. A 5 wt% CuO addition to ZnNb 2 O 6 ceramics significantly lowered the firing temperature from 1150° to ∼900°C. The presence of a CuO‐rich intergranular phase in the specimen was observed and was evidence of the formation of a liquid phase during sintering. The composition of the liquid phase was (ZnCu 2 )Nb 2 O 8 . In particular, the low‐fired ZnNb 2 O 6 ceramics had good microwave dielectric characteristics— Q × f = 59 500, ɛ r = 22.1, τ f =–66 ppm/ o C. These properties were correlated with the formation of a second phase, (ZnCu 2 )Nb 2 O 8 .