Low‐Fire Processing of ZrO ₂ –SnO ₂ –TiO ₂ Ceramics

Abstract

Effects of a liquid‐phase‐sintering aid, BaCuO 2 + CuO (BCC), on densification and microwave dielectric properties of (Zr 0.8 Sn 0.2 )TiO 4 (ZST) ceramics have been investigated. The densification kinetics of ZST are greatly enhanced with the presence of 2.5–5 wt% BCC, but become retarded when the amount of BCC increases further. At a given BCC content, moreover, slower densification kinetics are observed with a larger particle size of ZST. The above results are attributed to a chemical reaction taking place at the interface of BCC/ZST during firing. The ZST dissolves into BCC, forming crystalline phases of ZrO 2 , SnO 2 , CuO, and BaTi 8 O 16 which reduce the amount of BCC flux available for liquid‐phase sintering. The crystallization kinetics become more significant, compared with densification kinetics, with increasing the amount of BCC and the particle sizes of ZST. For samples with 2.5–5 wt% BCC, a high relative sintered density is obtained at 1000°C and the resulting microwave ceramics have a dielectric constant and a value of Q at 7 GHz in the ranges of 35–38 and 2800–5000, respectively.