Low temperature preparation of the Zn2SiO4 ceramics with the addition of BaO and B2O3

Abstract

The Zn2SiO4 ceramics with the addition of BaO and B2O3 are fabricated by traditional solid-state preparation process at a sintering temperature of 900 °C. The introduction of BaO and B2O3 to the binary system ZnO-SiO2 is achieved by adding 10 and 20 wt. % flux BB to the mixed ZnO-SiO2 ceramic powders pre-sintered at 1,100 °C, respectively. The chemical composition of the flux BB (50 wt.%BaO-50 wt.% B2O3) is located at a liquid phase zone with a temperature range of about 869–900 °C in the binary diagram BaO-B2O3. In addition, the introduction of BaO and B2O3 to the binary system ZnO-SiO2 is also achieved by the means of a chemical combination of H2SiO3, H3BO3, ZnO and Ba(OH)2·8H2O, which can result in the formation of the hydrated barium borates with low melting characteristics. In turn, by the liquid sintering aid of the barium borate melts, the preparation process of the Zn2SiO4 ceramics can be further simplified. In the two preparation methods, the Zn2SiO4 ceramics with the 1.5–2.0 ZnO/SiO2 molar ratios and the addition of a 10 wt. % flux BB can show good dielectric properties whereas the bending strength mainly depends on the microstructure of the Zn2SiO4 ceramics and SiO2 content in the composition of the specimen.