Low-temperature firing and microwave dielectric properties of BaTi4O9 with Zn-B-O glass system

The effect of Zn-B-O (ZB) glass additions on the sintering temperature and microwave dielectric properties of BaTi4O9 has been investigated using X-ray diffraction, scanning electron microscopy, dilatometry and electrical characterization. It was found that the addition of small amount of glass to BaTi4O9 lowered the sintering temperature to similar to 900 degreesC while maintaining good microwave properties. In sintered samples with ZB glass, plate-like abnormal grains (similar to5 mum) were observed. ZB glass heat-treated at 900 degreesC for 2 h was crystallized to Zn(BO2)(2) and Zn,(BO3)(2), which coincides with second phases detected in low-temperature fired BaTi4O9. Thus it can be concluded that there is a negligible reaction forming other second phases between BaTi4O9 and ZB glass. BaTi4O9 ceramics sintered at 900 degreesC for 2 h had good microwave dielectric properties: relative dielectric constant (epsilon (r)) = 33, quality factor (Qxf) = 27000, and temperature coefficient of resonant frequency (tau (f)) = 7 ppm/degreesC. (C) 2001 Elsevier Science Ltd. All rights reserved.