Effect of glass additions on the sintering and microwave properties of composite dielectric ceramics based on BaO–Ln 2O 3–TiO 2 (Ln = Nd, La)

Abstract

Ten weight percent BBZS (Bi 2O 3, B 2O 3, ZnO and SiO 2) glass was added to x(Ba 4Nd 9.333Ti 18O 54) − (1 − x)(BaLa 4Ti 4O 15) (BNLT, 0 ≤ x ≤ 1) composite dielectric ceramics to lower their sintering temperature whilst retaining microwave properties useful for low temperature co-fired ceramic and antenna core technology. With the addition of 10 wt% BBZS glass, dense BNLT composite ceramics were produced at temperatures between 950 and 1140 °C, depending on composition ( x), an average reduction of sintering temperature by 350 °C. X-ray diffraction, scanning and transmission electron microscopy and Raman spectroscopy studies revealed that there was limited inter-reaction between BLT/BNT and the BBZS glass. Microwave property measurement showed that the addition of BBZS glass to BNLT ceramics had a negligible effect on ɛ r and τ f , although deterioration in the measured quality factor ( Qf) was observed. The optimised composition ( xBNT − (1 − x)BLT)/0.1BBZS ( x = 0.75) had ɛ r ∼ 61, τ f ∼ 38 ppm/°C and Qf ∼ 2305 GHz.