Abstract
The effects of interfacial reaction of CuB 2 O 4 (CB)/BaTi 4 O 9 (BT4) and BaCuB 2 O 5 (BCB)/BaTi 4 O 9 (BT4) on densification, phase development and dielectric properties of BaTi 4 O 9 (BT4) have been investigated. With BaO present, the wetting of BCB/BT4 improves significantly in comparison to CB/BT4 at temperatures below 925 °C. However, the enhancement in densification becomes less significant for BCB+BT4 than that of CB+BT4 at reduced temperatures. The above results are attributed to a chemical reaction taking place at the interface of CB/BT4 and BCB/BT4 during firing, which becomes less extensive with BaO present in the sintering promoter. For both CB+BT4 and BCB+BT4 systems, the resulting composites have a dielectric constant of 36-40, product (Q·f r ) of quality factor (Q) and resonant frequency (f r ) of 13,000-21,000 GHz, and a temperature coefficient of resonant frequency (τ f ) of 20-40 ppm/°C in the temperature range of 25-80 °C. © 2012 Elsevier Ltd and Techna Group S.r.l.