The shrinking process and microwave dielectric properties of BaCu(B2O5)-added 0.85BaTi4O9–0.15BaZn2Ti4O11 ceramics

Abstract The effect of BaCu(B 2 O 5 ) (BCB2) addition on the shrinking process and microwave dielectric properties of 0.85BaTi 4 O 9 –0.15BaZn 2 Ti 4 O 11 (BZT) ceramics were investigated by the conventional solid-state ceramic route. Adding BaCu(B 2 O 5 ) into 0.85BaTi 4 O 9 –0.15BaZn 2 Ti 4 O 11 ceramics led to the formation of two new phases: Ba 4 Ti 13 O 30 and BaTi(BO 3 ) 2 . The densification of the 5–15 wt% BaCu(B 2 O 5 ) + BaTi 4 O 9 –BaZn 2 Ti 4 O 11 ceramics sintered at approximate 900 °C for 2 h was attributed to the liquid phase sintering mechanism formed by the meltdown of BaCu(B 2 O 5 ). The addition of BaCu(B 2 O 5 ) also increased the shrinkage rate and promoted the grain growth. Because of the improved densification, the dielectric constant of the samples sintered at 900 °C was increased from 29.5 to 32.2 with increasing BCB2 from 5 wt% to 15 wt%. However, the Q  ×  f value decreased sharply from 27,600 GHz to 15,900 GHz due to the progressively increased Ba 4 Ti 13 O 30 as well as the whisker glass phase. At last, good microwave dielectric properties with values of ϵ r  = 30.9, Q  ×  f  = 20,200 GHz and τ f  = +11.7 ppm/°C were obtained in the BZT ceramics with 11 wt% BCB2 sintered at 900 °C for 2 h. It was suitable for the low temperature co-fired ceramics (LTCC) applications.