Effect of Ba(Y1/2Nb1/2)O3 and BaZrO3 on the cation order and properties of Ba(Co1/3Nb2/3)O3 microwave ceramics

The effect of different solid solution additives and heat treatments on the cation order and dielectric properties of Ba(Co1/3Nb2/3)O3 (BCoN) were investigated. Pure Ba(Co1/3Nb2/3)O3 undergoes an order–disorder transition at ∼1400 °C, the Q value of the ordered phase (Q·f=64,400) is significantly higher than the disordered variant (Q·f=10,800). The substitution of BaZrO3 destabilizes the 1:2 order and a 1:1 ordered phase are formed for ∼10–20 mol% BZ. The order–disorder temperatures for the 1:1 BCoN–BZ phases are quite low (<1300 °C) and lead to lower degrees of order and lower Q values. The substitution of Ba(Y1/2Nb1/2)O3 (BYN) also induces a transition to 1:1 ordering, but in this case the stability of the order is significantly higher and the samples remain ordered to at least 1550 °C. The greater degree of order in the BYN system is accompanied by a higher Q values compared to their BZ counterparts, however none of the samples reach the Q values of the pure ordered BCoN end-member.