Effect of BA(Y_1/2Nb_1/2)O₃ and BaZrO₃ on the cation order and properties of Ba(CO_1/3Nb_2/3)O₃ microwave ceramics

The effect of different solid solution additives and heat treatments on the cation order and dielectric properties of Ba(Co_1/3Nb_2/3)O₃ (BCoN) were investigated. Pure Ba(Co_1/3Nb_2/3)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(Y_1/2Nb_1/2)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.