Preparation And Modification Of (Bi_1.5Zn_1.0Nb_1.5)O₇ And (Bi_1.5Zn_0.5)(Nb_0.5Ti_1.5)O₇ Ceramics

Along with the miniaturization and integration of communication equipments, microwave dielectric ceramics have been attracted widely attention as the critical material for microwave components, such as dielectric resonator, frequency filter, oscillator, and so on. Three basic requirements for microwave ceramics have been defined: a high dielectric constant, a low dielectric losses and a near-zero temperature coefficient of resonant frequencyÏ„f.Microwave dielectric ceramics of (Bi_1.5Zn_0.5)(Zn_0.5Nb_1.5)O₇ and (Bi_1.5Zn_0.5)(Ti_1.5Nb_0.5)O₇ have been widely noticed due to its high permitivity and low sintered temperature. However, their sintered process and general dielectric properties should also be optimized for their unstable sintered process and highÏ„f. In this paper, bismuth-based pyrochlore of (Bi_1.5Zn_0.5)(Zn_0.5Nb_1.5)O₇ and (Bi_1.5Zn_0.5)(Ti_1.5Nb_0.5)O₇ with low-temperature sintering were selected. The investigations were focused on the modification of dielectric properties and optimization the sintering process by substitution on A-sites of pyrochlore structure and doping sintered aids. The phase transition and mechanism of modification were also examined.The substitutions of Sm3+ and Y3+ on A-site bismuth cations of (Bi_1.5Zn_0.5)(Zn_0.5Nb_1.5)O₇ pyrochlore slightly raised the sintering temperature(from 1000 to 1100℃). The Sm3+ and Y3+ cations go into the bismuth-based pyrochlore through its replacement of Bi3+ cations on the A-site positions. The single-phase could be prepared for...