论文部分内容阅读
The structures and dielectric properties of Ba_(6-3x)Nd_(8+2x)Ti_(18)O_(54)system(x=2/3)doped with different contents of Bi_2O_3,whose final molecular formula is Ba_(6-3x)(Nd_(1-y)Bi_y)_(8+2x)Ti_(18)O_(54)were investigated.It is indicated that the dielectric constant increases greatly whereas Q value(f_0=4 GHz)decreases with the increase of Bi_2O_3 content.However,the temperature coefficient could be controlled below 0±30×10~(-6)/℃in the experiment. These phenomena are related to the appearance of a new phase,Bi_4Ti_3O_(12),which has high dielectric constant. Also,that Bi~(3+)(0.13 nm)substitutes for Nd~(3+)(0.099 5 nm)will increase the unit cell volume,which will lead to the enlargement of the octahedron B site occupied by Ti~(4+).So the spontaneous polarization of Ti~(4+)ions will be strengthened.Besides,Bi~(3+)will fill up some vacancies which Ba~(2+)or Nd~(3+)ions leave in two Al sites and four A2 sites.More positive ions polarize,which also contributes to higher dielectric constant.The samples got with the optimium properties are sintered at 1200℃for 4 h,when 3,=0.25,ε≈110,Q≈5 400(f_0=4 GHz),TCC=4.7×10~(-6)/℃;When y=0.3,ε≈120,Q≈5 000(f_0=4 GHz),TCC=24×10~(-6)/℃.
The structures and dielectric properties of Ba_ (6-3x) Nd_ (8 + 2x) Ti_ (18) O_ (54) system with x = 2/3 doped with different contents of Bi_2O_3, 3x) (Nd_ (1-y) Bi_y) _ (8 + 2x) Ti_ (18) O_ (54) were investigated. It is indicated that the dielectric constant increases significantly reduces Q value (f_0 = 4 GHz) of Bi 2 O 3 content. However, the temperature coefficient could be controlled below 0 ± 30 × 10 -6 / ° C in the experiment. These phenomena are related to the appearance of a new phase, Bi_4Ti_3O_ (12), which has high dielectric Also, that Bi to (3 +) (0.13 nm) substitutes for Nd ~ (3 +) (0.099 5 nm) will increase the unit cell volume, which will lead to the enlargement of the octahedron B site occupied by Ti ~ (4 +). So the spontaneous polarization of Ti ~ (4 +) ions will be strengthened.Besides, Bi ~ (3+) will fill up some vacancies which Ba ~ (2+) or Nd ~ (3+) ions leave in two Al sites and four A2 sites. Positive positive ions polarize, which also contributes to higher dielectric con stant.The samples got with the optimium properties are sintered at 1200 ° C for 4 h, when 3, = 0.25, ε≈110, Q≈5 400 (f_0 = 4 GHz), TCC = 4.7 × 10 -6 / ℃; When y = 0.3, ε≈120, Q≈5000 (f_0 = 4 GHz), TCC = 24 × 10 -6 / ℃.