Ba_(6-3x)(Nd_(1-y)Bi_y)_(8+2x)Ti_(18)O_(54)系微波介电陶瓷的研究

研究了Ba_(6-3x)(Nd_(1-y)Bi_y)_(8+2x)Ti_(18)O_(54)(x=0～1)陶瓷微波性能,并对其微观机理和晶体结构进行分析.随Bi_2O_3含量的增加,系统介电常数(ε)迅速增大,品质因数与频率的乘积(Q·f)逐渐减小.掺入Bi_2O_3后,系统中出现具有高ε的Bi_4Ti_3O_(12)晶相,并形成了类填满型钨青铜结构,阳离子极化增强,因此ε随Bi_2O_3含量的增加而增大.实验表明,当y=0.25～0.3时,Ba_(6-3x)(Nd_(1-y)Bi_y)_(8+2x)Ti_(18)O_(54)(x =0～1) 陶瓷具有优良的微波介电性能,其主要工艺条件和性能参数为烧结温度1 200 ℃保温4 h,ε≈102～107,Q·f≈20 000～22 000 GHz(1 GHz测量), 容量温度系数|αc|<10×10~(-6)/℃.

The Investigation of Ba_(6-3x)(Nd_(1-y)Bi_y)_(8+2x)Ti_(18)O_(54) Microwave Dielectric Ceramics

The microwave properties of Ba_(6-3x)(Nd_(1-y)Bi_y)_(8+2x)Ti_(18)O_(54)(x =0～1)system were investigated,and the micro-mechanism and the crystal structure were analyzed.The results indicated that the dielectric constant increased greatly while the Q·f value decreased with the increase of Bi_2O_3 content.These phenomena were related to the appearance of a new phase Bi_4Ti_3O_(12),which has high dielectric constant. Besides, full-filled tungsten bronze-like structure should be formed,the polarization of positive ions were enhanced.So,the samples doped with Bi_2O_3 presented higher dielectric constant.The experimental results showed that Ba_(6-3x)(Nd_(1-y)Bi_y)_(8+2x)Ti_(18)O_(54) ceramics exhibited excellent microwave dielectric properties at y=0.25～0.3.The main technological conditions and the parameters were as follows: the sintering temperature of 1 200 ℃,the holding time of 4 h,ε≈102～107,Q·f≈20 000～22 000 GHz(Measured at 1 GHz) and the capacity-temperature coefficient of |α_c|<10×10~(-6)/℃.