0.2wt% Bi_2O_3、CuO、B_2O_3对5Ca_(0.6)La_(0.267)TiO_3-5Ca(Mg_(1/3)Nb_(2/3))O_3微波介质陶瓷的性能影响

Effect of 0.2wt% Bi_2O_3,CuO,B_2O_3 on the Properties of 5Ca_(0.6)La_(0.267)TiO_3-5Ca(Mg_(1/3)Nb_(2/3))O_3 Microwave Dielectric Ceramics

采用传统的固相反应法,研究了三种烧结助剂Bi2O3、CuO、B2O3对5Ca0.6La0.267TiO3-5Ca(Mg1/3Nb2/3)O3微波介质陶瓷的烧结性能和介电性能的影响。实验结果表明,掺入0.2wt%的Bi2O3、CuO、B2O3产生了液相,有效地降低了体系的烧结温度。Bi2O3和CuO的加入没有改变烧结体的微观形貌,它们介电常数和品质因数随烧结温度的变化趋势和体积密度趋于一致,均在体积密度最大时最高。当温度大于1300℃时,加入0.2wt%B2O3试样有柱状晶体生成,并随着烧结温度的升高而增多,柱状晶体的存在可能促使Q×f值较大的提高,当烧结温度过高时(1350℃),由于柱状晶体过多使得烧结体不均匀导致Q×f值下降。Bi2O3、CuO、B2O3的加入没有改变烧结体的晶相组成,因此所有烧结体均有近零的温度系数。结果表明,加入0.2wt%B2O3的5Ca0.6La0.267TiO3-5Ca(Mg1/3Nb2/3)O3在1325℃烧结温度具有最佳的介电性能:εr=54.87,Q×f=55 726 GHz,τf=-0.6 ppm/℃。

The effects of 0.2wt% Bi2O3、CuO、B2O3 additions on the microwave dielectric and sintering properties of 5Ca0.6La0.267TiO3-5Ca（Mg1/3Nb2/3）O3 ceramics prepared by conventional solid-state route were investigated.The generation of liquid-phase resulted from the addition of Bi2O3、B2O3 and CuO effectively decreased the sintering temperature.The addition of Bi2O3 and CuO did not influence the grain morphology of the specimens and with the increase of sintering temperature,the dielectric constants and quality factors both shifted the same variation as that of density,which reach the maximum when the specimens have the highest density.Small amount of columnar grains appear in specimens doped with 0.2wt%B2O3 when the sintering temperature reaches 1300 ℃ and the amount of the columnar crystals increases with increasing sintering temperature.The significant increase of Q×f values for B2O3 doped specimens may be related to the formation of columnar grains.However,when sintered at 1350 ℃,excessive columnar grains resulted in the decrease of Q×f values.The addition of Bi2O3、B2O3 and CuO has little effect on the phase composition,so no significant variation in the τf values for the specimens was observed.The 5CLT-5CMN ceramics doped with 0.2wt%B2O3 and sintered at 1325℃ have the optimal microwave dielectric properties： εr=54.87,Q×f=55 726 GHz,τf=-0.6 ppm/℃.