Ba_xSr_(1-x)TiO_3-Mg_2TiO_4复合陶瓷的相结构与介电性能

Phase structure and dielectric properties of Ba_xSr_(1-x)TiO_3-Mg_2TiO_4 composite ceramics

采用常规电子陶瓷工艺方法制备不同Ba/Sr比的Ba_xSr_(1-x)TiO_3-Mg_2TiO_4复合陶瓷,利用XRD、SEM、EDS及介电性能测试手段研究Ba/Sr比对复合陶瓷相结构及介电性能的影响。结果表明:制备的复合陶瓷由Ba_xSr_(1-x)TiO_3和Mg_2TiO_4两相组成,没有其他杂相出现;随着Ba/Sr比的减小,材料居里转变温度Tc向低温移动,室温介电常数、介电损耗和介电常数可调度均减小,而材料的优化因子却增大。组成为30%Ba_(0.45)Sr_(0.55)TiO_3-70%Mg_2TiO_4的复合陶瓷综合介电性能最优,在25℃、10k Hz条件下测得该陶瓷的介电常数为76.5,介电损耗为0.000 7,材料的介电可调度为10.2%(电场强度为2 kV/mm),适用于制作微波可调谐器件。

The Ba^Srj ,TiO3-Mg2TiO4 composite ceramics with different Ba/Sr ratios were fabricated via a conventional ceramic processing technique. The phase structure and dielectric properties of composite ceramics were investigated by XRD, SEM, EDS, and dielectric property measurements. The results show that the main phases of sintered ceramics are Ba, Sr~.,TiO3 and Mg2TiO4, without forming the impurity phases. As the Ba/Sr ratio decreases, the Curie temperature of composite ceramic shifts to the low temperature, which induces the permittivity, dielectric loss, and dielectric tunability decrease dramatically, while the figure of merit increases. The excellent dielectric properties are obtained with ceramic composite of 30% Bao4~Sr0.ssTiO3-70% Mg2TiO4. At 10 kHz and 25 ~C, the dielectric constant and loss tangent are 76.5, 0.000 7, respectively. The dielectric tunability is about 10.2% under a DC electric field of 2 kV/mm. It is promising to be utilized in tunable microwave device.