Ba1–xSrxAl2Si2O8系陶瓷晶体结构及微波介电性能

Crystal Structure and Microwave Dielectric Properties of Ba1-xSrxAl2Si2O8 Ceramics

采用固相反应法制备Ba1-xSrxAl2Si2O8 （x=0,0.050,0.075,0.100,0.150）介质陶瓷。通过热分析、密度、X射线衍射和扫描电子显微镜等研究Sr2＋对Ba1–xSrxAl2Si2O8陶瓷的晶体结构及微波介电性能的影响。结果表明：Sr2＋可以有效促进六方相钡长石转变为单斜相钡长石,且当x≥0.075时,转变率达到100%。在x=0.050时,六方相与单斜相共存,样品密度ρ和介电常数εr最小。在0.050≤x≤0.100范围内,随着Sr2＋含量的增加,样品密度、介电常数和品质因数Q×f均增大。在0.050≤x≤0.150范围内,随着x值的增大,具有单斜钡长石相样品的谐振频率温度系数向负的方向呈线性发展。Ba1-xSrxAl2Si2O8在1 425℃烧结时微波介电性能最佳：εr=5.95,Q×f=26 619 GHz,τf=–25.1×10^–6 K^–1。

Ba1-xSrxAl2Si2O8 （x=0, 0.050, 0.075, 0.100, 0.150） ceramics were prepared by a solid-state reaction method. The effect of Sr2＋ on the crystal structure and microwave dielectric properties of Ba1-xSrxAl2Si2O8 ceramics was investigated by thermal analysis, density measurement, X-ray diffraction and scanning electron microscopy, respectively. The results show that Sr2＋ doping promotes a phase transformation from hexacelisian to monocelsian, and the transformation ratio reaches up to 100% when xi〉0.075. The hexacelisian and celsian coexist in ceramics as x=0.050, giving the minimum density （p） and dielectric constant （εr）. Moreover, the density, dielectric constant and quality factor （Qxf） of Ba1-xSrxAl2Si2O8 ceramics increase with the increase of Sr2＋ content as 0.050≤x≤0.100. The resonant frequency temperature coefficient of the samples becomes negative linearly with the increase of Sr2＋ content as 0.050≤x≤0.150. The Ba1-xSrxAl2Si2O8 sintered at 1425 ℃ shows the optimum microwave dielectric properties （i.e.,Qxf=26 619 GHz,εr=5.95 and τf=-25.1×10^-6 K^-1）.