在外加直流偏置电场作用下,钛酸锶钡(BST)固溶体铁电材料具有随着电场强度增加而介电常数降低的非线性特征,是相控阵天线移相器材料的研究热点.而铝酸镧陶瓷介电常数温度系数可达接近零,介电损耗正切值低,可小于1×10~(-4).为降低BST材料的介电损耗和介电常数,以铝酸镧为改性剂对Ba_0.6Sr_0.4TiO_3材料进行了掺杂.当铝酸镧的含量为4%时,Ba_0.6Sr_0.4TiO_3材料的介电常数降低到85(100 kHz),介电损耗降低到0.00041(100 kHz),而Ba_0.6Sr_0.4TiO_3材料的介电可调性保持在20%左右.X射线衍射图谱表明烧结后得到的BST材料具有典型的钙钛矿结构. SEM图像观察发现,4%比例的掺杂量使得陶瓷致密度较高,晶粒均匀.
Ba_xSr_(1-x)TiO_3 (BSTO, 0≤x≤1) is a solid solution ferroelectric material exhibiting non-linear change of large dielectric constant with an applied dc electric field. It has been shown that the dielectric constants and losses of barium strontium titanate can be reduced by doping certain oxides. In this paper, we presented systematic studies of the effect of LaAlO_3 on BSTO bulk ceramics. When content of LaAlO_3 ceramics got to 4% in the Ba_0.6Sr_0.4TiO_3 sample, dielectric constant of Ba_0.6Sr_0.4TiO_3 was 85(100 kHz) and dielectric losses was 0.00041(100 kHz), but the relative tunability of Ba_0.6Sr_0.4TiO_3 still maintain in 20%. X-ray diffraction analyses indicated that the samples consist of perovskite phase. Scanning electron microscopy micrograph of BST sample indicated the grain size decreased and the density increased.
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