复相陶瓷(0.5BaO0.5SrO)[(1-y)TiO_(2y)Nb_2O_5]的介电性能研究(英文)

DIELECTRIC PROPERTIES OF (0.5BaO0.5SrO)\ COMPOSITE CERAMICS

通过对组成进行一定的过量控制,利用传统陶瓷工艺,成功制备了具有钙钛矿相钛酸锶钡固溶体和钨青铜相铌酸锶钡固溶体两相稳定共存的(0.5BaO0.5SrO)[(1-y)TiO2yNb2O5](BSTN)复相陶瓷。用RiguakuD/max-2400型X射线衍射仪和KEITHLEY3330阻抗分析仪对所得样品的相结构状态及介电性能进行了测试。结果表明:y值在0.1～0.7之间的BSTN复相陶瓷为钙钛矿相和钨青铜相两相稳定共存的复合相;在该范围以外,则为单一相的钛酸锶钡与Nb或铌酸锶钡与Ti的固溶体。复相陶瓷的介电性能取决于钙钛矿相和钨青铜相的相对含量及其固溶度,当组成y约为0.7时,介电常数达到最大值;随测试频率的提高,介电常数和损耗降低。复相陶瓷中钨青铜相的铁电/顺电相转变温度与钨青铜相中固溶TiO2量相关,随固溶量增加,转变温度降低。同时,受复相陶瓷中钙钛矿相的影响,随钙钛矿相相对含量的增加,转变温度升高;钨青铜相的最低铁电/顺电相转变温度出现在约110℃,比Sr0.5Ba0.5Nb2O6下降约240℃。

Barium strontium titanate niobate composite ceramics were successfully prepared in situ by controlling excess components according to the formula (0.5BaO0.5SrO) [(1-y)TiO2yNb2O5] (BSTN) and by using the traditional ceramic process. The phase composition and dielectric properties of the composite ceramics were investigated by XRD and impedance analyzer. The results show that the perovskite phase and the tungsten bronze phase can be coexisted stably in BSTN when 0.1&ley&le0.7. The dielectric properties of the composite ceramics are dependent on the relative contents of these two phases and the solid solubility of Nb2O5 in the perovskite phase and TiO2 in the tungsten bronze phase, respectively. The dielectric constant reaches to a maximum value when y=0.7. Both dielectric constant and dielectric loss decrease with the increase of the applied frequency for the same y value. The Curie temperature of the tungsten bronze phase decreases as the solid solubility of TiO2 increases in the phase, moreover, increases as the content of perovskite phase increases in the composite ceramics. The lowest temperature of ferroelectric/paraelectric phase transition for the composite ceramics is at about 110°C and it is 240°C lower than that of the Sr0.5Ba0.5Nb2O6.