MgO含量对Ba_(0.55)Sr_(0.45)TiO_3的掺杂/复合效果研究

Study on MgO doped/composite Ba_(0.55)Sr_(0.45)TiO_3 ceramics

采用传统的固相反应法制备得到MgO掺杂Ba_(0.55)Sr_(0.45)TiO_3陶瓷,并对其相结构、微结构以及介电性能进行了系统的研究。随着MgO含量的增加,陶瓷样品的居里峰被明显的抑制和展宽,同时居里温度向低温方向移动,表明一定量的Mg2+进入BST晶格。探明了当加入少量MgO时导致在微波频段损耗因子增加的原因;而随着MgO含量的进一步增加,微波频段的介电损耗降低主要是由于介电相MgO的"复合"作用。结合拉曼光谱明显地观察到Mg^(2+)进入BST晶格破坏材料的微波性能,这来源于Mg^(2+)破坏了钙钛矿结构中B位有序度。在钙钛矿结构中,Q值强烈的依赖于A1(TO)延展模式的拉曼峰宽。同时,氧八面体对材料微波性能的影响起到了非常重要的作用。

MgO-doped Ba0.55Sr0.45TiO3 ceramics were prepared by solid-state reaction technique and their phase compositions,microstructure and dielectric properties were syste matically characterized.Their dielectric peaks were markedly suppressed,broadened,and shifted to low tempe ratures with increasing MgO content,indica-ting that certain amount of Mg^2 ＋ incorporated into BST lattice.The reason why the loss tangent at microwave frequencies increased with the addition of MgO at low concentrations was identified.The decrease in loss tan-gent at microwave frequencies of the samples with high contents of MgO was resulted from the ‘composite’ effect of the dielectric component.Raman spectra analysis clearly indicated that the incorporation of Mg^2 ＋ de-graded quality factor （Q value）of BST,which was ascribed to the deterioration of B-site ordering of the ABO3 perovskite structure.It was found that Q value was strongly correlated with the Raman peak width of A1（TO） stretch modes in perovskite materials.Also oxygen octahedron played an important role in determining the ma-terial’s microwave performance.