具有准同型相界(MPB)组成的化合物(Sr_(1-x)Ba_x)_2NaNb_5O_(15)的晶体生长及性质研究  

Growth and Properties of (Sr_(1-x)Ba_x)_2NaNb_5O_(15) Crystals with the MPB Composition

作　　者：仪修杰[1] 陈焕矗[1] 程振祥[1] 韩建儒[1] 曹文武[2] 翟剑庞[1] 杨长红[1] 姜付义[1] 

机构地区：[1]山东大学晶体材料国家重点实验室,济南250100 [2]香港城市大学物理与材料科学系

出　　处：《人工晶体学报》2004年第3期339-342,共4页Journal of Synthetic Crystals

基　　金：国家自然科学基金 (No .5 0 13 1160 73 7);研究资助局基金 (No .N CityU114 /0 1)联合资助项目

摘　　要：用Czochralski方法生长出铁电钨青铜型单晶 (Sr1-xBax) 2 NaNb5O15(简称SBNN) ,晶体沿c轴方向生长。正交 四方相的准同型相界 (简称为MPB)存在于x =0 .4 5～ 0 .5 0之间 ;SBNN晶体是不一致熔融的化合物 ,在晶体成长过程中 ,Sr2 + 的分凝系数比Ba2 + 的大 ,因此具有高浓度Ba2 + 的SBNN晶体很难生长。晶体的居里温度是 2 4 3℃ ,在此温度下的相变是弥散的 ,随频率的增加 ,介电常数降低。The ferroelectric tungsten bronze single crystals of the (Sr_(1-x)Ba_x)_2NaNb_5O_(15)(abbreviated as SBNN) were grown by the Czochralski method along the <001> direction. A orthorhombic-tetragonal morphotropic phase boundary (MPB) is shown to exist at x=0.45-0.50 by X-ray diffraction patterns. The chemical composition analysis revealed that SBNN single crystal is incongruent melting compound and the segregation coefficient of Sr^(2+) is larger than that of Ba^(2+). Therefore, it is difficult to grow the SBNN single crystal with high Ba^(2+) content during the crystal growth. The Curie temperature(T_c) is 243℃ and the phase transition is diffuse at this temperature.

关 键 词：MPB Czochralski方法 介电常数 铌酸锶钡钠 SBNN 铁电单晶 Sr1-xBax 

分 类 号：O782[理学—晶体学] TN304.9[电子电信—物理电子学]