诱导异常结晶法制备大尺寸钛酸锶钡单晶

Preparation of extra-large barium strontium titanate single crystals by an induced abnormal grain growth method

基于固相反应法和溶胶-凝胶法相结合的工艺,采用诱导异常结晶法(IAGG)在1 230~1 350℃制备了高质量的超大钛酸锶钡(Ba0.6Sr0.4)TiO3(BST60/40)单晶。通过XRD、SEM和TEM等手段对BST60/40单晶进行了微观结构的表征。研究了烧结温度、BST60/40粉末掺入量与溶胶前驱体基体的比例等对单晶形貌演化的影响,并讨论了IAGG的现象机理。结果表明:在掺入量-基体比例一定的条件下,当晶粒从异常生长到正常长大转变时,BST60/40单晶达到最大的临界尺寸。分析了IAGG法制备的BST60/40陶瓷块体的介电性和铁电性。由此得出:陶瓷的居里温度提高到20℃;在10℃、100 Hz下存在明显的电滞回线,自发极化强度Ps为8.65μC·m^-2,剩余极化强度Pr为1.79μC·m^-2,矫顽电场强度Ec为0.17 kV·mm^-1。

Based on the solid state reaction and sol-gel methods,high quality extra-large Ba0.6Sr0.4TiO3(BST60/40)single crystals were produced by an induced abnormal grain growth(IAGG)method at 1 230~1 350℃via a hybrid processing.The XRD,SEM and TEM were introduced to measure microstructure and confirmation of(BST60/40)single crystals.In addition,we investigated the effects of morphology evolution of the single crystal as function of processing parameters such as temperature and BST60/40 powder filler and sol-gel precursor matrix ratios,and discussed the mechanism of IAGG method proposed in detail.Our experimental results show that the exaggerated BST60/40 single crystal grains approach the critical grain size when the transition from IAGG to normal grain growth(NGG)occurs.The Curie temperature is increased to 20℃at 10~100 kHz and the ferroelectric hysteresis loop is obviously observed with the values of Ps,Pr and Ec of about 8.65μC·cm^-2,1.79μC·cm^-2 and 0.17 kV·mm^-1 measured at 100 Hz and 10℃,respectively.