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Single Crystal Growth and Domain Control of Potassium Niobate Crystals by Vertical Bridgman method

垂直布里奇曼法铌酸钾晶体的单晶生长和域控制

基本信息

批准号：
18360007
负责人：
HOSHIKAWA Keigo
金额：
$ 10.97万
依托单位：
Shinshu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18360007/
关键词：
Potassium Niobate Vertical Bridgman method Piezoelectricity Polarization process Top-seeded solution growth Platinum crucible ウエハ加工 KN単結晶 LN単結晶 SAWWフィルタ X線トポグラフ UWB無線システムリネージ小傾角境界

项目摘要

Potassium niobate (KNbO_3: KN) is known as a great piezoelectric materials which has large piezoelectric constant and electro-mechanical coupling coefficient. Therefore, KN is expected to be one of the future piezoelectric materials instead of lead-containing piezoelectric ceramics, and it has also been attracting attention as the substrate of filter devices with wide band using surface acoustic wave. However, KN is an incongruent-melting material, therefore, it is widely believed that a KN single crystal can be only grown by solution growth that means the top-seeded solution growth (TSSG) method. In our previous study, we showed that KN single crystals 10 mm in diameter could be grown by vertical Bridgman (VB) method. In this study, growth of KN single crystal 1 inch in diameter was demonstrated by VB method and the electric properties of the grown KN crystal was investigated.Powdered K_2CO_3 and Nb_2O_5 were mixed in a ratio of K_2CO_3 : Nb_2O_5 = 52.5 : 47.5 mol%, and the mixture was compressed and was calcined. The resulting columned compounds were used as the raw materials. A z-directional KN single crystal was used as the seed, RN crystals 1 inch in diameter were grown by VB method in air. A platinum crucible was used for the growth, and the growth rate was 0.5 mm/h. After the growth, the crystal was cooled slowly near temperatures of its phase transformation. The crystals were cut into wafers and polished, and the wafers were examined by X-ray topography. After the polarization process, the piezoelectricity of the polarized VB-KN samples was evaluated by using impedance analyzer. As the results, cloudy multi-domain KN crystals were grown by VB method. It was confirmed by X-ray topography that the grown crystals were almost single crystal. After the polarization process, the VB-grown KN single crystal revealed piezoelectricity similar as that grown by TSSG method.

铌酸钾(KNbO_3：KN)是一种重要的压电材料，具有较大的压电常数和机电耦合系数。因此，KN有望取代含铅压电陶瓷成为未来的压电材料之一，作为利用声表面波制作宽带滤波器件的衬底也备受关注。然而，KN是一种非均匀熔融材料，因此，人们普遍认为KN单晶只能通过溶液生长，即顶部种子溶液生长(TSSG)方法。在我们以前的研究中，我们发现用垂直布里奇曼(VB)法可以生长出直径为10 mm的KN单晶。采用VB法生长了直径1英寸的KN单晶，并研究了KN晶体的电学性能。将K2CO3和Nb2O5粉末按K2CO3：Nb2O5=52.5：47.5mol%的比例混合，压缩后焙烧。以所得到的柱状化合物为原料。以z向KN单晶为晶种，用VB法在空气中生长了直径1英寸的RN单晶。生长采用铂金坩埚，生长速度为0.5 mm/h，生长结束后，在相变温度附近缓慢冷却。晶体被切割成晶片并抛光，晶片进行了X射线形貌检查。极化处理后，利用阻抗分析仪对极化后的VB-KN样品的压电性进行了评价。结果表明，用VB法生长出了云状多域KN晶体。X-射线形貌分析表明，生长的晶体几乎为单晶。在极化过程后，VB生长的KN单晶表现出与TSSG法生长的KN单晶相似的压电性。