Tohoku University, Sendai, Japan.
IEEE Trans Ultrason Ferroelectr Freq Control. 2012 Sep;59(9):1868-71. doi: 10.1109/TUFFC.2012.2398.
We have grown shape-controlled langasite-type crystals by the micro-pulling-down (μ-PD) method. Columnar shaped La(3)Ta(0.5)Ga(5.5)O(14) (LTG), Ca(3)NbGa(3)Si(2)O(14) (CNGS), Ca(3)TaGa(3)Si(2)O(14) (CTGS), Sr(3)NbGa(3)Si(2)O(14) (SNGS), and Sr(3)Ta- Ga(3)Si(2)O(14) (STGS) crystals were grown using a Pt-Rh crucible with a 3-mm-diameter columnar die at the bottom. All grown crystals showed high transparency except for the peripheral area and diameter of approximately 3 mm. The chemical phases at the central parts of the grown crystals were identified as a single phase of langasite-type structure and their lattice parameters were almost the same as those of crystals grown by the Czochralski (Cz) method; however, some impurity phases were observed in the peripheral area. In X-ray rocking curve measurements, the grown crystals indicated equivalent crystallinity to the crystal grown by the Cz method. The piezoelectric constant d(11) of the CNGS crystal was 3.98 pC/N; this value is well correlated with those of previous reports.
我们已经通过微下拉（μ-PD）方法生长出了具有特定形状的 langasite 型晶体。使用底部带有 3mm 直径柱状模具的 Pt-Rh 坩埚生长出了柱状 La(3)Ta(0.5)Ga(5.5)O(14)（LTG）、Ca(3)NbGa(3)Si(2)O(14)（CNGS）、Ca(3)TaGa(3)Si(2)O(14)（CTGS）、Sr(3)NbGa(3)Si(2)O(14)（SNGS）和 Sr(3)Ta-Ga(3)Si(2)O(14)（STGS）晶体。除了约 3mm 直径的边缘区域外，所有生长的晶体都表现出了高透明度。生长晶体的中心部分的化学相被确定为 langasite 型结构的单相，其晶格参数几乎与提拉法（Cz）生长的晶体相同；然而，在边缘区域观察到了一些杂质相。在 X 射线摇摆曲线测量中，生长的晶体表现出与 Cz 法生长的晶体相当的结晶度。CNGS 晶体的压电常数 d(11)为 3.98pC/N，这与之前的报告中的值非常吻合。
