以直径3英寸Li2B4O7晶体为籽晶,采用改进型坩埚下降法在Pt坩埚中生长了直径105mm、长度120mm、无宏观缺陷的高质量Li2B4O7,晶体.生长速率<0.3mm/h,固液界面附近的温度梯度约为30℃/cm.探讨了开裂、孪晶、包裹体等缺陷的形成和消除办法,测试了该晶体的性能.介电常数ε11=9.33,压电系数d33=0.94C/m2,机电偶合系数k33=0.42.高机电偶合系数和低介电常数表明该晶体在高频声表面波器件应用方面具有很大的潜力.
High-quality and large size Li2B4O7 single crystals were grown by the modified vertical
Bridgman technique. Polycrystalline Li2B4O7 powders were synthesized as raw materials and 3-inch-diameter LBO single crystal
was used as seed. The growth speed was less than 0.3mm/h and the temperature gradient in solid-liquid interface was about 30℃/cm.
Twin-free, core-free and inclusion-free LBO single crystals with 105mm in diameter and 120mm in length were grown successfully. The formation and
elimination of cracks, twins and inclusions were investigated. SAW properties of as-grown LBO crystals measured are as follows: dielectric
constant ε11=9.33, piezoelectric constant d33=0.94C/m2 and coupling coefficient k33=0.42.
参考文献
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