We adjusted the B site excess ratio and the quantity of additional Bi2O3 in the KNN calcined powder in order to establish a process to fabricate, (K,Na)NbO3 (KNN)-based single crystals, with large and uniform configurations and relatively stable low porosity, using the seed-free solid-state crystal growth method. When the activity of abnormal grain growth during sample heating was controlled appropriately by adding 0.5 wt% Bi2O3 into the calcined powder with a B site excess ratio of 1%, extraordinarily large unitary rectangular single crystals were grown successfully. The individual crystals started to grow from the nucleus around the center of the green compacts formed by the calcined powder. Then they expanded until they became larger than 15 × 15 mm2 by heating at 1060 °C for 15 h. The relative density of the fabricated single crystals was higher than 99%.

中文翻译：

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通过调整 B 位过量比率和额外的 Bi2O3，使用无籽固态晶体生长方法生长大的单一 (K,Na)NbO3 单晶

我们调整了 KNN 煅烧粉末中 B 位过量率和额外 Bi2O3 的数量，以建立一种制造基于 (K,Na)NbO3 (KNN) 的单晶的工艺，具有大而均匀的构型和相对稳定的低孔隙率，使用无籽固态晶体生长方法。通过在B位过量率为1%的煅烧粉末中加入0.5wt%的Bi2O3，适当控制样品加热过程中异常晶粒生长的活动，成功生长出特大的单一矩形单晶。单个晶体开始从由煅烧粉末形成的生坯中心周围的核生长。然后通过在 1060 °C 下加热 15 小时，它们膨胀直至大于 15 × 15 mm2。