Abstract A modified seed mounting geometry is proposed, aiming to improve the distribution homogeneity of the supersaturation on the crystal face during the growth of ammonium dihydrogen phosphate (NH4H2PO4, ADP) crystals. To evaluate the modification, three dimension transient numerical simulation of flow and solute transfer involved in the growth of ADP crystals have been performed. The effects of flow on the surface supersaturation distribution is analyzed in detail. Compared with the ordinary seed mounting geometry, the modified geometry is able to suppress the formation of flow stagnation regions near the prismatic surface and improve the magnitude and the distribution homogeneity of the supersaturation. Particularly even at a lower rotation rate (ω = 30 rpm), the distribution of the surface supersaturation still possesses a better uniformity under the modified geometry. Meanwhile, with the increase of rotation rate, there is an improvement in the magnitude and the distribution of the supersaturation on the crystal surfaces. The effects of natural convection adjacent to prismatic faces can be ignored when rotation rate is equal to or greater than 50 rpm. Moreover, as the crystal size increases, the magnitude of the supersaturation on the prismatic surface declines a little, and its uniformity deteriorates gradually. Consequently, as the crystal growing, it should increase the rotation rate appropriately. Finally, etching studies reveal that the ADP crystals with higher quality can be obtained by modifying the seed mounting geometry simply.

中文翻译：

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通过改进的种子安装几何形状分析 NH4H2PO4 晶体溶液生长的流动和传质

摘要 为了提高磷酸二氢铵（NH4H2PO4，ADP）晶体生长过程中晶面上过饱和度的分布均匀性，提出了一种改进的种子安装几何形状。为了评估修改，已经进行了涉及 ADP 晶体生长的流动和溶质转移的三维瞬态数值模拟。详细分析了流动对表面过饱和度分布的影响。与普通的种子安装几何形状相比，改进的几何形状能够抑制棱柱表面附近流动停滞区域的形成，提高过饱和度的大小和分布均匀性。特别是即使在较低的转速下 (ω = 30 rpm)，在改进的几何形状下，表面过饱和度的分布仍然具有更好的均匀性。同时，随着转速的增加，晶体表面过饱和度的大小和分布都有所改善。当转速等于或大于 50 rpm 时，可以忽略棱柱面附近自然对流的影响。而且，随着晶体尺寸的增大，棱柱表面的过饱和程度略有下降，其均匀性逐渐变差。因此，随着晶体的生长，应适当提高转速。最后，蚀刻研究表明，通过简单地修改种子安装几何形状，可以获得更高质量的 ADP 晶体。随着转速的增加，晶体表面过饱和度的大小和分布都有所改善。当转速等于或大于 50 rpm 时，可以忽略棱柱面附近自然对流的影响。而且，随着晶体尺寸的增大，棱柱表面的过饱和程度略有下降，其均匀性逐渐变差。因此，随着晶体的生长，应适当提高转速。最后，蚀刻研究表明，通过简单地修改种子安装几何形状，可以获得更高质量的 ADP 晶体。随着转速的增加，晶体表面过饱和度的大小和分布都有所改善。当转速等于或大于 50 rpm 时，可以忽略棱柱面附近自然对流的影响。而且，随着晶体尺寸的增大，棱柱表面的过饱和程度略有下降，其均匀性逐渐变差。因此，随着晶体的生长，应适当提高转速。最后，蚀刻研究表明，通过简单地修改种子安装几何形状，可以获得更高质量的 ADP 晶体。当转速等于或大于 50 rpm 时，可以忽略棱柱面附近自然对流的影响。而且，随着晶体尺寸的增大，棱柱表面的过饱和程度略有下降，其均匀性逐渐变差。因此，随着晶体的生长，应适当提高转速。最后，蚀刻研究表明，通过简单地修改种子安装几何形状，可以获得更高质量的 ADP 晶体。当转速等于或大于 50 rpm 时，可以忽略棱柱面附近自然对流的影响。而且，随着晶体尺寸的增大，棱柱表面的过饱和程度略有下降，其均匀性逐渐变差。因此，随着晶体的生长，应适当提高转速。最后，蚀刻研究表明，通过简单地修改种子安装几何形状，可以获得更高质量的 ADP 晶体。