标题：Morphological study of Czochralski-grown lanthanide orthovanadate single crystals and implications on the mechanism of bulk spiral formation
作者：Cong, Hengjiang; Zhang, Huaijin; Sun, Shangqian; Yu, Yonggui; Yu, Wentao; Yu, Haohai; Zhang, Jian; Wang, Jiyang; Boughton, Robert I.
作者机构：[Cong, Hengjiang; Zhang, Huaijin; Sun, Shangqian; Yu, Yonggui; Yu, Wentao; Yu, Haohai; Zhang, Jian; Wang, Jiyang] Shandong Univ, State Key Lab Crystal 更多
通讯作者地址：[Zhang, HJ]Shandong Univ, State Key Lab Crystal Mat, Jinan 250100, Peoples R China.
来源：JOURNAL OF APPLIED CRYSTALLOGRAPHY
摘要：Single crystals of monoclinic Nd:LaVO4 with dimensions up to empty set28 x 21 mm have been grown from the near-stoichiometric melt by the Czochralski method, making use of various seed orientations that are perpendicular to the (010), (10 (1) over bar), (001) and (00 (1) over bar) crystal planes. A sample was also prepared with the seed orientation in an arbitrary direction relative to the crystal. The anisotropic properties of the crystal are manifested in the growth morphology of the as-grown crystals, where different degrees of bulk spiral growth were observed. It was also found that employing the (001) or (00 (1) over bar) seed faces severely suppressed the bulk spiral growth, and thus high quality and large-scale Nd:LaVO4 crystals were obtained. The constituent segregation coefficients and high-temperature stability, including the melting point, were determined and evaluated. Based on the attachment energy model of Hartman-Perdok theory, morphology predictions were made for monoclinic LaVO4 and tetragonal YVO4 orthovanadate single crystals. Correlating with the as-grown morphology of both crystals developed along different seed orientations, a theoretical explanation is provided for the influences of seed crystals on bulk spiral formation, crystal quality and utilization ratio. It suggests that breaking the axial symmetry of the ideal atomic level interface between crystal and melt plays a crucial triggering role in bulk spiral formation in the Czochralski growth of lanthanide orthovanadate single crystals. Selecting a proper seed orientation that yields such a highly axially symmetric surface structure consisting of a series of large-area facets with similar growth velocities can greatly reduce bulk spiral formation and thus is preferable in the Czochralski growth of large-sized low-symmetry oxide crystals.