Applying the chemical bonding theory of single crystal growth to a Gd₃Ga₅O₁₂Czochralski growth system: both thermodynamic and kinetic controls of the mesoscale process during single crystal growth

Abstract

The chemical bonding theory of single crystal growth was applied to a Gd 3 Ga 5 O 12 (GGG) Czochralski growth system. On the basis of anisotropic chemical bonding characteristics, the mesoscale process controlled by both thermodynamics and kinetics has been studied in GGG single crystal growth. Starting from the unit-scale in the growth system, the mesoscale structures undergo evolution from GdO 8 , GaO 6 , and GaO 4 to Gd 3 Ga 5 O 12 clusters and to a GGG single crystal via chemical bonding between Gd, Ga, and O. On the basis of the chemical bonding theory of single crystals, the GGG single crystal thermodynamically prefers to exhibit a hexagonal configuration along the [111] pulling direction. Kinetically, isotropic mass transfer in the Czochralski growth process leads to formation of a GGG single crystal with a circular configuration, as viewed down along the [111] direction. In such a case, the GGG single crystal maintains the lowest energy. In order to satisfy both thermodynamic and kinetic controls, the thermodynamically preferred {−110} microfacets are exposed on the microscale and the single crystal adopts a circular shape on the macroscale. The present work deepens our understanding of the mesoscale process in the GGG Czochralski growth system.

Effect of Cr on long-persistent luminescence of near-infrared phosphor Zn3Ga2Ge2O10:Cr3+

“…2e and f are SEM images of the 0.5PL sample. Compared with those of 0.5DH and 0.5PH, the agglomeration phenomenon could not be observed clearly and the particles are small (average size: 1μm), since different sintering temperatures can create different growth kinetics of system [12][13][14], influencing compact degree and size. …”

Melilite-Type Oxide SrGdGa3O7: Bulk Crystal Growth and Theoretical Studies upon Both Chemical Bonding Theory of Single Crystal Growth and DFT Methods

“…On the basis of the anisotropic structure, we can establish the relationship between the growth rate along the [ uvw ] direction and the anisotropic chemical bonding energy density. The anisotropic growth rate can be expressed by − .where E uvw Bond is the chemical bonding energy of the interface along the [ uvw ] direction, A uvw is the projection area of the SGGM growth unit along the [ uvw ] direction at the growth interface, d uvw is the increased height on the ( hkl ) surface when the growth units incorporated into the lattice along the [ uvw ] direction, and K is the function of growth parameters, which is a constant for any [ uvw ] directions when we calculate the thermodynamic morphology. E uvw Bond , A uvw , and d uvw are used to calculate the anisotropic chemical bonding energy density.…”

Bulk crystal growth and characterization of 2.5–5.0 µm mid-infrared laser crystals

“…CdSe熔点为1240℃, 它具有两种结构类型, 即六方 结构和立方结构, 禁带宽度1.74 eV, 透过波段0.75~25 µm [6] . 该晶体密度为5.74 g/cm 3 [38,39] Er:GGG晶体在 4 I11/2和 4 I13/2能级的寿命可知 [17,30] : 随着 表 4 几种Er 3+ 激活石榴石结构晶体的光谱参数对比 [44] 晶 体 类 型 吸 收 截 面 σa 图 10 Cr-Er-Tm(Eu, Ho)的敏化机理图 [45] 发射, 研究结果表明Cr 3+ 可显著增强晶体对氙灯泵浦 光的吸收和利用效率 [45,46] ; 再如, 图11 Yb-Er-Pr的敏化 机理图中的Yb 3+ , 研究结果表明它可以显著增强晶体 对LD泵浦光的吸收和利用效率 [40] . 在Er 3+ 激活晶体中, 也可同时共掺与下能级有相近能级位置的稀土离子作 为退激活离子, 例如图10中的Tm 3+ , Eu 3+ 和Ho 3+ , 以及 http://engine.scichina.com/doi/10.1360/N092016-00155 图 11 (网络版彩图)Yb-Er-Pr的敏化机理图 [40] 图11中的Pr 3+ , 研究表明这些共掺的退激活离子与激活 离子之间存在有效的能量传递, 使得基质晶体中激活 离子获得合适的下能级寿命, 有助于提高中红外激光 输出的效率和功率 [40,45] .…”