通过提拉法制备了LuxY1-xAlO3：Ce晶体样品. 采用偏光显微镜、场发射扫描电镜、电子探针等手段, 并结合热应力分析, 研究了LuxY1-xAlO3：Ce晶体中的开裂、铱金包裹体、气泡、孪晶、解理等宏观缺陷. 结果表明, 不同形态晶体内热应力合力的方向导致不同的开裂面的取位方式, 加强保温、建立适应晶体形态的合适温场等有助于获得完整晶体. 高温熔体及保护气氛中微量氧对铱坩埚的熔蚀与氧化, 使得晶体中存在有铱金包裹体, 降低炉腔内的氧含量、采用高纯度铱金压铸制作坩埚等措施有助于减少晶体内的铱金包裹体. 适当提高熔体温度以降低粘度、降低炉内气压等措施有助于减少晶体中的气体包裹物. 低镥含量LuxY1-xAlO3：Ce晶体中, a、b轴方向的晶胞参数非常接近, 在应力诱导作用下晶格参数互换易导致在<110>方向上形成孪晶.
LuxY1-xAlO3：Ce single crystal samples were prepared by the Czochralski method. By adopting micropolariscope, field emission stereoscan, electron probe and thermal stress analysis, the macroscopic defects in LuxY1-xAlO3：Ce single crystals such as split, iridium inclusion, gas hole, gas cavity, twin, cleavage were investigated. It is supposed that, in the crystals of different shapes, the direction of the composite force of thermal stress varies, thus resulting in the different orientations of cracked section. Factors including enhancing heat preservation, installing a suitable temperature field in accordance with crystal shapes may contribute to the acquisition of perfect LuxY1-xAlO3：Ce single crystals. High temperature melt erodes iridium crucibles, and the microcontent oxygen in protective atmosphere oxidizes iridium crucibles, thus resulting in the iridium inclusions in LuxY1-xAlO3：Cesingle crystals. Decreasing oxygen content in the furnace, pressure die casting iridium crucibles using iridium of high purity and other factors may help reduce iridium inclusions. With increasing melt temperature moderately to decrease its viscosity and air pressure in the furnace, gas inclusions decrease. The cell parameters a and b are very close in LuxY1-xAlO3：Ce single crystals with low Lutetium content, and the adjacent cell parameters interchange with the inducement of stress, thus leading to twining along <110> direction.
参考文献
| [1] | 丁栋舟(DING Dong-Zhou, et al), 陆 晟, 潘尚可, 等. LuxY1-xAlO3:Ce晶体中伴生(Lu,Y)3Al5O12:Ce相成因研究. 无机材料学报(Journal of Inorganic Materials), 2008, 23(3): 434-438. |
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