钒酸钇双折射晶体生长及缺陷观察

Growth and Defects Observation of YVO_4 Birefringent Crystal

采用在较低氧分压的保护气氛中用提拉法(Cz法)生长YVO4晶体,采用自行设计的气压计,精密调节炉内的氧、氮比例,有效防止了晶体生长中的过度缺氧,生长出Ф33mm×31mm(等径)YVO4晶体。设计了生长YVO4晶体最佳工艺条件:转速5～10r·min-1,拉速:2～6mm·h-1,生长周期:24h,液面上8mm温度梯度2.875℃·mm-1。用偏光显微镜对YVO4晶体的裂纹、散射颗粒、包裹物、偏心生长等缺陷进行观察,认为它们的成因主要是生长速率过快,生长环境中湿度大及晶体中存在分解和挥发性物质等。

The crystal growth in protective atmosphere with a little oxygen partial pressure based on the Czochralski (Cz) technique was presented To prevent crystal from oxygen deficiency, the ratio of oxygen and nitrogen in the stove was precisely adjusted YVO 4 crystal with Ф33 mm×31 mm(equal diameter) was grown The optimum process: rotating at 5～10 r·min -1 , pulling speed at 2～6 mm·h -1 , growing cycle at 24 h, and the temperature gradient is 2 875 ℃·mm -1 at 8mm above liquid surfaces Under the polarized microscope, the crystal surface defects including cracking, scatter particulate, inclusion, helix growth were observed The reason should be the following factors: over fasting growth speed, high relative humidity, the decomposable and volatile matter in the crystal