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11.
The thermal and flow transport in an inductively heated Czochralski crystal growth furnace during a crystal growth process is investigated numerically. The temperature and flow fields inside the furnace, coupled with the heat generation in the iridium crucible induced by the electromagnetic field generated by the RF coil, are computed. The results indicate that for an RF coil fixed in position during the growth process, although the maximum value of the magnetic, temperature and velocity fields decrease, the convexity of the crystal‐melt interface increases for longer crystal growth lengths. The convexity of the crystal‐melt interface and the power consumption can be reduced by adjusting the relative position between the crucible and the induction coil during growth. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
12.
In this paper, photorefractive properties of Mg:Ce:Cu:LiNbO3 crystals were studied. The crystals doped with different concentration of Mg ions have been grown by the Czochralski method. Mg concentrations in grown crystals were analyzed by an inductively coupled plasma optical emission spectrometry (ICP‐OE/MS). The crystal structures were analyzed by the X‐ray powder diffraction (XRD), ultraviolet‐visible (UV‐Vis) absorption spectra and infrared (IR) transmitatance spectra. The photorefractive properties of crystals were experimentally studied by using two‐beam coupling. In this experiment we determined the writing time, maximum diffraction efficiency and the erasure time of crystals samples with He‐Ne laser. The results showed that the dynamic range (M/#), sensitivity (S) and diffraction efficiency (η) were dependent on the Mg doping concentration, and the Mg(4.58mol%):Ce:Cu:LiNbO3 crystal was the most proper holographic recording media material among the six crystals studied in the paper. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
13.
Ce∶LuAG晶体是一种性能优良的闪烁材料,但采用提拉法生长Ce∶LuAG时,经常出现开裂和包裹物缺陷。本文通过理论与实践相结合的方式分析了温度梯度、提拉速度、晶体旋转速度和热应变等因素对晶体产生缺陷的影响,并提出了解决办法,给出了适合生长优质Ce∶LuAG晶体的工艺参数:熔体上方温度梯度在5 ℃/mm左右,放肩角度在30°~60°,提拉速度1.0~1.5 mm/h,晶体旋转速度15~25 r/min。最后成功生长出直径30 mm、等径长50 mm质量较为完好的Ce∶LuAG单晶,晶体内核心面积小。 相似文献
14.
Haikuan Kong Jiyang Wang Huaijin Zhang Xin Yin Xiufeng Cheng Yanting Lin Xiaobo Hu Xiangang Xu Minhua Jiang 《Crystal Research and Technology》2004,39(8):686-691
La3Ga5.5Ta0.5O14 (LGT) crystal was grown by using the Czochralski method. The as‐grown crystal is transparent, free from inclusions and with no cracks. Specific heat, thermal expansion, dielectric constants, transmission spectrum and optical damage threshold of LGT have been measured, and the results show general properties of LGT are similar to that of La3Ga5SiO14 (LGS) crystal. The experiment to research the Q‐switch properties of LGT has been performed and the results show LGT possesses smaller electrooptic coefficients than that of LGS and may not be an ideal material used as a Q‐switch. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
15.
A high optical quality erbium doped Lu2SiO5 single crystal has been grown by the Czochralski method. The distribution coefficient of Er3+ was measured to be ∼0.926. The absorption and emission spectra as well as the fluorescence decay curve of the excited state 4I13/2 were measured at room temperature. The spectroscopic parameters were calculated using the Judd–Ofelt theory, and the J–O parameters Ω2, Ω4 and Ω6 were found to be 4.451×10-20, 1.614×10-20 and 1.158×10-20 cm2, respectively. The room-temperature fluorescence lifetime of the Er3+4I13/2→4I15/2 transition was measured to be 7.74 ms. The absorption and emission cross-section as well as the gain cross-section in the eye-safe regime of 1400–1700 nm were also determined and discussed. 相似文献
16.
采用提拉法沿a轴和c轴生长出无色透明的GdVO4单晶,质量均超过50g.用X射线荧光分析法测得两个主要元素Gd和V的分凝系数都接近1.室温下测量了GdVO4晶体的X射线粉末衍射图,确定所获GdVO4晶体属于四方晶系,D194h-I41/amd空间群.通过晶体的锥光干涉图确定GdVO4晶体为单轴晶,光轴方向平行于c轴且光学均匀性比较好.利用高分辨X射线衍射仪测量GdVO4晶体的摇摆曲线,结果表明生长的GdVO4晶体的晶格完整性较好.通过浮力法测得其室温下密度为5.478g/cm3.透过波谱表明透过波长大于340nm. 相似文献
17.
M. F. Lazarescu D. Pantelica A. S. Manea R. V. Ghita F. Negoita 《Journal of Crystal Growth》2002,240(3-4):401-406
We found Oxygen-doped GaAs crystals to be suitable materials for CO2 laser optical component preparation, with application at 10.6 μm. An optical transmission of 55% in the IR spectrum range, between 2 and 15 μm has been reached for such a GaAs type material. The GaAs crystals that we have analysed were grown by two procedures: Horizontal Bridgman (HB) and Liquid Encapsulated Czochralski (LEC). The HB method has been used for obtaining pure (undoped) crystals, while the oxygen-doped GaAs ingots were grown by LEC technique. The two types of samples processed in the same manner as regards mechanical polishing and chemical etching, which were investigated by Hall measurements, optical transmission spectrometry and elastic recoil detection analysis (ERDA) technique. The GaAs:O (LEC) has near semi-insulating properties as can be observed from the results of the electrical resistivity and Hall effect measurements. The ERDA spectrum shows an intense signal of oxygen in the bulk of GaAs:O (LEC) crystals, while the oxygen signal is not present in the ERDA spectrum of the undoped GaAs (HB). We consider that these results could recommend the ERDA technique as a possible qualitative and quantitative analysis in an ion-beam accelerator for oxygen content in oxygen-doped GaAs crystals. The analysis is not sensitive to the native oxide, as could be seen by measuring GaAs (HB) undoped crystals. 相似文献
18.
19.
Dongzhen Li Xiaodong Xu Yan Cheng Shishu Cheng Dahua Zhou Feng Wu Changtai Xia Jun Xu Jian Zhang 《Journal of Crystal Growth》2010,312(14):2117-2121
A Yb3+-doped CaYAlO4 laser crystal has been grown by the Czochralski technique. The segregation coefficient was measured by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). The cell parameters were analyzed with X-ray diffraction experiments. Color defects in Yb:CaYAlO4 have been evidenced to be similar to those in undoped CaYAlO4. The polarized absorption spectra and the fluorescence spectrum of the Yb:CaYAlO4 crystal were measured at room temperature. The fluorescence decay time of the Yb3+ ion was investigated. The results show that Yb:CaYAlO4 has potential as a laser gain medium for an ultrashort laser system. 相似文献
20.
Nd:LuVO4晶体的生长及其性能研究 总被引:2,自引:0,他引:2
采用提拉(Czochralski)法生长了Nd:LuVO4晶体.利用液相反应法,以V2O5和NH4OH生成NH4VO3,Nd2O3、Lu2O3和HNO3生成Nd(NO3)3和Lu(NO3)3反应制备多晶料;所生长Nd0.01Lu0.99VO4晶体为16×20×21 mm3,质量超过40g.以X射线荧光分析仪测得其生长中各主要元素的分凝系数.其中Nd3+约为0.91,V3+和Lu3+接近1.还测定了其介电常数ε11=27.2,ε33=33.9(30℃,1kHz),以同步辐射X射线白光形貌术观察了其内部质量. 相似文献