共查询到18条相似文献,搜索用时 111 毫秒
1.
2.
3.
4.
5.
通过对K2WO4和K2W2O7两种助溶剂的对比、分析,选择K2W2O7做助溶剂,采用顶部籽晶(TSSG)法生长YbKGW晶体.设计了合理的工艺条件转速10~15r/min;降温速率0.05℃/h;生长周期15d.通过对YbKGW晶体粉末样品的X-ray衍射谱与KGW粉末样品的X-ray衍射谱对比分析,生长晶体为β-YbKGW晶体.利用TG-DTA测定YbKGW晶体的熔点及相变温度分别是1086℃和1021℃.通过对晶体缺陷的观察分析认为,晶体裂缝及包裹物等缺陷与生长工艺条件密切相关,应尽量减少生长过程中的温度、浓度及生长速度的波动,保持晶体的稳态生长. 相似文献
6.
7.
光学浮区法是近些年来倍受关注的晶体生长的新方法,具有无需坩埚、无污染、生长速度快等优点,十分适合于晶体生长研究。介绍了光学浮区法晶体生长炉的构造以及技术原理,并阐述了该生长法在晶体生长领域的应用情况。 相似文献
8.
9.
10.
以SmBaCuO超导晶粒为籽晶,制备了具有大晶粒的YBaCuO超导块材。磁化强度和交流磁化率表明该材料具有较强的磁通钉扎和良好的晶界妆特性,较强的磁通钉扎使大块样品在磁化后能冻结大量磁通,表现出很好的剩磁性能,经0.5T永磁体化后,实验测得其表面剩磁场最大值为0.125T,且在短时间内这一剩磁场没有明显的衰减。 相似文献
11.
12.
为了研究媒晶剂在石膏晶体转晶过程中的作用,同时探讨计算机模拟在研究过程中的应用,本文利用吸附能模型计算了石膏晶体晶型以及主要晶面的附着能,同时模拟了柠檬酸、乙二胺四乙酸和苯基甘氨酸3种媒晶剂与石膏晶面(1 2-1)和(0 1 1)反应,得出了媒晶剂与石膏晶面的吸附能及媒晶剂的最佳组合方式.利用扫描电子显微镜对实验所得石膏晶型进行了分析,并测得不同媒晶剂作用下磷石膏抗折抗压强度.研究发现,实验结果与计算机模拟结果基本一致,磷石膏最大抗折抗压强度分别为3.64和7.35 MPa. 相似文献
13.
温度梯度和生长速率对CdZnTe-VBM生长晶体的影响 总被引:3,自引:0,他引:3
计算模拟了半导体材料CdZnTe垂直布里奇曼法(CdZnTe-VBM)单晶体生长过程,分析了炉膛温度梯度和坩埚移动速率对结晶界面形态和晶体内组份偏析的影响。计算结果表明炉膛温度梯度和生长速率的变化明显影响固-液界面前沿对流场的形态和强度。界面凹陷深度随着炉膛温度梯度的增加和生长速率减小而减小。炉膛温度梯度的增加和生长速率的减小虽然均能有效的减小径向偏析,但却增加轴向偏析,减小轴向等浓度区的长度。 相似文献
14.
15.
Jianqin Zhang Shenglai Wang ChangShui Fang Xun Sun Qingtian Gu Yiping Li Bo Wang Bing Liu Xiaoming Mu 《Materials Letters》2007,61(13):2703-2706
KDP crystals were grown from the aqueous solution with different concentrations of sulphate by both the traditional temperature-lowering method and the rapid growth method. Sulphate showed a great effect on the growth and the properties of KDP crystals. With the rise of the dopant concentration, many defects occur such as mother liquid inclusions, parasite crystals and cracks. When the dopant concentration of sulphate reaches a certain value, the ultraviolet transmittance of crystals decreases a lot compared with crystals at low dopant concentration. 相似文献
16.
A new microstructure, thornball, of zinc oxide (ZnO) was synthesized by a very simple solid vapor deposition process under lead oxide (PbO) atmosphere. The microthornballs consist of numerous needles, which extend outwards in all directions symmetrically. They have dimensions of 120 μm in diameter, while the average diameter of the needles is about 100-200 nm. The needles on the balls grow along the 〈0 0 0 1〉 orientation and have gradient compositions along radial. Control experiments proved that PbO played an important role in the growth. Additionally, photoluminescence property was observed and provided the evidence that PbO did not deteriorate the optical properties of ZnO thornballs. This kind of microstructures has potential applications in the field of photochemical catalysis. 相似文献
17.
Chunjuan Tang 《Journal of Experimental Nanoscience》2014,9(2):161-166
Zinc sulphide (ZnS) nanotubes were synthesised via simple surfactant emulsion template under hydrothermal conditions. X-ray diffraction, scanning electron microscopy and transmission electron microscope were used to characterise the nanotubes. The results indicate that the nanotubes are composed of nanoparticles. The diameters of the nanotubes vary from 300 to 700?nm and lengths range from 1 to 2?µm. In addition, it is found that the reaction time, reaction temperature and cetyltrimethylammonium bromide play key roles in the phase and morphology control of ZnS nanotubes. Furthermore, room temperature photoluminescence was recorded to investigate the optical property of the obtained product. The stable and strong green emission band centred at 513?nm was attributed to some self-activated centres, probably vacancy states or interstitial states related to the peculiar structure. 相似文献
18.
8 at.% Yb:YAG plate single crystal with the dimension of 170 mm × 150 mm × 30 mm was grown in vacuum by Horizontal Directional Solidification method. Aimed at blue-green color centers, annealing treatments of 15 mm × 15 mm × 1 mm samples from 900 °C to 1400 °C for 5 h and at 900 °C from 5 h to 40 h in air were conducted. The absorption spectra, emission spectra, fluorescence lifetime and X-ray photoelectron spectroscopy of samples under different annealing conditions were measured at room temperature, respectively. Annealing at above 1000 °C for 5 h or at 900 °C for 40 h made the blue-green color centers disappear and the samples turned to transparent. Absorption coefficients decreased in the 300 nm–800 nm wavelength range, emission intensities increased and emission bands broadened around 486 nm and 1029 nm with increasing temperature up to 1200 °C, then varied inversely. These values decreased or increased monotonically with increasing annealing time at 900 °C. The maximal increases of fluorescence lifetime were 62.3% and 64.7%, respectively. The calculated emission cross section of 1200 °C for 5 h was up to 4.4 × 10−20 cm2. In X-ray photoelectron spectroscopy, the concentrations of oxygen vacancies reduced from 1.28% down to absence by annealing. These experiments show that color centers are detrimental to the optical properties of HDS-Yb:YAG laser crystal and optimal annealing treatments should be conducted. 相似文献