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KDP晶体中包裹体形成机制的探讨 总被引:8,自引:8,他引:0
本文介绍了包裹体对KDP晶体质量的影响,并从两个方面探讨了KDP晶体生长过程中包裹体的形成机制.通过分析KDP晶体表面原子结构研究了不同杂质的吸附情况以及杂质对生长台阶的阻碍作用,通过分析晶体生长过程中流体动力学和质量输运条件的变化研究了旋转晶体的流体切应力和表面过饱和度,结果表明吸附杂质对生长台阶的阻碍和表面过饱和度的不均匀造成了生长台阶的弯曲和宏观台阶的形成,导致生长台阶形貌的不稳定是包裹体形成的重要原因. 相似文献
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大尺寸KDP(KH2PO4)晶体在切割过程中容易出现开裂现象,为了研究大尺寸KDP晶体切割过程中开裂机制并提出合理切割方案,本文对大尺寸KDP晶体切削效应进行了研究.大尺寸KDP晶体切削过程中刀片与晶体之间的接触应力和切割引起的热应力是晶体切削过程中主要致裂因素,因此本文采用有限元计算方法对KDP晶体切削过程进行热力耦合数值仿真模拟.结果表明切割过程中KDP晶体与刀片之间的压力应小于4.1 MPa,切口处温差应控制在4.2℃之内,同时本文还得到了切削过程可控参数(车床推进力和刀片的线速度)的安全取值范围,该范围的提出对KDP晶体的切割技术具有十分重要的意义. 相似文献
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《Journal of Crystal Growth》2006,286(1):108-113
The bond valence model is employed to calculate the bond strength of constituent chemical bonds formed between growth units in both potassium dihydrogen phosphate (KDP) and ammonium dihydrogen phosphate (ADP) crystals, with the aim to predict and control the crystal shape. After calculating and comparing the relative growth rates of all selected planes, which are related to the crystallographic structure and chemical bond strength, the natural morphology of both KDP and ADP can be conveniently deduced. To check the calculated results, the crystallites of KDP and ADP are grown under different growth conditions; their morphologies accord well with our theoretical calculations. Meanwhile, the influence of ethanol anti-solvent on crystal morphology is microscopically interpreted, which alters the crystal morphology by changing the supersaturation of the growing solution and influencing the bonding process. When ethanol is added into the growing solution, the crystal shape becomes slender. 相似文献
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The velocity and shape of growth layers on the {100} faces of ammonium dihydrogen phosphate (ADP) crystals growing in aqueous solution at pH = 5.0 are compared with those previously reported for growth at pH = 3.8. The results are interpreted in terms of the adsorption of hydrated hydroxonium ions on the crystal surface. 相似文献
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M. Ittu Zugrav A. Dumitrica A. Dumitras N. Comaniciu 《Crystal Research and Technology》1982,17(4):475-480
The deuterated homologue of potassium dihydrogen phosphate crystals (DKDP) was grown by a modified transport method. Experimental results concerning electrooptic characteristics of these single crystals used in construction of a Q-switch and a four-crystals modulator are presented. An infrared extension of KURTZ -ROBINSON model electrooptic effect is also given. 相似文献
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Guozong Zheng Jingkui Liang Zhengdong Li Genbo Su Xinxin Zhuang 《Crystal Research and Technology》2008,43(6):583-587
The combined effects of supersaturation and Ba2+ on potassium dihydrogen phosphate (KDP) were investigated in batch cooling suspension crystallization. Growth size, morphology, and impurity Ba2+ adsorbed in the KDP crystals were measured with changing Ba2+ concentration and supersaturation. Significant changes in shapes and volume of the grown crystals have been observed. The results further confirmed that the size and shape of crystals were greatly determined by supersaturation. Ba2+ ions significantly modified the growth habit of KDP crystals. The concentration of Ba2+ ions adsorbed in the crystals increases with the increasing Ba2+ ions in the solutions and supersaturation. The foggy phenomena caused by the addition of Ba to the KDP solution were also described. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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The dielectric properties of rapidly grown potassium dihydrogen phosphate KH2PO4 (KDP) crystals have been studied over a wide temperature range and compared with the properties of traditionally grown KDP crystals. It was found that the contribution of domains to permittivity in rapidly grown crystals is considerably less than in conventionally grown ones. The dielectric properties in various growth sectors of KDP crystals are determined. 相似文献
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Crystallography Reports - The effect of nonelectrolyte additives with hydrophilic and hydrophobic hydration on the growth of potassium dihydrogen phosphate (KH2PO) crystals in the kinetic mode at... 相似文献
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The investigations on the formation of mixed crystals of ammonium dihydrogen orthophosphate (ADP) and potassium dihydrogen orthophosphate (KDP) i.e. potassium ammonium dihydrogen phosphate, K1‐x(NH4)xH2PO4 have been presented in this paper. Pure and mixed crystals of ADP and KDP have been grown by slow evaporation technique from the supersaturated solution at an ambient temperature 26±1 °C for ammonium concentration x in the range 0.0 ≤ x ≤ 1.0 in the case of mixed crystals. Crystal compositions were determined by flame atomic absorption spectroscopy and chemical analysis. The results of the X‐ray analysis of the grown crystals are also reported. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were used to study the kinetic process of dehydration and the high temperature phase behaviour. DTA showed the distinct thermal events attributed to dehydration of ADP, KDP and K1‐x(NH4)xH2PO4. The results of thermal analysis and chemical analysis are consistent with each other. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Zhong De‐Gao Teng Bing Wang Shu‐Hua Jiang Xue‐Jun Li Ming He Lin‐Xiang Huang Wan‐Xia 《Crystal Research and Technology》2009,44(9):925-929
Mixed crystals of potassium dihydrogen phosphate and ammonium dihydrogen phosphate were grown onto point seeds by the method of temperature reduction. It was found that the regeneration process of z‐cut point seeds became more and more difficult with increasing KH2PO4 concentration in the solution mixture. The interior stress and cracking of the mixed crystals were analyzed by synchrotron X‐ray topography. Large numbers of stress stripes were found at the seed and sectors boundaries. The lattice parameters of the pyramid and prismatic sectors of the prepared mixed crystal were calculated according to the X‐ray diffraction patterns. With solution containing 8 mol % KH2PO4, the lattice volumes of the prismatic sector of the mixed crystal were 1.3% larger than that of the pyramid sector of the crystal. Chemical etching revealed microcracks with length of hundreds of microns in the mixed crystals, which tended to spread and led to crystal cracking. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Resonant diffraction of synchrotron radiation (SR) is a modern method of studying the structure and properties of condensed matter that can be implemented on third-generation synchrotrons. This method allows one to investigate local properties of media (including magnetic and electronic ones) and observe thermal vibrations, defects, and orbital and charge orderings. A brief review of the advance provided by SR resonant diffraction is presented, and the capabilities of this method for analyzing phase transitions are considered in more detail by the example of potassium dihydrogen phosphate and rubidium dihydrogen phosphate crystals. It is shown that the investigation of the temperature dependence of forbidden reflections not only makes it possible to observe the transition from para- to ferroelectric phase, but also gives information about the proton distribution at hydrogen bonds. 相似文献
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Single crystals of potassium dihydrogen phosphate, KH2PO4 (KDP), grown by isothermal evaporation at room temperature have been characterized by their measurement of electrical conductivity and dielectric behaviour. Implications in respect of practical utility of KDP crystals in devices have been given. 相似文献