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本文报道了Sr2+离子掺杂对GdVO4晶体生长和拉曼性能的影响.SrxGd1-xVO4晶体粉末经X射线粉末衍射分析,其结果仍属四方晶系,具有锆英石结构.实验表明,高掺杂浓度时,Sr2+离子不易取代Gd3+离子进入GdVO4晶体的晶格,易导致SrxGd1-xVO4晶体开裂和产生包裹体.XPS实验证明,SrxGd1-xVO4晶体中钒元素为+5价.同时测试了常温下SrxGd1-xVO4晶体的拉曼光谱,发现随着Sr2+离子浓度增加,在884cm-1处的VO4反对称伸缩振动逐渐增强,表明Sr2+离子的掺入影响了GdVO4晶体的拉曼性能. 相似文献
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水热法和熔盐法生长的Nb: KTP晶体成分和结构研究 总被引:1,自引:1,他引:0
利用激光剥蚀-电感耦合等离子体质谱、X射线衍射分析、显微激光拉曼光谱等测试手段研究了掺铌磷酸钛氧钾(Nb: KTP)晶体成分对结构的影响,分析比较了水热法和熔盐法生长的Nb: KTP晶体中Nb的含量及分布特征、晶体结构和化学键特征峰的变化等.结果表明:由于Nb的影响和NbO6八面体的收缩效应,Nb: KTP晶体的轴长发生了微小变化,晶胞体积有所减小,TiO6八面体和PO4基团的拉曼特征峰有不同程度漂移,其中水热法和熔盐法Nb: KTP晶体的有效分凝系数分别为0.268和0.348.同时,研究指出在Nb: KTP晶体生长时,应确定合理的掺Nb量. 相似文献
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用电阻加热提拉法生长了一系列较大尺寸,组分离子均匀性较好的铌酸钾锂晶体.利用X射线荧光光谱法测量了不同配比的熔体中生长出的晶体组成,用同步辐射X射线测量了晶体结构,结果表明随晶体组成变化,晶体的晶格常数发生了变化.根据晶体组分离子浓度与折射率的关系研究了晶体折射率变化情况,结果表明用本方法生长的大尺寸KLN晶体,寻常折射率no在测量误差范围内没有变化,非寻常折射率ne的变化率在820nm仅为1.22×10-4/mm,在410nm仅为1.93×10-4/mm.晶体的干涉条纹证明了晶体有良好的光学均匀性.结合晶体生长实验,探讨了改进晶体组分离子浓度分布均匀性的方法,结果表明采用籽晶和坩锅向相同方向旋转可以改善晶体生长界面处组分离子浓度的波动,提高晶体组分离子均匀性.晶体的缺陷研究表明晶体结构完整性较好,位错形状与晶体结构相一致,密度为7.5×104,[001]轴是晶体的极化轴.晶体对890~960nm波长范围的cw-Ti:sapphire激光倍频结果表明晶体有良好的倍频性能. 相似文献
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采用提拉法(CZ法),生长出质量良好的Er3+:NaY(W0.9Mo0.1O4)2晶体.通过X射线粉末衍射,红外光谱分析,并与NaY(WO4)2相比较,得到Er3+:NaY(W0.9Mo0.1O4)2晶体的结构与NYW类似,仍为四方晶系的白钨矿结构,I4(1)/α空间群.测定了晶体的实际组成,得到晶体中各元素均按理论值进行掺杂,计算了掺杂离子的分凝系数约为1.15.在光谱性质上,测试了晶体的吸收光谱,及晶体在50~1000cm-1波数范围内的拉曼光谱,并计算了各吸收峰的半峰宽及吸收系数A. 相似文献
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对三联苯是一种常见的有机闪烁剂,通常用作闪烁计数器的发光材料。对三联苯闪烁晶体具有对中子探测效率高以及不易潮解等特性,这使其在实际应用中具有广阔的前景。本文采用坩埚下降法,使用单层安瓿成功生长出φ12 mm×30 mm对三联苯晶体。在生长开始前通过差热分析,确定晶体的生长温度。生长完成后测试了晶体粉末的X射线衍射谱、摇摆曲线、红外光谱、荧光光谱和拉曼光谱。X射线衍射结果表明,生长的晶体为纯对三联苯相。从摇摆曲线结果可以看出,生长晶体质量良好。红外和拉曼分析结果显示,峰位并没有出现明显的偏移,表明晶体中杂质含量较少并未引起晶体分子化学结构的变化。荧光光谱没有杂质峰的出现也说明对三联苯晶体存在较少杂质或晶格缺陷。 相似文献
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M. N. Palatnikov O. B. Shcherbina N. V. Sidorov K. Bormanis 《Crystallography Reports》2010,55(5):811-814
Lithium niobate single crystals doped with lanthanides (Gd, Er) and nominally pure single crystals of congruent and stoichiometric
compositions have been grown under time-dependent thermal conditions. Regular growth domain microstructures and periodic nanostructures
have been investigated by optical microscopy and atomic force microscopy with a step from 10 to 100 nm. Comparative investigations
of the Raman spectra of lithium niobate single crystals of different compositions have been performed. 相似文献
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KLN, Fe:KLN, Mn:KLN and Cu:KLN crystals were grown by Czochraski method. The structure of crystal was measured by X‐ray diffraction technique. The results indicated that the doped crystals kept the same structural characteristics as the pure KLN crystal, but the lattice constants of Fe:KLN and Mn:KLN crystals became smaller than that of pure KLN crystal, and that values of Cu:KLN crystal became larger than that of pure KLN crystal. This indicated that Fe and Mn cations replaced Nb cation, and Cu cation replace K cation after they entered into the lattice of KLN crystal. The result of ultraviolet‐visible absorption spectra was identified with that of X‐ray diffraction analysis. 相似文献
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Single crystalline and crack free potassium lithium niobate (KLN) single crystals with low Li content were grown by the Czochralski method. The crystal composition can be written as K2.60Li1.17Nb5.44O15 (=K2.95Li1.33Nb6.17O17) which contain relatively fewer Li ions than ferroelectric K3Li2Nb5O15 crystals. All experimental results show that the deficiency of the Li ions in the KLN crystals strongly influences their physical properties. Especially, the as‐grown crystals do not indicate any signature for a ferroelectric phase transition in contrast to the ferroelectric K3Li2Nb5O15 crystals. However, due to ionic conduction, the temperature dependence of the dielectric constant of such KLN‐2 crystals show a broad anomaly near 300°C. In addition, the existence of proton defects can be revealed by infrared absorption spectroscopy near 3500 cm‐1 in as‐grown crystals. 相似文献
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Xu Jiayue Fan Shiji Lin Yafang Xu Xuewut 《Progress in Crystal Growth and Characterization of Materials》2000,40(1-4):137-144
Transparent KLN crystals 10mm in diameter and 25 to 45mm in length have been grown by the modified vertical Bridgman technique from different melts in the range of 3035mol% K2O, 1723mol% Li2O and 4350mol% Nb2O5. The growth conditions are a growth rate of less than 0.25 mm/hr, temperature gradient in solid-liquid interface of 23 °C/mm and growth direction of <110>. As-grown KLN crystals have tetragonal tungsten bronze structure. Most of the as-grown crystals do not crack when cooling through the paraelectric/ferroelectric phase transition. 180° domain structures are observed after the KLN crystal was etched in boiling 2HNO3:Hf. Dielectric properties and transmission spectrum of the as-grown KLN crystals are measured. 相似文献
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M. N. Palatnikov I. V. Biryukova O. B. Shcherbina N. V. Sidorov O. V. Makarova N. A. Teplyakova 《Crystallography Reports》2016,61(6):1031-1038
A series of lithium niobate (LiNbO3) crystals of congruent and stoichiometric compositions, doped with erbium, have been grown under non-steady-state thermal conditions. A series of LiNbO3:Zn crystals, nominally pure LiNbO3 crystals of congruent and stoichiometric compositions, and a LiNbO3:B crystal have also been grown. Both growth conditions and concentration dependences of physicochemical, ferroelectric, and structural characteristics of LiNbO3:Er crystals are investigated. The growth regular domain microstructures and periodic nanostructures in LiNbO3:Er crystals are analyzed by optical microscopy and atomic force microscopy (AFM). A comparative study of the optical homogeneity and photorefractive properties of LiNbO3:Er crystals of congruent and stoichiometric compositions and the Raman spectra of LiNbO3 crystals of different compositions is performed. 相似文献
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Y. T. Song X. L. Chen W. J. Wang W. X. Yuan Y. G. Cao X. Wu 《Journal of Crystal Growth》2004,260(3-4):327-330
The growth conditions and mechanism of hexagonal GaN platelet crystals by Li flux were studied. The experimental results confirmed that these crystals crystallized from Li–Ga–N liquid phase. Photoluminescence (PL) spectra and Raman scattering spectrum of the crystals were obtained, which show that GaN crystals obtained by this method possess good crystalline quality. 相似文献
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Phase-matched wavelength in potassium lithium niobate (KLN) crystals grown by the micro pulling down (μ-PD) method dependent on the atomic displacement changed by melt composition was investigated. It has been found that the polar components of the atomic displacement of the metal atoms Nb(1) and Nb(2) increase with increasing Nb content of melt. Also, phase matched wavelength for second harmonic generation (SHG) properties was determined from ultra-violet to green region by increasing Nb content of melt. 相似文献
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Gisele Maxwell Alan Petersen Dylan Dalton Bennett Ponting 《Journal of Crystal Growth》2012,352(1):59-62
Potassium lithium niobate (KLN) is a nonlinear optical material with a high nonlinearity. It has the potential to improve the performance and reduce the cost of blue and UV lasers. KLN crystals are not commercially viable because growth by traditional techniques is not possible. In an effort to develop commercially viable KLN, single crystals of the material were grown by the laser heated pedestal growth method (LHPG) with compositions of x=0.02, 0.06 and 0.2 following K3Li2?xNb5+xO15+2x. Noncritical phase matching at 20 °C for previously unreported compositions of x=0.02 and 0.06 was measured at 795 nm and 805 nm, respectively. Overall, the results suggest that single crystal KLN can be used for SHG into the UV region of the spectrum and can be developed into a commercially viable nonlinear optical material. 相似文献
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The Raman scattering spectra of various forms of GeSe2, such as amorphous films, single crystals, and small crystals prepared by a gas-evaporation deposition technique, are investigated with an excitation photon energy ranging from 2.1 to 2.8 eV. In the spectra of the crystals, there are two Raman bands, originating from two types of breathing vibrations of the GeSe4/2 tetrahedra: one is spread over the corner-sharing tetrahedra and the other is quasi-localized on the edge-sharing tetrahedra. In addition to the resonant Raman scattering related to the edge-sharing tetrahedra through the exciton transition observed with 2.71 eV excitation in the single crystals, a new resonant spectrum is found only in the small crystals with 2.54 eV excitation. With increasing disorder in the crystals, the intensity ratio between the two breathing vibration bands increases in the off-resonant excitation region. The Raman spectra in the amorphous states are ascribed to the breathing vibrations of GeSe4/2 tetrahedra which form a medium-range structure topologically similar to that of crystalline fragments. 相似文献