Nd:GGG晶体生长与开裂研究

本文采用提拉法(CZ)生长了Nd:GGG晶体,并从理论上讨论了包裹物、提拉速度、晶体转速和降温速率等因素对晶体开裂的影响,最后给出了生长元开裂Nd:GGG晶体的最佳工艺参数:径向温度梯度越小越好,纵向温度梯度在0.5℃/mm,提拉速度2～4mm/h,晶体转速20～40r/min,降温速率不超过20℃/h.通过设计合理而稳定的温场、选择最佳工艺参数及退火处理等方法,较好地解决了Nd:GGG晶体开裂问题.     

影响生长大尺寸和高质量β-BBO晶体的因素

本文讨论顶部籽晶法各种生长条件对大尺寸、高质量β-BaB2O4晶体的影响,诸如助熔剂、温度梯度、晶体转速、降温速率、籽晶方向等晶体生长工艺参数.采用NaF作为助熔剂、[001]向的定向籽晶、接近液面温度梯度为3～8℃/cm、5～20r/min的转速、0.05～0.1℃/h降温速率的生长工艺,使用直径为100mm的铂坩埚,成功地生长出100mm×40mm、光学均匀性为4.326×10-6的大尺寸高质量的β-BBO晶体.     

YVO4双折射晶体生长及完整性分析

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33mm×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,拉速:2～6mm/h,生长周期:24h,液面上8mm温度梯度2.875℃/mm.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.     

Nd:NaY(WO4)2晶体生长与开裂研究

本论文采用提拉法(CZ)生长了尺寸为φ15mm×20mm的Nd:NaY(WO4)2晶体,并从理论上讨论了温度梯度、提拉速度、晶体转速和晶体尺寸等工艺参数以及热应变等因素对晶体开裂的影响,给出了生长Nd:NaY(WO4)2晶体的最佳工艺参数.     

Cr,Yb,Ho:YAGG可调谐激光晶体生长及开裂研究

本文采用提拉法生长了Cr,Yb,Ho:YAGG可调谐激光晶体,并从理论上讨论了热应力、提拉速度、晶体转速和降温速率等因素对晶体开裂的影响,最后给出了掺铬、镱和钬钇铝镓石榴石激光晶体生长的最佳工艺条件:温度梯度为0.5℃/mm,提拉速度1～2mm/h,晶体转速20～40r/min,冷却速率不超过20℃/h.     

Nd∶NaY(WO_4)_2晶体生长与开裂研究

本论文采用提拉法 (CZ)生长了尺寸为1 5mm× 2 0mm的Nd :NaY(WO4) 2 晶体 ,并从理论上讨论了温度梯度、提拉速度、晶体转速和晶体尺寸等工艺参数以及热应变等因素对晶体开裂的影响 ,给出了生长Nd :NaY(WO4) 2 晶体的最佳工艺参数     

Nd∶NaY(WO4)2激光晶体生长

采用提拉法生长出了四方晶系白钨矿结构的Nd:NaY(WO4)2(简称Nd∶NYW)激光晶体,尺寸为20mm×30mm.通过TG-DTA差热分析得到晶体的熔点为1211℃,从XRD分析得到晶胞参数为a=b=0.5212nm ,c=1.1268nm ,晶胞体积V=0.3062nm3.讨论了Nd∶NYW晶体的生长工艺,给出了晶体生长的最佳工艺参数.通过比较Nd∶NaBi(WO4)2(简称Nd∶NBW)和Nd:NYW的XRD、红外光谱和拉曼光谱测试结果,认为二者结构基本相同,为四方晶系白钨矿结构、I(4)空间群.     

钐掺杂钨酸铅晶体的生长

为了用提拉法生长出质量优良的衫掺杂钨酸铅晶体,通过理论分析,实践论证,确定了生长晶体的工艺参数.温度梯度采用较成熟工艺,讨论晶体的生长速度和旋转速度.晶体生长速度为2 ～5mm/h;晶体旋转速度为35 ～50r/min;以45℃/h的速度降至室温,同时保持30r/min的旋转速度.得到了不同浓度衫掺杂的表观透明,无碎裂淡粉红色的钨酸铅晶体,且目前得到晶体的最大尺寸为φ25mm×40 mm.     

正钒酸钙晶体的生长及退火的研究

本文报道了Ca3(VO4)2晶体的生长,指出了由于局部区域温度过高引起原料分解产生气泡,光加热浮动熔区法不适合于生长这种晶体.采用了Czochralski法在合适的温场、提拉速度为3mm/h、转速10～20r/min等工艺条件下成功地长出了φ24×38mm的晶体.通过适当的温度梯度和退火条件解决了晶体生长和加工过程中的炸裂问题.     

β-Zn3BPO7晶体的提拉法生长研究

采用提拉法生长β-Zn3BPO7(简称ZBP)晶体.研究了生长工艺,用[210]方向的籽晶,获得了尺寸为35mm×20mm×10mm的单晶,该晶体无色透明,不开裂,呈现发育完好的{001}板面.通过设计特殊的温场以及在生长结束后采用适当的热条件有效地抑制了相变的发生.生长过程中靠近液面的温度梯度为30～60℃/cm,晶体转速为15～25r/min,提拉速度不大于1mm/h.ZBP晶体有宽的透光范围,它的紫外吸收边为240nm.ZBP晶体不潮解,其莫氏硬度为5Mohs.     

YAl3(BO3)4: Crystal growth and characterization

The growth and characterization of YAl₃(BO₃)₄ (YAB), a potential nonlinear optical crystal for the fourth harmonic generation of Nd:YAG laser, was reported. Using top-seeded solution growth method, a YAB crystal with the dimensions of 16×16×18 mm³ was obtained from B₂O₃–Li₂O flux system. The advantages of this flux system and the growth process were discussed in detail. The as-grown YAB crystal was verified by powder X-ray diffraction. The transparency spectra indicated that the cut-off edge of the as-grown YAB was 170 nm. The fourth harmonic generation of a frequency doubled Nd:YAG laser, from 532 to 266 nm, was carried out with a YAB crystal doubler for the first time. Output pulse power obtained was 2.4 mW at 266 nm and the conversion efficiency from 532 to 266 nm was about 15.6%.     

Crystal growth of NdAl3(BO3)4 from K2O/MoO3/Nd2O3/B2O3/KF flux

NdAl₃(BO₃)₄ single crystals were grown by the flux method and the TSSG technique using a K₂O/3MoO₃/B₂O₃/0.5Nd₂O₃/KF flux system. Light-violet clear crystals could be obtained. The effects of fluoride on the growth of NAB crystals were investigated. As the content of KF was gradually increased, the growth form of NAB was changed from the equant to the columnar and the primary crystalline region of NAB was shrinked. At the ratio of KF/K₂O = 0.75, NAB crystals could not be grown.     

Crystal structure of PbUO2(CH3COO)4(H2O)3

Single crystals of PbUO₂(CH₃COO)₄(H₂O)₃ have been investigated by X-ray diffraction (R = 0.029 for 3175 reflections). The structure of this compound is formed by [Pb(CH₃COO)(H₂O)₃]⁺ chains, which are oriented along the [100] axis and limited by one-core complexes [UO2(CH₃COO)₃]⁻. The coordination numbers of the Pb(II) and U(VI) atoms are 8, and the coordination polyhedron of uranium is a hexagonal bipyramid whose vertices contain oxygen atoms of three bidentate cyclic acetate groups and the uranyl group. Taking into account the different crystallographic roles of acetate ions, the crystal-chemical formula of [PbUO₂(CH₃COO)₄(H₂O)₃] chains can be written as AA′B ²¹ B ¹¹(B ⁰¹)₂ M ₃¹, where A = Pb; A′ = UO₂²⁺; M ¹ = H₂O; and B ²¹, B ¹¹, and B ⁰¹ are CH₃COO⁻ groups.     

Crystal growth and structure of MnGa2Te4

Single crystals of MnGa₂Te₄ were grown from the melt using the directional freezing technique. They crystallize in the monoclinic system, a=11.999(3), b=11.999(3), c=24.922(6) Å, β=104.01(2)°, Z=16 MnGa₂Te₄ units, space group C2/c. The structure was solved by direct methods and refined to R_w=0.035 for 791 observed reflections and to R_w=0.062 for 3067 independently measured reflections. Te atoms form an arrangement which is a superlattice of anion lattice of β-Cu₂HgI₄. On the contrary, the same model does not conform cation lattice, because 1/3 of metal atoms occupy positions displaced from tetrahedral sites.     

Crystal and molecular structures of trifluoromethyl derivatives of fullerene C86, C86(CF3)16 and C86(CF3)18

Trifluoromethyl derivatives of C₈₆ were obtained by the reaction of a mixture of higher fullerenes with trifluoromethyl iodide, followed by the HPLC separation of the products. The crystal and molecular structures of C₈₆(CF₃)₁₆ (two isomers) and C₈₆(CF₃)₁₈ were determined by single-crystal X-ray diffraction using synchrotron radiation. All compounds studied are derivatives of the cage isomer of C₈₆ no. 17 (C ₂). Original Russian Text ? S.I. Troyanov, N.B. Tamm, 2009, published in Kristallografiya, 2009, Vol. 54, No. 4, pp. 637–641.     

Crystal and molecular structures of trifluoromethyl derivatives of C82 fullerene: C82(CF3)12 and C82(CF3)18

Trifluoromethyl derivatives of C₈₂ have been obtained by the reaction between a higher fullerene mixture and trifluoromethyliodide, with subsequent isolation by high-performance liquid chromatography. The crystal and molecular structures of C₈₂(CF₃)₁₂ and C₈₂(CF₃)₁₈ have been determined by single crystal X-ray diffraction using synchrotron radiation. Both molecules are derivatives of C ₂-C₈₂ fullerene (isomer 3).     

Crystal growth of ferroelastic K2Cd2(SO4)3 and the K2SO4-CdSO4 phase diagram

Crystals of congruently melting K₂Cd₂(SO₄)₃ (having the langbeinite structure with a ferroelastic transition temperature of 156°C) were grown by the Bridgman and Czochralski techniques. The former yielded colorless crystals when using oxygen under pressure; the latter yielded tan crystals of slightly smaller unit cell volume and are assumed to be oxygen deficient. The ferroelastic transition was studied by thermal expansion measurements. Reexamination of the phase diagram showed the existence of a previously unreported phase K₆Cd(SO₄)₄ which is stable only between 520°C and the melting point of about 890°C.     

Nd^3＋：KGd（WO4）2激光晶体的研究

合成了一系列不同Nd     

La2CaB10O19晶体三倍频特性表征

本文研究了LCB晶体主平面内有效非线性光学系数最大的相位匹配方向上的三倍频特性,所用LCB晶体切割方向为:θ=48.7°,φ=90°,晶体尺寸:4×4×10 mm3.测量了它的角度带宽:θ角的角度带宽△θ×1为1.15mrad-cm;φ角的角度带宽△φ×1为86.15 mrad-em.还对其温度带宽进行了测定,结果为7.6℃-cm.利用这块晶体,得到了最高为31.8％的三倍频转换效率,而在相同实验条件下用LBO晶体(尺寸与LCB相同)得到的转换效率最高为38.4％.     

Crystal growth and characterization of K2B4O11H8

Single crystals of K₂B₄O₁₁H₈, a non-centrosymmetric borate material, have been prepared by slow evaporation of water solution at room temperature. The crystals were colorless and transparent with smooth faces. The single-crystal X-ray diffraction analysis showed that K₂B₄O₁₁H₈ crystallized in the orthorhombic space group P2₁2₁2₁ with a=6.8556(6) Å, b=11.7787(12) Å, c=12.8949(14) Å, Z=4, R₁=0.0188, and wR₂=0.0464. The powder X-ray diffractometry (PXRD), infrared spectrum, transmittance spectrum, TG–DTA curves and second harmonic generation properties of title compound have been determined.