Structural and Spectral Studies of ZnKPO4 · 6H2O Crystals

Zinc Potassium Phosphate Hexahydrate (ZPPH) is analogous to naturally occurring struvite. ZPPH crystals are grown by slow evaporation technique. These crystals are characterised by x‐ray and infrared studies. Powder x‐ray pattern indicates the orthorhombic crystal structure analogous to struvite with unit cell parameters a = 5.964, b = 5.808 and c = 12.495 Å. Infrared spectrum is characteristic of H₂O and PO₄^3‐ radicals.     

X‐Ray Powder Diffraction,DTA and Vibrational Studies of CdNH4PO4.6H2O Crystals

Cadmium Ammonium Phosphate Hexahydrate (CAPH) is analogous to naturally occurring struvite. CAPH crystals are grown by slow evaporation technique. These crystals are characterised by X‐ray, TG‐DTA and Infra‐red studies. Powder X‐ray pattern indicates the orthorhombic crystal structure analogous to struvite. TG‐DTA analysis suggests loss of water of hydration (6H₂O) between 113 and 391°C. Later the substance melts and only Cd remains around 780 °C. Infra Red spectrum is characteristic of H₂O, PO₄^3‐ and NH₄⁺ radicals.     

Vibrational Studies of Gel Grown Ferroelectric RbHC4H4O6 and SrC4H4O6 4H2O Crystals

Single crystals of Rubidium Hydrogen Tartrate (RbHT) and Strontium Tartrate Tetrahydrate (SrTT) have been grown by a gel technique using a chemical reaction method. A controlled reaction has been employed between tartaric acid and feed solution (RbCl for RbHT and Sr(NO₃)₂) at room temperature. The laser Raman and FT-IR spectra of these crystals are recorded in the frequency range 100 - 4000 cm^-1. The presence of tartrate ion, monohydrogen tartrate ion, water molecules and external mode vibrational frequencies are identified and discused. The doublet and broad nature of tartrate ion vibrational frequencies have also been observed and analysed.     

掺杂晶体SrLaAlO4:Cr3+局域结构的研究

采用半自洽场 (semi-SCF) d轨道波函数模型和点电荷模型,利用高阶微扰公式,在晶体掺杂过渡金属离子后其结构对称性不会被破坏的条件下,由d-d跃迁光谱和EPR谱,确定SrLaAlO4: Cr3+晶体的局域结构.计算发现,掺入Cr3+后,晶体的键长为:R′⊥=0.1922nm, R′∥=0.2197nm.所得计算结果与实验值吻合得很好.     

Spectral Studies on VO2+ doped MPPH Crystals

Magnesium Potassium Phosphate Hexahydrate (MPPH), is analogous to the bio‐mineral struvite. Vanadyl doped MPPH crystals are grown by slow evaporation technique. EPR and optical absorption studies are carried out at room and liquid nitrogen temperatures. Spin‐Hamiltonian, crystal field and bonding parameters are evaluated.     

Cr4+在Al2O3透明陶瓷中的发光行为

采用传统无压烧结工艺制备出透明性良好的掺Cr的Al2O3透明陶瓷;测定了其吸收光谱和荧光光谱,发现在Al2O3六配位的八面体结构中,除了有Cr3+离子的特征吸收峰外,由于有Mg2+的电荷补偿作用,也有Cr4+离子,Cr4+的荧光发射峰位于1223nm附近,与Cr4+在四面体中的发光行为一致.但其荧光发射峰较窄,半高宽△λ仅为37nm.     

Nd~(3 )∶Sr_3Ga_2Ge_4O_(14)晶体的生长及吸收光谱

采用坩埚下降法生长了Nd3 掺杂浓度分别为 15 %、8%和 2 .5 %原子分数的Sr3 Ga2 Ge4O14 晶体 ,所得晶体最大尺寸为2 6mm× 15mm。Nd3 掺杂Sr3 Ga2 Ge4O14 晶体的特征吸收峰波长为 80 6nm ,与Nd3 离子在YAG中的特征吸收峰相比 ,向短波方向发生了微小的偏离。这是Sr3 Ga2 Ge4O14 晶格中Ga3 和Ge4 的统计分布所致。Nd3 ∶SGG晶体的这些特性将有助于泵浦效率的提高和泵浦阈值的降低 ,因此Nd3 ∶SGG晶体有望成为一种新型的LD泵浦固体激光材料。     

Structural features of a new [Fe(nicotinamide)2(H2O)4]·[Fe(H2O)6]·(SO4)2·2H2O complex

A new nicotinamide complex of Fe(II) cation was prepared by reaction between ferrous sulfate and nicotinamide in aqueous solution. The complex was characterized on the basis of elemental analysis, FT IR and UV–VIS spectroscopy, electrochemistry (cyclic voltammetry) and X–ray crystallography. The complex consists of the molecular composition of [Fe(nicotinamide)₂(H₂O)₄]· [Fe(H₂O)₆]·(SO₄)₂·2H₂O. The complex crystallizes in the monoclinic space group P 2₁/c [a = 12.862(3), b = 7.110(3), c = 16.382(3) Å; β = 95.79(2)°]. It has been proven that nicotinamide is coordinated to Fe(II) through the nitrogen atom of its heterocyclic ring. © 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim     

晶体(NH4)2C4H4O6:VO2+的EPR参量及局域结构的研究

采用叠加模型和双旋-轨耦合参量模型,建立了结构参数与EPR参量之间的定量关系;较好地解释了[VO(H2O)5]2+络离子的局域结构和EPR参量;研究结果发现,(NH4)2C4H4O6:VO2+晶体中络离子[VO(H2O)5]2+的键长为R//≈0.130nm,R⊥≈0.195nm;在(NH4)2C4H4O6:VO2+晶体中,局域结构沿C4轴方向呈压缩的八面体结构;所得EPR参量的理论计算与实验测量数据符合很好.     

Cao.28Ba0.72Nb2O6单晶的光学常数及吸收特性

山大晶体所采用提拉法生长出新晶体铌酸钙钡.本文通过分光光度计和椭偏光谱仪分别测得室温下铌酸钙钡的透射率和折射率随波长的变化关系.透射率光谱显示该晶体在波长大于380nm的可见光谱区是透明的.色散关系表明此材料的双折射较大,在短波区域寻常光及非常光的折射率之差约为0.12.此外,由透射率曲线计算了可见光范围内铌酸钙钡的吸收系数.从而得到吸收系数的平方根与光子能量的函数关系曲线.通过对该曲线的研究,发现铌酸钙钡晶体吸收边以下对应的跃迁为间接跃迁,计算出间接跃迁的禁带宽度Eg以及声子能量Ep.     

电子辐照对MgAl2O4尖晶石光学性质的影响

本文利用1.7 MeV电子辐照MgAl2O4尖晶石后,通过吸收谱测量表明,被电子辐照的尖晶石可产生大量的F型色心缺陷, 而且电子的辐照剂量明显地影响尖晶石的光谱特性.随着电子辐照剂量增加, F型色心缺陷的浓度增大;椭偏光谱分析得到的光学常数谱随电子辐照剂量的变化而改变.我们对上述现象进行了合理的分析.     

钕镱共掺四钼酸钆钡晶体的生长与光谱性能研究

通过单晶提拉法制备了钕镱共掺四钼酸钆钡(BaNd2x Yb2yGd2(1-x-y)(MoO4)4,x=0.1,0.05,0.01,y=0.1)晶体,研究了其热学性能和光谱性能.结果表明,钕镱共掺四钼酸钆钡晶体的熔点为1070.3℃,采用Judd-Ofelt理论计算得到了5at; Nd3+/10at; Yb3+∶BaGd2(MoO4)4晶体中Nd3+的强度参数Ω2.4.6,4F3/2能级的自发辐射几率、跃迁的荧光分支比以及辐射寿命.通过研究该晶体的吸收光谱、荧光光谱以及Yb3+的2 F5/2能级的荧光寿命,分析了Nd3+对Yb3+的敏化作用,对比发现掺杂浓度为1 at; Nd3+/10at; Yb3+的BaGd2(MoO4)4在1013 nm处的荧光寿命最长.     

Characterisation of the Six-coordinated Octahedral Site in Cd(C4H2O4) · 2H2O Crystals

Optical absorption spectra of Co(II) and Ni(II) doped cadmium maleate dihydrate (CMDH) are recorded at room temperature and liquid nitrogen temperature. The UV–VIS–NIR spectra are characteristic of the transition metal ions in solids. The results and analyses of the spectra indicate near octahedral site symmetry for cobalt ion and trigonally distorted octahedral site symmetry for nickel ion. The following crystal field parameters are derived. The IR spectra are characteristic of the host lattice CMDH.     

Equilibrium coefficients of co‐crystallization of M2+ ions with MgSeO4·6H2O and their dependences on various physicochemical factors

Equilibrium co‐crystallization coefficients of low amounts of M²⁺ions (M²⁺ = {Ni²⁺, Cu²⁺, Co²⁺, Zn²⁺, Mn²⁺, Cd²⁺}) with MgSeO₄·6H₂O at 25 °C have been determined. Their values are comprised in the range: 0.058 (for Cd) < k_eq < 1.57 (for Co) and depend on some physicochemical and crystal chemical properties of both: co‐crystallizing salts (MSeO₄·nH₂O) and co‐crystallizing ions (M²⁺). These dependences are sometimes such strong, that they make it possible to derive simple formulae permitting estimation of k_eq coefficients at average error not exceeding 17%. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Recharging Processes of Chromium Ions in Cr:SrGdGa3O7 and Cr:SrLaGa3O7 Single Crystals

Growth and recharging processes of chromium ions in SrGdGa₃O₇ and SrLaGa₃O₇ single crystals incorporated during growth or doping by diffusion (only for SrLaGa₃O₇ crystal) were analyzed. The annealing at 1000°C in air and ionizing with gamma rays (doses from 103 to 105 Gy) and protons (1014 cm^-2 only for SrGdGa₃O₇ crystal) were performed. Different kinds of chromium ions valency, from two to four, were found. Electron spin resonance measurements in the temperature range 5-300K with the use of Brucker spectrometer were also done.     

Preparation and Properties of a Novel Nonlinear Optical Crystal: MnHg(SCN)4(H2O)2.2(C3H6CONCH3)

In this article, diaquatetrakis (thiocyanato) manganese(II) mercury(II)‐N‐methyl‐2‐pyrrolidone, MnHg(SCN)₄(H2O)₂.2(C₃H₆CONCH₃), (abbreviated as MMTWMP), a new organometallic nonlinear optical crystal material is reported. The structure, optical and thermal characterizations were determined by elemental analysis, infrared and Raman spectroscopy, X‐ray powder diffraction, thermogravimetric analysis, differential scanning calorimetry, special heat, SHG measurements and UV/Vis/NIR optical transmission spectra. It belongs to the tetragonal crystallographic system, with cell parameters: a = 12.1294, c = 8.2238Å, V = 1211.27ų. Single crystals with dimensions up to 8 × 7 × 5 mm³ have been obtained. The morphology of the crystals was indexed. The MMTWMP crystal exhibits good physicochemical stability at normal temperature and pressure. Its UV transparency cutoff is 360 nm, which is shifted to the violet by 13 nm, as compared with MnHg(SCN)₄ (MMTC); the optical transmission is 44.82% at 404 nm, which is by 17.46% higher than that of MMTC.     

Er3+掺杂钨酸铅晶体的发光和光谱特征

本试验测试了Er3 掺杂钨酸铅晶体(PbWO4:Er3 )的吸收光谱,依据J-O理论,首次计算报道了光谱项特征:J-O强度参数、量子荧光效率、荧光分支比等,Ω2=3.75×10-20cm2,Ω4=0.67×10-20cm2,Ω6=0.41×10-20cm2。计算证实,PWO:Er3 中几乎有80%的激发能量非辐射跃迁转移致4I13/2能级,4I13/2的计算寿命是5200μs,J-O计算显示,在PWO中产生4I13/2→4I15/2和发射1.53μm.有高的几率。讨论了不同浓度Er3 掺杂对于吸收系数和PbWO4晶体光学吸收边的影响,讨论了Er3 掺杂PbWO4晶体的光致发光和X射线激发发光光谱,PbWO4:Er3 晶体中存在着从PbWO4基质到Er3 离子的能量传递,发光光谱的分析表明,这种能量传递是共振能量传递。     

Ca(H2PO4)2-H3PO4-K2SO4体系中石膏晶型及形貌调控

为将Ca(H₂PO₄)₂制备KH₂PO₄过程中的石膏资源化利用,以H₃PO₄与CaCO₃反应制备Ca(H₂PO₄)₂溶液,并与K₂SO₄溶液反应,进行Ca(H₂PO₄)₂-H₃PO₄-K₂SO₄体系中石膏晶型和形貌调控研究。结果表明:通过改变反应时间、反应温度、SO^2-₄过量系数和CaO含量等参数可对Ca(H₂PO₄)₂-H₃PO₄-K₂SO₄体系中石膏晶型和形貌进行调控,制得短柱状α-CaSO₄·0.5H₂O。体系在温度高于95 ℃和CaO含量为3.0%~5.0%(质量分数,下同)时形成α-CaSO₄·0.5H₂O,在CaO含量为5.5%主要形成CaSO₄·2H₂O;反应时间长于20 min和SO^2-₄过量系数大于1.4将形成K₂SO₄(CaSO₄)₅·H₂O,导致石膏晶体表面缺陷增加。本实验条件下,适宜反应条件为:反应时间10 min、反应温度95 ℃、SO^2-₄过量系数1.2和CaO含量5.0%,此条件下可制得长度42~70 μm、直径13~24 μm的短柱状α-CaSO₄·0.5H₂O,其抗折和抗压强度分别可达5.61 MPa和33.74 MPa,滤液中钾收率和脱钙率分别可达94.23%和83.80%。     

水热法生长非线性光学晶体K4Gd2(CO3)3F4

采用水热法,探索了 K4Gd2(CO3)3F4晶体的析晶条件,诸如生长原料及配比、生长温度、生长周期等,并成功生长了毫米级的透明单晶.对生长的晶体进行了XRD、UV-Vis-NIR、SHG等测试,结果表明,K4Gd2( CO3)3F4晶体在380～2000 nm波段的透过率超过80;,紫外吸收截止边低于200nm;其二阶非线性光学效应约为KDP的3.5倍.     

Crystal structure and vibrational spectra of hydrazinium(2+) aquatetrafluoroindate(III), N2H6(InF4H2O)2

The crystal structure of hydrazinium(2+) aquatetrafluoroindate(III), N₂H₆(InF₄H₂O)₂, has been determined by X-ray diffraction. The compound crystallizes in the triclinic space group (C _i ¹) with a = 6.759(2) Å, b = 6.228(1) Å, c = 5.7854(7) Å, = 80.28(2)°, = 88.79(1)°, = 69.96(2)°, V = 225.3(1) ų, and Z = 1. The structure comprises hydrazinium(2+) cations and InF₂F_4/2O^– anions in which In appears to be seven-coordinated in the form of a pentagonal bipyramid by four bridging fluorine atoms, two terminal fluorine atoms, and one oxygen atom. Pentagonal bipyramids are interconnected and form chains along a axis. Bands in vibrational spectra were assigned to the vibrations in N₂H₆ ²⁺ cations and anionic InF₂F_4/2O^– entities. The rather intensive band appearing at 1042 cm^–1 in Raman spectrum, which is absent from infrared, is characteristic of the N₂H₆ ²⁺ cation, in line with the predictions of the unit-cell group analysis for the studied system.