Growth and characterization of ferroelectric Tb_2(MoO_4)_3 crystal

By using Tb407 and MoO3 as starting materials, ferroelectric Tb2（MoO4）3 crystal was grown by the Czochralski method. The as-grown crystal was pale green color, transparent and crack-free. X-ray powder diffraction （XRPD）, transmission spectrum, dielectric constant and polarization-electric field （P-E） hysteresis loop measurements were performed to characterize the crystal. The XRPD confirmed the as-grown crystal to be Tb2（MoO4）3. The transmission spectrum of the crystal showed that its transmittance in the entire visible and most near-infrared region was more than 70% except for an absorption peak around 486 nm. Obvious dielectric anomaly could be observed at low frequencies with increasing temperature through the dielectric constant measurement and the Curie temperature of Tb2（MoO4）3 crystal was determined to be 162.3℃ The unsaturated P-E hysteresis loops indicated that it was difficult for the ferroelectric domains in Tb2（MoO4）3 crystal to array regularly with repeated switching of the electric field.

Gd_2(MoO_4)_3∶Tb^(3+)荧光粉的固相合成与光谱性质

以MoO3、Gd2O3及Tb4O7为原料,以NH4HF2为助溶剂,在碳粉还原条件下制备了不同Tb3+掺杂浓度的Gd2(MoO4)荧光粉样品。采用X射线衍射(XRD)对样品的晶体结构进行了表征,发现掺杂浓度的改变未对产物的晶体结构产生影响,产物均为单一正交相Gd2(MoO4)3。对样品的激发、发射光谱及荧光衰减特性进行了测量和分析,结果表明:样品在200～300 nm范围内具有较强的源自于Tb3+的f-d跃迁及Mo-O电荷迁移跃迁吸收;在紫外光激发下观察到了Tb3+及MoO42-基团的本征发射。研究了发光强度、荧光寿命以及样品的发光色坐标与Tb3+浓度的关系,结果表明样品的发射光色纯度较差,该体系荧光粉与实际应用要求还有较大差距。

Eu^(3+)、Er^(3+)掺杂Tb_2(MoO_4)_3发光性能研究

通过高温固相法制备了Re_xTb_(2-x)Mo_3O_(12)(Re=Eu,Er; x=1%,3%,5%)材料.研究了不同Eu^(3+)、Er^(3+)掺杂浓度对Tb_2(MoO_4)_3发光性能的影响.X射线衍射结果表明:合成样品为纯相,Eu^(3+)、Er^(3+)的掺杂并不改变Tb_2(MoO_4)_3的晶体结构.激发光谱和发射光谱结果表明:随着Eu^(3+)掺杂浓度的增大,Tb_2(MoO_4)_3发光强度提高;随着Er^(3+)掺杂浓度的增大,样品发光强度先增强后减弱,存在浓度猝灭现象.本研究为开发新型发光材料提供了一定的参考.

Structure and Crystal Growth of Li_2Zn_2(MoO_4)_3

Single crystal of Li2Zn2（MoO4）3 has been grown from a flux of Li2MoO4 by the top-seeded solution-growth method, and its stnicture was refined by the Rietveld method. It belongs to the orthorhombic system, space group Pnma with a = 5.1114, b = 10.4906 and c = 17.6172A. Good agreement between the experimental and calculated profile （Rp = 6.69%, Rwp = 9.73% and Rexp = 6.58%） was reached.

Growth and Spectral Properties of Nd^(3+) Doped KLa(MoO_4)_2 Crystal

Nd^3＋ doped KLa（MoO4）2 single crystal with the size up to Ф25 × 40 mm^3 was grown by the Czochralski technique. The absorption and luminescence spectra of trivalent neodymium in KLa（MoO4）2 crystal were investigated at room temperature. The absorption and emission cross 10-20 sections are 3.02 ×10^-20 cm^2 at 808 nm and 20.01 × 10^-2 cm^2 at 1061 nm, respectively. The fluorescence lifetime is 164μs at room temperature.

Crystal Growth,Spectroscopic Properties and Energy Levels of Cr^(3+):Li_2Mg_2(MoO_4)_3

This paper reported the crystal growth and spectroscopy characters of Cr^3＋：Li2Mg2（MoO4）3. The refractive index of Cr^3＋：Li2Mg2（MoO4）3 crystal is 1.87 and the hardness is 270 I-IV. This crystal shows broadband absorption property with peak wavelength at about 495 and 699 nm. The absorption crosssection is 14.75 × 10^-20 cm^2 at 495 nm and 9.63 ×10^-20 cm^2 at 699 nm, respectively. The crystal field strength and energy levels of Cr^3＋ ion were calculated based on the spectroscopic data. The Cr^3＋：Li2Mg2（MoO4）3 crystal shows broadband emission extending from 750 to 1300 nm even excited at 10 K. The room temperature emission cross section is 72×10^-20 cm^2 at 926 nm. A discussion of the relation between the spectroscopic properties and crystal field parameters of Cr^3＋：Li2Mg2（MoO4）3 crystal was presented based on the solid state spectroscopytheory.

Synthesis,Characterization,X-ray Crystal Structure and Safener Activity of Chiral 2-(3-Methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl)-2-oxoethyl Acetate

The new title compound, chiral 2-（3-methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl）- 2-oxoethyl acetate, has been synthesized via reduction, cyclization and acylation reaction. The structure of the product has been confirmed by IR, 1H NMR, 13C NMR, LC-MS （ESI） and single-crystal X-ray diffraction. （R）-2-（3-methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl）-2-oxoethyl acetate crystallizes in monoclinic, space group P21/c with a = 11.867（2）, b = 8.4087（2）, c = 14.325（6） A^°, β = 117.59（2）°, Z = 4, V = 1266.9（6） A^°3, Dc = 1.307 g/cm^3, F（000） = 528, μ（MoKα） = 0.097 mm-1, R = 0.0453 and wR = 0.1237; （S）-2-（3-methyl-2,3-dihydrobenzo[b][1,4]oxazin-4-yl）-2-oxoethyl acetate belongs to the triclinic system, space group P with a = 8.2647（17）, b = 8.7034（17）, c = 9.5479（19） A^°, α = 105.33（3）, β = 100.95（3）, γ = 105.14（3）°, Z = 2, V = 614.1（2） A^°3, Dc = 1.348 g/cm^3, F（000） = 264, μ（MoKα） = 0.10 mm-1, R = 0.0613 and wR = 0.1037. Both of the molecules prefer to form crystal packing through C–H…O hydrogen bonds.

Synthesis and Crystal Structure of (SiCl_3)_2Fe(CO)_4

The compound （SiCl3）2Fe（CO）4 was synthesized and structurally characterized by X-ray single-crystal diffraction. It crystallizes in monoclinic, space group P2 1/n with α = 8.287（2）, b = 9.829（2）, c = 9.042（2） A, β = 96.19（3）°, V= 732.2（3） A^3, C4Cl6FeO4Si2, Mr = 436.77, Z = 2, Dc = 1.981 g/cm^3, F（000） = 424, μ（MoKα） = 2.282 mm^-1, the final R = 0.048 and wR = 0.164 for 1109 observed reflections （I 〉 2σ（I））. The crystal structure of （SiCl3）2Fe（CO）4 reveals that the Si（l）- Fe-Si（l）^a sequence is linear and perpendicular to the Fe（CO）4 cross-shaped plane.

Synthesis and Crystal Structure of Methyl 2-(Diphenylamino)-4-phenyl-1,3-thiazole-5-carboxylate

The title compound, methyl 2-（diphenylamino）-4-phenyl-1,3-thiazole-5-carboxylate, was synthesized and studied by single-crystal X-ray diffraction method. The structure of the product was confirmed by IR, 1H- and 13C-NMR spectroscopy and elemental analysis. These experimental studies were supported by quantum mechanical calculations. The structure was solved in monoclinic, space group P21/c with a = 9.573（3）, b = 19.533（7）, c = 9.876（3）, β = 92.35（4）°, V = 1845.2（10）3, T = 85（2） K, Z = 4, R = 0.040 and wR = 0.089 for 6424 observed reflections with I2σ（I）.

5-甲基-4-硝基-1H-吡唑-3-(2H)-酮及其含能离子化合物的合成与性能

以乙酰乙酸乙酯为原料合成了一种新型含能化合物——5-甲基-4-硝基-1H-吡唑-3-(2H)-酮(MNPO),总收率68%,通过复分解反应和中和反应,由MNPO与一系列高氮阳离子反应,制备出了相应的含能离子化合物。采用X-射线单晶衍射(XRD)、傅里叶变换红外光谱(FT-IR)、核磁共振(~1HNMR、^(13)CNMR)谱、元素分析等手段对其结构进行了表征。利用热重法(TG)-差示扫描量热法(DSC)测定了其热分解温度;运用Explo5v6.02软件对其爆轰性能进行计算。结果表明,MNPO晶体属于正交晶系,Pbca空间群,晶胞参数为a=0.71495(18)nm,b=1.1639(3)nm,c=1.3834(3)nm,V=1.1512(5)nm^3,Z=8。对密度范围为1.62~1.74g·cm^(-3)的MNPO的含能离子化合物,它们的热分解onset温度范围为181~272℃,理论爆速大于7000m·s^(-1),爆压大于15GPa;实测撞击及摩擦感度低,其中MNPO的铵盐的撞击感度为28J,摩擦感度为240N。

3-氨基-4,4'-联-1,2,4-三唑氢溴酸盐的合成与单晶结构

以3,3',5,5'-四叠氮基-4,4'-联-1,2,4-三唑(TABT)为起始原料,经(Ph)3P/H2O还原,再与HBr反应,合成了一种新型离子盐3-氨基-4,4'-联-1,2,4-三唑氢溴酸盐。采用X-射线单晶衍射,FT-IR,MS,1H NMR,13C NMR及元素分析表征了其结构。以甲醇为溶剂,通过溶剂缓慢挥发法培养并得到了3-氨基-4,4'-联-1,2,4-三唑氢溴酸盐的单晶(CCDC:1 516 993)。X-射线单晶衍射表明该晶体属于正交晶系,Pbca空间群,晶胞参数为a=1.547 41(13)nm,b=1.347 43(12)nm,c=1.573 31(14)nm,α=90°,β=90°,γ=90°,Z=16,DC=1.88 g·cm^(-3)。

Li_(1.3)Al_(0.3)Ti_(1.7)(PO_(4))_(3)原位包覆提升单晶三元LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)性能研究

高镍三元材料因其高容量、低成本而成为最具应用前景的正极材料,但其存在循环性能差、安全性不足等问题。使用溶胶-凝胶法,利用单晶高镍三元材料LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(S-NCM)表面残碱,对S-NCM进行原位Li_(1.3)Al_(0.3)Ti_(1.7)(PO_(4))_(3)(LATP)包覆,制备了具有小于10 nm厚度的均匀包覆层的LS-NCM正极材料。在电化学测试中,LS-NCM表现出明显提升的倍率和循环性能,这主要归因于:(1)LATP原位包覆S-NCM可显著降低其表面残碱量;(2)LATP原位包覆S-NCM可提高其表面稳定性,阻止副反应的发生,防止晶内裂纹产生;(3)因LATP具有高离子电导率,LATP原位包覆可减小S-NCM的极化。

KPO_3-MoO_3熔盐体系的拉曼光谱

对ＫＰＯ３ＭｏＯ３熔盐体系的拉曼光谱进行了分析和讨论，并辅以红外光谱及３１Ｐ核磁共振分析。ＫＰＯ３ＭｏＯ３熔盐体系拉曼光谱的主要贡献来自于ＰＯ４四面体基团和ＭｏＯ６八面体基团。根据结构与拉曼光谱的关系，推断Ｋ（ＭｏＯ２）ＰＯ４晶体的空间构型属Ｐｂａ２空间群。

2-羟基-4-甲基苯磺酸的合成工艺

2-羟基-4-甲基苯磺酸是合成内皮素拮抗剂UK-350,926的重要中间体。本文以4-氯-3-甲基苯酚为起始原料,经磺化和氢解两步反应得到目标化合物,并对其单晶结构进行了研究,其结构经1H NMR、13C NMR和X-ray单晶衍射确证。经优化后的工艺原料易得、操作简单、反应时间短且收率较高,适合工业化生产,反应总收率80.1%。

Growth and Optical Spectra of Tb^(3+)/Eu^(3+) Co-doped Cubic NaYF_4 Single Crystal for White Light Emitting Diode

High quality Tb^3＋/Eu^3＋ co-doped cubic NaYF 4 single crystal in the size of Φ1.0 cm×6.6 cm was grown by a modified Bridgman method using KF as assistant flux for NaF-YF 3 system under the condition of completely closed Pt crucible.A white light emission from the combination of the violet-blue,blue,green,orange,and red lights with chromaticity coordinates of x = 0.3107,y = 0.3274,correlated color temperature of T c = 6637 K,color rendering index of R a = 83,and color quality scale of Q a = 82 could be obtained from 1.51 mol%Tb^3＋ and 1.42 mol%Eu^3＋ co-doped cubic NaYF 4 single crystal when being excited by a 369 nm light.This indicates that Tb^3＋/Eu^3＋）co-doped cubic NaYF 4 single crystal has a potential application in white light emitting diode excited by ultraviolet light.

DFT calculation on p-xylene sensing mechanism of (C_(4)H_(9)NH_(3))_(2)PbI_(4) single crystal based on physisorption

P-xylene(p-C_(8)H_(10))is extremely harmful and dangerous to human health due to high toxicity and strong carcinogenicity.Exploring sensitive material to effectively detect p-xylene is of importance.In this paper,perovskite single crystal(C_(4)H_(9)NH_(3))_(2)PbI_(4) has been successfully synthesized via solution method.The obtained product was analyzed by single crystal X-ray diffraction.With the space group Pbca,orthorhombic(C_(4)H_(9)NH_(3))_(2)PbI_(4) layered perovskite structure consists of an extended two-dimensional network of corner-sharing PbI_(6) octahedron.Single layer perovskite sheets of distorted PbI_(6) octahedron alternated with protonated n-butylammonium cation bilayers,which offers many advantages and provides the possibility of forming a gas sensor device based on the change of resistances.Density functional theory(DFT)simulations regarding the adsorption energy revealed that this organicinorganic hybrid perovskite compound has excellent selectivity toward p-xylene compared with other gases including C_(2)H_(5)OH,C_(6)H_(6),CH_(2)Cl_(2),HCHO,CH_(3)COCH_(3) and C_(7)H_(8).The calculation of electron density,density of states and electron density difference showed the sensing mechanism of p-C_(8)H_(10) is mainly derived from physical adsorption-desorption in view of electron transfer.

4-(2,6-二氧杂-4,4-二溴甲基环己基)-N,N-二甲基苯胺的合成及结构表征

从季戊四醇出发,合成了二溴新戊二醇。并利用二溴新戊二醇与对二甲胺基苯甲醛进行羟醛缩合反应,合成得到4-(2,6-二氧杂-4,4-二溴甲基环己基)-N,N-二甲基苯胺,并对其合成条件进行了优化。利用核磁共振技术、单晶X-射线衍射法、质谱、红外吸收光谱技术对目标产物的结构进行了表征。

绿色发光材料NaLa(MoO_4)_2:Tb^(3+)的微波辅助溶胶-凝胶法制备及其性质

采用微波辅助溶胶-凝胶法制备了系列绿色发光粉NaLa31-x(MoO4)2:Tb+x(x=0.02,0.1,0.15)。用X射线粉末衍射仪和荧光分光光度计等分析和表征所合成样品的物相结构和发光性质。结果表明:所合成的NaLa(MoO4)2:Tb3+晶体结构与NaLa(MoO4)2相似,属四方晶系结构;样品的激发光谱为位于250~350 nm的1个宽带,最大激发峰位于300 nm处;发射光谱由一系列尖峰组成,最强的发射峰位于544 nm处,归属于Tb3+的5D4-7F5跃迁。NaLa(MoO4)2:Tb3+的发光强度随Tb3+掺杂浓度的增加逐渐加强,当Tb3+浓度为10 mol%时发光强度最大,而后随Tb3+浓度的增加而降低,发生浓度猝灭。根据Dexter能量共振理论,该浓度猝灭系Tb3+的电偶极-电偶极的相互作用所致。通过含氧酸根阴离子(SO2-4)的掺杂有效提高了NaLa(MoO4)2:Tb3+体系的发光亮度。

Polarized spectral analysis of Er^(3+) ions in Er^(3+)/Yb^(3+):LiLa(MoO_4)_2 crystal

Optical characteristics and upconversion dynamics of Er3+ in Er3+/Yb3+:LiLa(MoO4)2 crystals were investigated. The absorption spectra, fluorescence spectra and the fluorescence decay curves were analyzed at room temperature. The infrared emission at 1538 nm and visible emissions at 520–569 and 640–670 nm, corresponding to 2H11/2,4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+ ions, were simultaneously observed in Er3+/Yb3+:LiLa(MoO4)2 crystals under 976 nm excitation at room temperature. The maximal emiss...

P2_1m相掺钕钼酸钆晶体的结构

标题的晶体是采用提拉法得到的，单晶Ｘ射线结构分析表明：化合物分子式（Ｎｄ０．０２３Ｇｄ０．９７７）２（ＭｏＯ４）３ 晶体属于四方晶系，空间群为Ｐ４２１ｍ ， ａ＝ ｂ＝ ７．３５５６（１０） ，ｃ＝ １０．６８５（２）， Ｚ＝ ２，Ｄｃ＝ ４．５６３ｇ／ｃｍ ３，Ｍｒ ＝ １５８５．６４， Ｆ（０００）＝ ７００．００， μ（ＭｏＫα）＝ １４．５２７ｃｍ － １，Ｒ＝ ０．０４６３， ｗ Ｒ＝ ０．０９５３，衍射点数为６４５。Ｇｄ（Ｎｄ）原子为七配位，Ｍｏ 原子为四配位。