三维(C2H7N4S)+·(C7H5O4)——超分子氢键网格的构筑

利用脒基硫脲和3,5-二羟基苯甲酸制备出了一种新型的加合物(C2H7N4S)+·(C7H5O4)-,用X射线单晶衍射试验方法测定其晶体结构.结果表明,晶体属单斜晶系,P21/n空间群,其中a=0.72303(1)nm,b=1.42970(3) nm,c=1.07991(2)nm,β=91.591(2)°,Z=4,R1=0.0303, wR=0.0823(I>2σ(I)).在标题化合物的晶体结构中,3,5-二羟基苯甲酸通过羧基和羟基的O-H…O氢键头尾相连形成了沿b轴无限延伸的"Z"型链,脒基硫脲通过氢键的缔合和静电相互作用连接3,5-二羟基苯甲酸的"Z"型链构成了3D超分子氢键网络结构.     

Sb2O3掺杂BiFeO3-BaTiO3压电陶瓷的结构及电性能研究

采用传统固相烧结法合成了0.7BiFeO₃-0.3BaTiO₃+x%Sb₂O₃(质量分数)陶瓷(BFO-BTO+xSb, x=0.00~0.20),研究了Sb₂O₃掺杂对BFO-BTO陶瓷的晶相结构、介电、导电以及压电和铁电性能的影响,并对影响机理进行探讨。结果表明:Sb掺杂导致陶瓷的晶体结构由伪立方相向菱形相转化。Sb的B位取代增加了BFO-BTO+xSb陶瓷的铁电弛豫性,降低高温损耗,并使居里温度T_c有所降低。导电特性的研究表明,Sb掺杂改变了$V_O^×$和Fe²⁺的浓度,降低了电导率,但没有改变陶瓷的导电机制,其主要载流子是氧空位。Sb掺杂量x=0.05时,BFO-BTO+xSb陶瓷表现出最佳的综合电性能:d₃₃=213 pC/N,k_p=28.8%,Q_m=38,T_c=520 ℃,P_r =24.7 μC/cm²。     

配合物2[NiL2(H2O)2]·DMF的合成、晶体结构与荧光性质的研究

以喹啉-2-甲酸与醋酸镍为原料,采用水热法合成配合物2[NiL₂(H₂O)₂]·DMF(L=喹啉-2-甲酸根离子,DMF=N,N-二甲基甲酰胺),并通过X-射线单晶衍射、X-射线粉末衍射、元素分析、红外光谱、热重分析、荧光光谱对其进行结构解析和性质表征.晶体结构解析表明:标题配合物晶体属于正交晶系,空间群为Pna21;其晶胞参数是:a=2.06753(6)nm,b=0.82571(3)nm,c=2.34776(7)nm,V=4.0081(2)nm³,Z=4,Mr=951.210,Dc=1.576 g/cm³.标题配合物为单核配合物,配位单元之间通过分子间氢键和π-π堆积作用,把配合物扩展为三维超分子结构.荧光光谱分析表明配体和标题配合物均有良好的荧光性,且配合物荧光性优于配体.     

草酸配体修饰的锆取代型硅钨-氧簇合物的合成、结构和电化学性质研究

通过水热反应,成功合成了一个草酸配体修饰的四核锆取代的夹心型硅钨-氧簇合物H₁₂Na₂[Zr₄(μ₃-O)₂(μ₂-OH)₂(Ox)₂(α-SiW₁₀O₃₇)₂]·22H₂O (Ox=oxalic acid)。该夹心型硅钨-氧簇是由两个{α-SiW₁₀O₃₇}簇块通过一个{Zr₄(μ₃-O)₂(μ₂-OH)₂(Ox)₂}簇连接构成的。通过X-射线单晶衍射、IR、TG以及元素分析对该簇合物进行表征。晶体结构分析表明: 该簇合物结晶于单斜晶系,P2₁/c空间群,a=2.132 2 (6) nm, b=1.271 6 (4) nm, c=2.223 1 (7) nm, β=110.933(4)°,V=5.629 9(3) nm³,Z=2,R₁=0.061 5,wR₂=0.164 4。电化学和电催化性质研究表明标题簇合物对NO^-₂的还原有很好的电催化效果。     

Bi4Ge3O12:Er3+晶体中的高阶混合效应对EPR g因子的影响

通过对角化364×364完全能量矩阵的理论方法,对掺杂在Bi₄Ge₃O₁₂晶体中的Er³⁺的Stark能级和EPR参数进行了研究,同时,定量分析了高阶晶体场混合效应和J-J混合效应对EPR g因子的影响。研究结果表明:对Er³⁺来说,最主要的J-J混合效应来源于多重态谱项²K_15/2,其对EPR g因子的贡献约占2.5%,而最主要的高阶晶体场混合效应来源于第一激发多重态⁴I_13/2和基态多重态⁴I_15/2之间的晶体场混合,其对各向异性g因子中g_⊥的贡献大致是g_//的两倍(即g_⊥约占 0.21%,g_//约占0.092%),其他更高阶的晶体场混合和J-J混合效应可以忽略不计。因此,对于Er³⁺掺杂的络合物系统来说,只考虑基态多重态⁴I_15/2对EPR g因子的贡献应该是一个很好的近似。     

一例含阴离子水簇的钴配合物的合成、结构及理论研究

金属配合物中的水簇研究为研究宏观意义上的水以及与蛋白质分子有关的水分子提供了有效途径。本文合成了一个含有阴离子水簇的带状超分子配合物[Co(2,2-bipy)₂(N₃)₂](N₃)_0.5Cl_0.5·2H₂O(1,2, 2-bipy=2, 2-联吡啶)。单晶结构解析表明,配合物属于三斜晶系,P-1空间群,晶胞参数为:a=0.822 54(7) nm,b=1.175 58(9) nm,c=1.237 06(10) nm,α=91.379 0(10)°,β=92.151 0(10)°,γ=108.119 0(10)°,V=1.135 27(16) nm³,由一个单核[Co(2,2-bipy)₂(N₃)₂]⁺配合物阳离子、两个非配位水分子、0.5个游离的叠氮离子和0.5个氯离子组成,叠氮离子和氯离子位置无序,占有率各为50%。两个客体水分子通过强烈的分子间氢键作用形成了环状水四聚体,且与无序的N^-₃和Cl^-通过氢键作用形成了一个[(H₂O)₄(N₃)Cl]^2- 阴离子水簇。此外,本文基于密度泛函理论(DFT)对配合物[Co(2,2-bipy)₂(N₃)₂]⁺阳离子进行了量子化学计算,分析了其单点能和原子电荷,并计算了中心金属离子的氧化态,计算结果与实验相吻合。     

一例铽簇合物的合成、晶体结构与磁性

本文以2, 6-二甲氧基苯酚和硝酸铽为原料，成功合成了一例新型九核铽簇合物{Tb₉(L)₄(μ₄-OH)₂(μ₃-OH)₈(μ₂-OCH₃)₄(NO₃)₈(H₂O)₈}(OH)·2H₂O(1),其中HL为2, 6-二甲氧基苯酚。通过X射线衍射、元素分析、红外光谱、热重和磁性测试对该簇合物进行表征。X射线单晶衍射分析结果表明，簇合物属于正交晶系，空间群为I222,晶胞参数为a=1.532 8(3) nm,b=1.796 9(4) nm,c=1.863 5(4) nm,α=β=γ=90°,V=5.132 6(19) nm³。簇合物中九个金属中心由μ₄-OH和μ₃-OH相互连接，形成的骨架呈现出有趣的沙漏状拓扑结构，其中，中...     

8英寸氟化钙单晶生长

氟化钙(CaF₂)晶体是一种性能优良的光学晶体材料。本研究用坩埚下降法生长了8英寸(20.32 cm)氟化钙单晶,晶体外观完整,无开裂及散射等宏观缺陷。定向切割后得到ϕ40 mm×6 mm的透明圆柱形晶体毛坯,对毛坯样品进行二次退火处理后进行研磨抛光得到最终样品。对该系列样品进行紫外可见透过率、光学均匀性、应力双折射等测试。结果显示在200 nm波长处晶体透过率达到90%,平均应力双折射小于0.5 nm/cm,光学均匀性达到2.63×10^-6。     

MoS2/SnS异质结太阳能电池的模拟研究

硫化亚锡(SnS)是一种Ⅳ-Ⅵ族层状化合物半导体材料,其禁带宽度与太阳能电池最佳带隙1.5 eV非常接近,并且在可见光范围内光的吸收系数很大(α>10⁴ cm^-1),因此SnS是一种很有应用前景的材料。本文利用太阳能电池模拟软件wxAMPS模拟了MoS₂/SnS异质结太阳能电池,主要研究SnS吸收层的厚度、掺杂浓度和缺陷态等因素对太阳能电池性能的影响。研究发现:SnS吸收层最佳厚度为2 μm,最佳掺杂浓度为1.0×10¹⁵ cm^-3;同时高斯缺陷态浓度超过1.0×10¹⁵ cm^-3时,电池各项性能参数随着浓度的增加而减小,而带尾缺陷态超过1.0×10¹⁹ cm^-3·eV^-1时,电池性能才开始下降;其中界面缺陷态对太阳能电池影响比较严重,界面缺陷态浓度超过1.0×10¹² cm^-2时,开路电压、短路电流、填充因子和转换效率迅速下降。另外,通过模拟获得的转换效率高达24.87%,开路电压为0.88 V,短路电流为33.4 mA/cm²。由此可知,MoS₂/SnS异质结太阳能电池是一种很有发展潜力的光伏器件结构。     

4-硝基氮氧化吡啶-2-甲酸构筑的镧、镨配合物的合成、晶体结构及荧光性质

选择刚性有机化合物4-硝基氮氧化吡啶-2-甲酸(POA)作为配体，与稀土金属La(III)、Pr(III)反应，合成了2个一维配位聚合物。X射线单晶衍射结果表明：配合物1的分子式为{[La(POA)₃H₂O]·CH₃OH}_n,属于单斜晶系，空间群是P2₁/c。该晶胞参数分别为a=1.756 8 nm,b=0.663 6 nm,c=2.048 6 nm,α=90°,β=96.96°,γ=90°,V=2.370 7 nm³,M_r=738.28。配合物2的分子式为{[Pr(POA)₃H₂O]·H₂O}_n,属于单斜晶系，空间群是P2₁/c。该晶胞参数分别为a=1.757 8 nm,b=0.656 9 nm,c=2.046 7 nm,α=90°,β=97.20°,γ=90°,V=2.344 8 nm³,M_...     

Growth and spectral properties of Nd:LaVO4 crystal

This paper reports the growth and spectral properties of 3.5 at% Nd³⁺:LaVO₄ crystal with diameter of 20×15 mm² which has been grown by the Czochralski method. The spectral parameters were calculated based on Judd–Ofelt theory. The intensity parameters Ω_λ are: Ω₂=2.102×10⁻²⁰ cm², Ω₄=3.871×10⁻²⁰ cm², Ω₆=3.235×10⁻²⁰ cm². The radiative lifetime τ_r is 209 μs and calculated fluorescence branch ratios are: β₁(0.88μm)=45.2, β₂(1.06μm)=46.7, β₃(1.34μm)=8.1. The measured fluorescence lifetime τ_f is 137 μm and the quantum efficiency η is 65.6%. The absorption band at 808 nm wavelength has an FWHM of 20 nm. The absorption and emission cross sections are 3×10⁻²⁰ and 6.13×10⁻²⁰ cm², respectively.     

Properties of ZrO2---Al2O3 composite powders prepared from Zr---Al metallo-organic compounds

Zr---Al metallo-organic compounds (zircoaluminates), having (CH₂)₄COOH, (CH₂)₁₂CH₃ and (CH₂)₂NH₂ as the organofunctional groups, were treated preliminary by (1) spray-drying, (2) gelation of addition of 10% NH₄OH aqueous solution followed by spray-drying and (3) rotary evaporation under a reduced pressure. After the treatment they were heated in air to prepare ZrO₂---Al₂O₃ composite powders. The IR and DTA profiles for the treated compounds indicated that the procedures modified the structures for the zircoaluminates. The stability of tetragonal ZrO₂ for the ZrO₂---Al₂O₃ composite powder were dependent on the modification in the structure for the zircoaluminates. Balloon shaped particles, 0.5–2 μm in diameter, were obtained through procedure (1) and spherical particles, 1–4 μm in diameter, through (2). Tetragonal ZrO₂ grains, 0.1–0.2 μm in diameter, were dispersed in the particles when heated at 1400°C.     

GaN-MOVPE气相自由基反应的量子化学研究

利用量子化学的密度泛函理论(DFT),对TMG/NH₃/H₂体系中自由基参与的金属有机气相外延(MOVPE)反应进行计算分析,特别针对H、NH₂自由基对Ga(CH₃)₃(简称TMG)热解路径、氢解路径以及加合路径的影响进行研究。通过计算不同反应路径的吉布斯自由能差ΔG和能垒ΔG^*/RT,确定了自由基参与的气相反应在不同温度下不同的反应路径。研究发现:当T<683 K时,TMG与NH₃反应生成加合物TMG:NH₃。当T>683 K时,TMG:NH₃重新分解为TMG和NH₃。TMG在MOVPE温度下很难直接热解,在H自由基作用下则易热解产生Ga(CH₃)₂(简称DMG)、GaCH₃(简称MMG)和Ga原子。当T<800 K时,TMG与NH₃的氨基反应速率大于自由基参与的热解反应,故氨基反应占主导;当T>800 K时,自由基参与的TMG热解反应速率大于氨基反应,故热解反应占主导。氢解反应由于能垒很高,因此可忽略。TMG及其热解产物与NH₂自由基反应很容易产生氨基物。氨基物DMGNH₂可以与H自由基继续反应,最终生成表面反应前体GaNH₂。     

The preparation and characterization of silica gels doped with copper complexes

Silica gels doped with [Cu(C₅H₅N)₄]²⁺ (C₅H₅N = Py), CuCl₂-HOCH₂CH₂OH and Cu(CH₃COO)₂-NH₂(CH₂)₃Si-(OC₂H₅)₃ (CH₃COO = OAc, C₂H₅ = Et) have been prepared and examined by X-ray diffraction, electron spin resonance, transmission electron microscopy (TEM), thermal gravimetric analysis and Fourier transform infrared spectroscopy. Different dopants have different interactions with the silica alcogels depending on the chemistry of the dopants: [Cu(Py)₄]²⁺ forms chemical bonds with the hydroxyl oxygens on the surface of the silica matrix; in Cu(OAc)₂-NH₂(CH₂)₃Si(OEt)₃-doped alcogels, the siloamine enters into the sol-gel reaction and Cu(OAc)₂ coordinates to the -NH₂(CH₂)₃ ligand of the precursor. However, there is no evidence for bond formation between copper and the hydroxyl groups on the silica surface in the CuCl₂-HOCH₂CH₂OH-doped alcogels. The TEM images show a homogeneous and uniform distribution of copper particles on the reduced CuCl₂-HOCH₂CH₂OH- and Cu(OAc)₂-NH₂(CH₂)₃Si(OEt)₃-doped xerogel surface. The type of nitrogen adsorption isotherms of doped silica xerogels are unaffected by the dopant concentration. However, their surface areas do depend on the level of dopant. The microstructure of the silica matrix is primarily determined by the pH of the initial reactants, at least in the [Cu(Py)₄]²⁺-doped case.     

Porous glass-ceramics composed of a titanium phosphate crystal skeleton: A review

Bulk microporous glass-ceramics with a skeleton of two types of functional titanium phosphate crystal were prepared by controlled crystallization of RTi₂(PO₄)₃ (

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glasses, and chemical treatment. One crystal is a NASICON-type with a three-dimensional network structure of TiO₆ and PO₄ while the other is a zirconium phosphate-type crystal Ti(HPO₄)₂ · 2H₂O with a two-dimensional layered structure. The mean pore diameter and porosity of 30–60 nm and 40–60 vol.% were achieved. Porous CaTi₄(PO₄)₆ glass-ceramics have excellent properties as supports for immobilization of enzymes, humidity sensors and porous LiTi₂(PO₄)₃ glass-ceramics as ion exchange media. Conspicuous bacteriostatic activities were found for the partially Ag-exchanged porous LiTi₂(PO₄)₃ and Li_1.4Ti_1.6Al_0.4(PO₄)₃. Integrated microporous glass-ceramics with skeletons of LiTi₂(PO₄)₃ (LTP) and Ti(HPO₄)₂ · 2H₂O (TP) crystals were synthesized utilizing a novel discovery that LTP is transformed into TP in acid solution.     

一种具有荧光性质的三维Zn(Ⅱ)金属-有机框架

以1,3,5-苯三甲酸(H₃BTC)为配体,与Zn(Ⅱ)离子在溶剂热条件下反应制备了配合物{[Zn(BTC)_2/3]·[HCON(CH₃)₂]·[C₂H₅OH]}_n(1)。通过单晶X射线衍射分析(SXRD)、红外光谱(FT-IR)、热重分析(TGA)、粉末X射线衍射分析(PXRD)和荧光光谱对配合物1进行表征。单晶X射线衍射分析表明,配合物1属于单斜晶系P2₁/n空间群。在配合物1中Zn(Ⅱ)离子通过羧基上的氧原子与BTC^3-离子配位,形成了具有孔道的三维Zn(Ⅱ)金属有机框架(MOF)结构。并且通过分子间氢键相互作用,将乙醇和N,N'-二甲基甲酰胺(DMF)分子封装进平行四边形的孔道中。室温下的荧光光谱分析表明,当激发波长为297 nm时,配合物1在601 nm处具有最强的发射峰。     

Novel single source precursors for MOCVD of AlN, GaN and InN

The MOCVD of AlN, GaN and InN thin films using the novel single source precursors (N₃)₂Ga[(CH₂)₃NMe₂] (1), (N₃)In[(CH₂)₃NMe₂]₂ (2), (N₃)Al[(CH₂)₃NMe₂]₂ (3) and (N₃)AlMe₂(H₂N^tBu) (4) is reported. The compounds are non-pyrophoric. Compound 3 is air stable. No additional N-sources were used for the growth of the nitrides. We achieved epitaxial (AlN, GaN) or polycrystalline (InN) growth at least 200°C below the decomposition temperature of the respective nitride. Some aspects of the reactivity of the precursors with ammonia and the resulting influence on the deposition process were investigated.     

Mechanochemical–hydrothermal synthesis of hydroxyapatite from nonionic surfactant emulsion precursors

Nanocrystalline hydroxyapatite [HA, Ca₁₀(PO₄)₆(OH)₂] powders were synthesized by the mechanochemical–hydrothermal method using emulsion systems consisting of aqueous phase, petroleum ether (PE) as the oil phase and biodegradable Tomadol 23–6.5 as the nonionic surfactant. (NH₄)₂HPO₄ and Ca(NO₃)₂ or Ca(OH)₂ were used as the phosphorus and calcium sources, respectively. The calcium source and emulsion composition had significant effects on the stoichiometry, crystallinity, thermal stability, particle size and morphology of final products. Disperse HA crystals with a 160 nm length and aspect ratio of ca. 6 were formed in an emulsion system containing 10 wt% PE, 60 wt% water and 30 wt% surfactant. The HA particles had needle morphology with a specific surface area of . With this technique, HA nanopowders with specific surface areas in the range of 72– were produced.