CdGeAs2多晶合成研究

以高纯(6N)Cd、Ge和As单质为原料,按CdGeAs_2的化学计量比配料,采用机械振荡和温度振荡相结合新方法合成出CdGeAs_2多晶锭,经X射线粉末衍射分析表明合成产物为高纯单相的CdGeAs_2多晶.用20℃/min的升温和降温速率对合成的CdGeAs_2多晶进行了DTA分析,结果显示CdGeAs_2多晶的熔化温度为669.24℃、结晶温度为615.55℃.根据DTA分析结果设计CdGeAs_2晶体生长温场,采用改进的Bridgman法生长出外观完整、尺寸为φ15 mm×45 mm的CdGeAs_2晶体,并对其进行解理实验,获得了完整、光滑的解理面,经XRD分析结果显示,连扫谱呈现(101)面的四级衍射峰,(101)面回摆谱峰尖锐、对称性好.     

Research on crystal growth and properties of a new nonlinear optical crystal: Bismuth borate BiB3O6

BiB₃O₆ (BIBO) single crystals with sizes of 44 mm × 24 mm × 10 mm and weight of 24.7 g have been successfully grown by the top-seeded method. In this note, the preparation of seed, the growth of crystal and some problems encountered are reported. The lattice parameters of BIBO area =7.1203(7)?,b = 4.9948(7)?,c = 6.5077(7)?,β= 105.586(8) ?,V=222.93(5)?³, which were determined by BRUKER-P4 four-circle diffractometer. BIBO is biaxial crystal and the relative orientation of (X, Y, Z) with regard to (a, b, c) is:X // b, (Y, c) =47.2°, (Z, a) = 31.6°, determined by the X-ray analysis combined with polarized microscopy. The second-harmonic-generation (SHG) conversion efficiency of the sample for 1.064 μm light is up to 67.7%. We have also obtained the third harmonic generation (THG) of 1.064 μm, namely, 1.064 μm + 0.532 μm →0.355 μm. BIBO crystal is free of moisture and hygroscopy.     

4,5-二氮芴-9-酮合钴配位超分子化合物的合成、晶体结构与热稳定性

通过溶剂热合成法,在甲醇/乙醇体系中由多吡啶配体4,5-二氮芴-9-酮(dafo)与钴(Ⅱ)自组装获得了配位超分子化合物(NO₃)₂。利用X-ray射线单晶衍射技术对其晶体结构进行了表征,并通过同步热分析仪进行了热稳定性分析。     

Preparation, characterization and photocatalytic activity of N-doped TiO2 nanocrystals

N-doped TiO₂ nanocrystals were prepared using titanium alkoxide as precipitant with different proportional materials. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and UV-vis diffuse reflectance spectra. It is confirmed experimentally that the photocatalytic activity of N-doped TiO₂ is much higher than that of Degussa P25, when used for the degradation of crystal violet. The degradation kinetics follows an apparent first-order reaction, which is consistent with a generally observed Langmuir-Hinshelwood mechanism. The doping of TiO₂ with nitrogen significantly increases the absorption in the region of visible light. The energy of the band gap of N-doped TiO₂ is 2.92 eV. The better performance of N-doped TiO₂ can be explained by the fact that it is also excited with longer-wavelength light.     

单温区管式炉气相输运生长NbSe_2超导单晶

化学气相输运(CVT)生长单晶通常采用双温区管式炉。利用普通单温区管式炉中的温度梯度实现了化学气相输运,并成功生长出了Nb Se2单晶。运用扫描电子显微镜,X射线衍射仪等方法对制备的Nb Se2单晶进行了形貌和结构的表征,并测量了低温下Nb Se2单晶的磁化率和电阻性质。结果表明,实验上生长出来的Nb Se2单晶具有金属光泽,晶体尺寸约为2 mm×2 mm,超导转变温度和转变宽度分别为7.1 K和0.3 K,超导体积分数约为79%。因此,单温区管式炉生长晶体的方法也可用于其他功能材料单晶的制备。     

毫米级单晶Mn12-Ac磁性分子团簇的制备及表征

文中详细介绍了毫米级Mn^₁₂-Ac单晶的制备方法。讨论了升温速率和恒温时间对晶体生长的影响,当以8min/℃的升温速率升温至55℃且保持30min时,获得了c轴方向长度为3mm左右的单晶。通过对晶体的X射线衍射（XRD）、等离子体发射光谱分析（ICP）以及磁滞回线测量,证实实验制备的晶体质量高,晶体缺陷少,可以更清晰地观察到宏观量子隧穿现象。     

Non-catalytic nucleation coating for undercooled Cu50Ni50 melt

A non-catalytic nucleation coating (B-F3) was prepared by the high temperature curing process of the sol-gel glass film based on the viscous flow mechanism of the coating. X-ray diffraction technology was adopted to study the crystallization behavior of the coating as a function of treating temperature. It was evident that no crystallization phenomenon happened on the coating which kept stable after the heat treatment of 60 min at 1773 K. The purified melt of Cu₅₀Ni₅₀ was selected to evaluate the effectiveness of undercooling heredity of the coating in the undercooling experiments. The maximum undercooling of the melt solidified in the coated mold could reach 236 K. Based on the solidified microstructural evolution at different undercoolings, a single crystal of the alloy Cu₅₀Ni₅₀ was achieved with no aid of the selection process of the crystal in the mold with the B-F3 coating by means of undercooling technology.     

新稀土金属间化合物晶体结构及高温晶格热膨胀性能研究

[目的]研究稀土-过渡族金属合金体系中的新稀土金属间化合物,挖掘稀土合金与化合物的新应用。[方法]利用扫描电子显微镜和能谱仪分析合金样品及其组成物相的成分,采用X射线粉末衍射技术研究和测定新金属间化合物的晶体结构及高温晶格热膨胀性能,并对所研究的新金属间化合物的高温热膨胀性能进行总结分析。[结果]不同的合金元素可以形成结构类型相同的晶体结构,得到了部分新金属间化合物的晶格热膨胀系数,这些新稀土金属间化合物的平均晶格热膨胀系数在10~(-6)到10~(-5)数量级之间,它们的平均单胞体积热膨胀系数也在同一数量级。[结论]化学性质相近的合金元素可以相互替代形成同构型金属间化合物。利用X射线粉末衍射同构法可测定新化合物的晶体结构,该法适用于解析二元、三元乃至多元新化合物的晶体结构。所研究的新稀土金属间化合物的热膨胀系数分别满足其各自所属晶系的热膨胀关系。     

基于POMs的化合物合成与电化学性质

多金属氧酸盐（POMs）作为一类新颖、独特的无机构筑单元,可以通过调节合成条件使端氧或桥氧活化,从而得到多种化合物。为了研究POMs的电化学性质,选择Keggin-型磷钼酸和1,4-双(咪唑基)丁烷（L）,通过水热法合成了一种新的基于多金属氧酸盐的无机-有机杂化化合物(H₂L)₃(PMo₁₂O₄₀)₂,研究了该化合物对于亚硝酸盐的电催化活性。通过元素分析,红外、热重、X射线单晶衍射和X射线粉末衍射对化合物进行表征,探讨了合成过程中反应条件(例如pH值)与目标化合物结构之间的关系,测试了目标化合物的电化学性能和电催化性质。X射线单晶衍射分析表明,多酸是通过氢键与配体连接的三维结构,属于Triclinic晶系,空间群为P-1;荧光分析表明,化合物的荧光主要来自配体贡献。该化合物对亚硝酸盐有较好的电催化活性,有望用于实际样品中亚硝酸盐的检测。     

［Ni(phen) 3］2［Ni(PO4)2(H2PO4)6(OH)6(MoO2)12］的合成和晶体结构

利用中温水热技术合成一种新型还原型钼磷酸盐： ［Ni(phen) ₃］₂［Ni(PO₄)₂(H₂PO₄)6(OH)₆(MoO₂)₁₂］(phen: 邻菲啰啉), 并通过单晶X射线衍射技术测定了该化合物的晶体结构.该化合物属于三斜晶系, P1空间群, 晶胞参数: a=1.404 2(3) nm, b=1.405 0(3) nm, c=1.408 2(3) nm, α=74.53(3)°, β=74.72(3)°,γ=74.81(3)°, V=2.527 6(9) nm3, Z=1, R1=0.076 2, wR2=0.168 6.     

Flux-Bridgman growth and characterization of Mn-doped ZnO single crystals

Mn-doped ZnO single crystals have been grown by the flux-Bridgman method from a high temperature solution of 24% ZnO-76%PbF_2(molar fraction).A fast nucleation was induced by the gas-cooling system at the bottom of the Pt crucible.A red Mn.ZnO crystal up to 13 mm×15 mm×(3-4) mm was obtained.Powder XRD patterns showed that the as-grown crystals were in wurtzite structure.Electron Probe Microanalyser(EPMA) revealed that some PbF_2 inclusions formed due to fast nucleation.The additional Raman mode at 524 cm ' ...     

β-Ｄ-吡喃葡萄糖叠氮化物的合成及晶体结构

合成了β-Ｄ-O四乙酰基糖基叠氮化合物， 并得到单晶， 经X射线衍射方法解析， 其晶系属于单斜晶系，P2₁空间群， 其中a=0.759　6(6) nm,b=1.518　4(13) nm，c=1.641　2(14) nm，V=1.893　0(3) nm³，α=90.00°，β=90.045(1)°，γ=90.00° ，Z=2. 在晶体结构中， 六元糖环采取经典⁴C₁椅式构象， 糖环上所有 的取代基均以平伏键存在， 其中叠氮基不是以直线型结构存在， 呈现一定的弯曲现象.     

水热组合方法在合成亚磷酸镓中的应用

应用水热溶剂热组合合成方法, 在Ga-H₃PO₃-1,2-dap(1,2-丙二胺)-EG（乙二醇）/H₂O体系中合成了3种三维空旷骨架亚磷酸镓化合物以及1种磷酸镓化合物, 对其进行了红外光谱、 元素分析及X射线单晶衍射结构分析, 并讨论了合成因素对晶化的影响.     

Synthesis and X-ray crystal structure of a new manganese 18-metallacrown-6

0　IntroductionThemetalionsinmetallamacrocylesformedbysupramolecularself assemblycantaketrigonal,square planar,andtetrahe dralconfiguration[1 ,2 ] .Metallacrownisaspecialclassofmetalla macrocyle,theyareanalogoustocrownethersinbothstructureandfunctionexceptthatthemetalionsarenowtakingthepositionsofcoordinationatomsincrownether[3,4] .Themetallacrownswithdifferentnumberof [M—N—O]repeatunithavedifferentcavitysizes,suchas 9 MC 3[5 7] ,12 MC 4 [4,8 1 4 ] and 15 MC 5 [1 5] .Thereportedazameta…     

Thermoelectric properties of polycrystalline (SnSe)1-x(AgSnSe2)x/2 alloys

SnSe is considered as a thermoelectric material with great potential and advantages due to the record of high thermoelectric figure of merit (ZT) of 2.6 ?at 923 ?K in single crystals. However, it is difficult to use single crystal SnSe in practice due to its poor mechanical properties and high manufacturing costs. Meanwhile, the polycrystalline SnSe also is also not suitable for applications due to its much lower thermoelectric performance compared with single crystal SnSe. Therefore, improving the thermoelectric properties of polycrystalline SnSe has become a hot research topic. In this paper, AgSnSe₂ doped into SnSe to increase the carrier density of the system and thus improve its thermoelectric properties. It is found that the addition of AgSnSe₂ can effectively improve the thermoelectric performance of polycrystalline SnSe. A peak ZT of 0.81 was obtained at 713 ?K for (SnSe)_0.95(AgSnSe₂)_0.025, which is 305% higher than that of the undoped one. This reveals that AgSnSe₂-doped SnSe alloy may become a thermoelectric material system with great application potential and significance.     

The relationship between nacreous layer color and CaCO3 crystal orientation

The pearl or nacreous layer of mollusk shell is composed of CaCO₃ aragonite crystals. The factors affecting their color are very complex, such as metal elements, chromoprotein, and nucleation materials, we analyzed the crystal orientation of nacreous layers with different color prepared from fresh water clamsHyriopsis cumingii Lea by X-ray diffraction. The results show that the crystal CaCO₃ orientation on specific plane is responsible for the color of pearl and nacreous pearl color. Supported by National Natural Science Foundation of China and Morning Sunlight Program of Wuhan City Government. Jiang Xinnong: born in 1970, Lecturer     

Harmonic mixing of Bi2Sr2CaCu2O8+x intrinsic junction at millimeter waveband

Using intrinsic Josephson junctions in Ba₂Sr₂CaCu₂O_8+x single crystal, harmonic frequency mixing at 8 and 3 mm wavebands was successfully demonstrated at liquid nitrogen temperatures with harmonic numbers up to 68 and 50 respectively. The dependences of intermediate frequency output on the local oscillator power and dc bias were carefully studied.     

Growth habit of polar crystals

Using coordination polyhedron rule, growth habit of polar crystals such as ZnO, ZnS and SiO₂ is investigated. It shows that the growth rates in the positive and negative polar axis directions are different. The theoretical growth habit of ZnO crystal is hexagonal prism and the growth rates of its various faces are: V_{0001} > V_{0111} >V_{0110} > V_{0111} > V_{0001}. The growth habit of ZnS crystal is tetrahedron and its growth rates of different crystal faces are: V_{111}>V_{001}>V_{001}=V_{100} = V_{010}>V_{111}. The growth rate relationship between positive and negative polar axis directions of SiO₂ crystal is V_[1120] > V_[1120]. These results are in agreement with the growth habits observed under hydrothermal conditions. The different growth rates between positive and negative polar axis directions cannot be explained by PBC theory.     

二维层状结构磷酸锌化合物的水热合成与结构表征

在水热条件下, 制得了ZnHPO₄单晶. 对其进行了粉末X射线衍射分析、 红外光谱、 元素分析和单晶X射线衍射分析. 单晶结构分析结果表明, 该晶体属于单斜晶系, P2(1)/c空间群, a=0.462　51(14) nm,b=1.360　8(4) nm, c=0.582　84(18) nm, β=98.752(5)°, V=0.362　56(19) nm³, Z=2, M＝161.35, R₁＝0.074 2, wR₂＝0.229　6.     

γ′-Fe4N纳米晶薄膜的结构及低温磁性

采用直流磁控溅射方法, 在Si(100)单晶衬底上制备γ′-Fe₄N纳米晶薄膜样品, 并利用X射线衍射(XRD)和振动样品磁强计(VSM)对样品的结构和磁性进行测试分析, 给出了比饱和磁化强度及矫顽力与温度的关系. 结果表明, 样品沿(111)晶面择优生长, 具有单一的易磁化方向, 且易磁化方向平行于（111）晶面. 随着测量温度的降低, γ′-Fe₄N纳米晶薄膜样品的比饱和磁化强度σ_s增加, 矫顽力H_c增大, 剩磁比σ_r/σ_s减小. 通过理论拟合确定了比饱和磁化强度与矫顽力随温度的变化关系, 矫顽力随温度的变化满足T^1/2规律, 比饱和磁化强度σ_s与温度不满足Bloch的T^3/2规律, 表明在80~350 K温度范围内自旋波之间存在较强的相互作用. 