ZnFe2O4纳米棒的制备和性能研究

以硫酸锌、氯化亚铁和草酸铵为原料,采用水热法和热分解法成功制备了ZnFe2O4纳米棒,并利用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、X射线能量色散分析谱仪(XEDS)、高分辨透射电子显微镜(HRTEM)、选区电子衍射(SAED)和振动样品磁强计(VSM)等测试手段对样品的化学成分、形貌、晶体结构和磁性能进行了表征.结果表明,制备的ZnFe2O4为结晶良好的单相尖晶石型结构,没有杂峰出现.样品形貌为一维纳米棒状结构,分散性良好.ZnFe2O4纳米棒直径约为200nm,长度约为1～2 μm,纳米棒由晶粒尺寸在15 ～ 20 nm范围内的ZnFe2O4单晶颗粒构成.ZnFe2O4纳米棒在室温下具有超顺磁特性.     

Fe_3O_4单晶纳米棒和量子点的水热合成与表征

本文以FeSO_4·7H_2O为铁源,采用LSS反应机制控制合成了Fe_3O_4单晶纳米棒和量子点,并根据不同反应条件下反应生成的产物形貌推断了反应机理.采用X-射线衍射仪(XRD)、透射电子显微镜(TEM)对产物进行表征.室温下分别测试了Fe_3O_4单晶纳米棒和量子点的磁滞回线,检测得到纳米棒和量子点饱和磁化强度磁化率(Ms)分别为44.26 emu/g和60.09 emu/g,矫顽力(H_c)分别为132.3 Oe和143.2 Oe.     

羟基硅酸镁纳米棒的制备及光吸收性能研究

以Mg(NO3)2·6H2O和纳米SiO2为原料,采用水热法,合成了Mg3Si2O5(OH)4纳米棒.采用X射线衍射(XRD)及场发射扫描电子显微镜(FE-SEM)对样品的物相组成和微观形貌进行了表征.并采用紫外-可见漫反射测试(UV-vis DRS)测定了样品的光吸收性能,DRS结果显示Mg3Si2O5(OH)4纳米棒的光吸收主要集中在紫外光区,结合Kubelka-Munk方程计算得出Mg3Si2O5(OH)4纳米棒的光学带隙为4.98 eV.     

纳米结构氧化铁棒束的制备、表征及光学性质

以三氯化铁(FeCl3·6H2O)和氨三乙酸(N(CH2COOH)3)为主要原料,在160℃反应12h得到了空心管状的白色前驱体,再经500℃煅烧2h得到了纳米结构氧化铁棒束.通过热重分析(TG)、光学显微镜、X射线衍射(XRD)、扫描电子显微镜(SEM)、红外光谱(FT-IR)、紫外-可见光谱(UV-Vis)对所得产物进行了表征.结果表明:所得白色前驱体经500℃煅烧后全部转化为六方相的氧化铁(α-Fe2O3),形貌为含微孔结构的棒束,直径约为2μm,其结构单元为含微孔结构的纳米棒,这些棒的直径为30～50 nm,长度约16μm;紫外数据表明所得氧化铁棒束的最大吸收波长为546nm,带宽吸收约在685 nm处,发生红移.     

溶剂热法制备不同形貌纳米Lu2O3粉体

本文以水、丙酮、乙醇、乙二醇为溶剂,采用溶剂热法制备了不同形貌的纳米氧化镥(Lu2O3粉)粉体前驱体,将前驱体在400～800 ℃条件下煅烧2 h制得了不同形貌的Eu3+:Lu2O3粉体.研究发现,所用溶剂的物理性质对产生特定形貌的样品具有重要的影响,以水和丙酮为溶剂,可制得具有较高长径比的Lu2O3纳米棒,而当溶剂为乙醇和乙二醇时,所得Lu2O3粉体为等轴状的纳米颗粒.     

HPO42-与H2PO4-在水热法制备CeO2纳米颗粒过程中的影响

以Ce(NO3)3·6H2O、Na5P3O10和Na3PO4·12H2O为原料,用水热法在180℃反应60h分别制备了CeO2纳米八面体和纳米棒,且对Na5P3O10与Na3PO4 · 12H2O系统同时调节pH =2时180℃反应12 h制备了纳米棒.通过XRD、FE-SEM、TEM等方法对CeO2纳米棒和纳米八面体进行了测试和分析.结果表明,对于Na5P3O10与Na3PO4·12H2O系统,初始时CeO2八面体与纳米棒共存,但随着水热时间的延长,Na5 P3O10系统中CeO2八面体成为主要产物,而在Na3PO4·12H2O系统中CeO2纳米棒成为主要产物.Na5P3O10水解产生的HPO42-是CeO2纳米八面体形成的主要原因,而Na3PO4·12H2O水解产生的H2PO4-是纳米棒形成的主要原因.     

CoC2O4·2H2O纳米晶形貌可控合成

通过简单调节反应介质热塑性酚醛树脂与乙二醇配比,选择性地制备了CoC2O4·2H2O纳米棒和纳米片晶体或其两种形貌晶体混合物.样品热重和差示扫描量热(TG-DSC)、X射线粉体衍射(XRD)、场发射扫描电镜( FESEM)实验表明:以热塑性酚醛树脂为反应介质得到了COC2O4·2H2O纳米棒;以乙二醇为反应介质得到了CoC2O4·2H2O纳米片;逐渐增大乙二醇和酚醛树脂质量比,实现了CoC2O4·2H2O形貌由纳米棒形貌转变为纳米片形貌.基于不同晶体形貌和实验结果,提出了棒状和片状COC2O4·2H2O可能的形成机理模型以解释两种形貌COC2O4·2H2O纳米晶的生长行为.     

不同形貌纳米α-Fe2O3粉体水热合成及其催化高氯酸铵热分解研究

以Fe2(SO4)3为原料,在不同温度和时间进行水热反应,产物经过600℃下热处理6h,得到了不同形貌的纳米α-氧化铁.通过XRD、SEM、TEM对α-Fe2O3的物相组成、形貌和微观结构进行表征.结果表明,花片状、海胆状、草莓状和哑铃状等多种形貌的产物均由纳米α-Fe2O3颗粒组装而成,纳米颗粒大小为10～50 nm.采用DTA分析了赤铁矿α-Fe2O3对高氯酸铵(AP)的催化性能.结果表明水热反应条件140℃保温4h获得的花片状α-Fe2O3,使得高氯酸铵(AP)热分解温度提前了67.2℃,较其它形貌,催化效果明显.     

水热法合成Gd2O3∶Dy3+纳米棒及发光性能

以氢氧化钠为沉淀剂,采用水热方法制备了Gd2O3∶Dy3+纳米棒.通过红外光谱、扫描电镜及X射线衍射对前驱体及目标产物的物相结构、微观形貌进行了分析表征,通过荧光分光光度计测试了所得Gd2O3∶Dy3+的发光性能.结果表明:水热前驱体为六方相氢氧化钆(镝),经900℃焙烧得立方相的Gd2O3∶Dy3+.所得G d2O3∶Dy3为直径约100 nm,长度约500 nm～1μm的纳米棒.其激发光谱由一系列激发峰组成,峰值分别位于239 nm、279 nm、314 nm、353 nm,最强峰位于279 nm处;发射光谱主要由两部分组成,分别为460 ～500 nm的蓝光和560～590nm的黄绿光发射峰(带),均属于Dy3+的特征发射,且后者的强度远高于前者,因此,在紫外光激发下呈黄光发射.     

静电纺In2O3纳米纤维的光致发光性能研究

利用静电纺丝技术结合高温煅烧方法制备了一系列多孔结构的一维In2O3无机纳米纤维,并探讨了煅烧温度对产物发光性能的影响及其发光机理.利用热重仪(TGA)、X射线衍射仪(XRD)、傅里叶红外光谱仪(FT-IR)、扫描电子显微镜(SEM)分析了产物的热分解情况、晶型、组分和形貌;通过紫外-可见光谱仪和荧光分光光度计分析研究了一维In2O3纳米纤维的光吸收性能和光致发光性能.结果表明:静电纺前驱体复合纳米纤维成型良好,经500℃、600℃、700℃、800℃高温煅烧后仍保持纤维结构,但纤维直径明显减小,当煅烧温度达到800℃时,纤维出现中空结构;不同温度下煅烧所得In2O3均为立方铁锰矿型;随着煅烧温度的升高,In2O3纳米颗粒粒径逐渐增大;In2O3纳米纤维的的最大紫外吸收峰位于300nm左右;在室温下,In2O3纳米纤维经274nm光激发后在553 nm处出现较强的绿光发射峰.     

CsI-LiCl共晶材料的坩埚下降法生长与闪烁性能研究

本文采用坩埚下降法,在真空密封的石英坩埚中成功生长出CsI-LiCl与CsI-LiCl:Na共晶闪烁体。通过扫描电子显微镜(SEM)观察晶体微结构表明该共晶中LiCl相与CsI相存在周期性的层状排列,CsI相的厚度在5 μm左右。共晶样品的X射线激发发射谱显示在CsI-LiCl和CsI-LiCl:Na共晶样品存在缺陷发光,在CsI-LiCl样品中还观察到了纯CsI的自陷激子(STE)发光。CsI-LiCl样品在α粒子激发下的多道能谱中观察到明显的全能峰,这一结果证明CsI-LiCl共晶可用于热中子探测的潜力。     

静电纺丝法制备CeO2微纳米纤维及其除氟性能

以聚丙烯腈(PAN)为载体,六水合硝酸铈[Ce(NO₃)₃·6H₂O]为原料,采用静电纺丝法制备了Ce(NO₃)₃/PAN纤维,在空气中热处理得到CeO₂微纳米纤维,通过XRD、BET和SEM对CeO₂微纳米纤维进行表征。采用静态吸附实验探讨了CeO₂微纳米纤维去除水溶液中氟离子的性能,考察了溶液pH值、初始氟离子浓度及共存阴离子等对吸附性能的影响。结果表明,pH=3时,CeO₂微纳米纤维对F^-的吸附性能最佳,CeO₂吸附量随着F^-浓度的增大呈上升趋势。CeO₂微纳米纤维对F^-的吸附等温线遵循Langmuir模型,二级动力学模型能很好地描述CeO₂微纳米纤维对F^-的吸附过程。CeO₂微纳米纤维的除氟性能优良,可为其实际应用提供理论参考。     

Triethyl ammonium salt of O,O′-bis(p-tolyl)dithiophosphate, [Et3NH]+[(4-MeC6H4O)2PS2]−

Triethyl ammonium Salt of O,O′-bis(p-tolyl)dithiophosphate and O,O′-bis(m-tolyl)dithiophosphate have been obtained by reaction of p- and m-cresol, respectively with P₂S₅ in toluene and have been characterized by elemental analysis, IR, ¹H and ³¹P NMR spectroscopy. The molecular structure of O,O′-bis(p-tolyl)dithiophosphate has been determined. Crystal data: [Et₃NH]⁺[(4-MeC₆H₄O)₂PS₂]⁻: Monoclinic, P2₁/c, a=15.2441(9) ?, b=10.415(2) ?, c=3.9726(9) ?, β=91.709(7)°, V=2217.5(1) ?⁻³, Z=4.Supplementary materials Additional material available from the Cambridge Crystallographic Data Centre (CCDC no. 600927 for [Et₃NH]⁺[(4-MeC₆H₄O)₂PS₂]⁻ comprises the final atomic coordinates for all atoms, thermal parameters, and a complete listing of bond distances and angles. Copies of this information may be obtained free of charge on application to The Director, 12 Union Road, Cambridge CB2 2EZ, UK (fax: +44-1223-336033; email: deposit@ccdc.cam.ac.uk or www:http://www.ccdc.cam.ac.uk).     

Crystal structure of Zn4Na(OH)6SO4Cl·6H2O

The structure of Zn₄Na(OH)₆SO₄Cl·6H₂O, a secondary mineral from Hettstedt, Germany, was determined by single-crystal X-ray diffraction. The crystals are hexagonal,a=8.413(8),c=13.095(24) Å, space group $P\bar 3$ , Z=2. The structure was refined to R=0.0554 and R_w=0.0903 for 970 reflections with I≥3σ(I). The structure can be described as zinc hydroxide layers perpendicular toc, from which sulfates and chlorides extend. The layers are held together by a system of hydrogen bonds involving hexaaquo Na⁺ ions which occupy the interlayer space.     

Synthesis and Crystal Structure of 5-[2-(6-bromonaphthalenyloxymethyl)]-3-(4-morpholinomethyl)-1,3,4-oxadiazole-2(3<Emphasis Type="Italic">H</Emphasis>)-thione

Abstract  The title compound, C₁₈H₁₈BrN₃O₃S, a derivative of 1,3,4-oxadiazole, crystallizes in the triclinic space group P-1 with unit cell parameters a = 6.8731(3), b = 8.9994(4), c = 15.7099(6) ?, α = 92.779(3)°, β = 130.575(3)°, γ = 107.868(4)°, Z = 2. The dihedral angle between the mean planes of the planar naphthyl and morpholine (chair) rings with the planar oxadiazol ring is 50.1(8) and 76.8(6)°, respectively. The planar naphthyl ring is twisted 52.2(5)° with the mean plane of the morpholine ring. A group of four intermolecular close contacts are observed between a bromine atom and hydrogen atoms from the closely packed naphthyl, morpholine and oxy–methyl groups in the unit cell. These molecular interactions in concert with an additional series of π–π stacking interactions that occur between the center of gravity of the two 6-membered rings of the naphthalene group influence the twist angles of each of these three groups. A MOPAC AM1 calculation of the conformation energy of the crystal structure [226.0128(9) kcal] compared to that of the minimum energy structure after geometry optimization [29.9744(1) kcal] reveals a significantly reduced value. The twist angles of the three groups above also change after the AM1 calculation giving support to the influence of both intermolecular C–H···Br short-range interactions and Cg π–π stacking interactions on these angles which therefore play a role in stabilizing crystal packing. Graphical Abstract  Crystal structure of 5-{[(6-bromonaphthalen-2-yl)oxy]methyl}-3-(morpholin-4-ylmethyl)-1,3,4-oxadiazole-2(3H)-thione, C₁₈H₁₈BrN₃O₃S, is reported and its geometric and packing parameters described and compared to a MOPAC computational calculation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Crystal structure of irisolidone from the flowers of Pueraia lobata

Irisolidone (5,7-dihydroxy-6,4′-dimethoxyisoflavone) was isolated from the flowers of Pueraia lobata and its crystal structure was examined by X-ray single crystal diffraction. The crystal structure of irisolidone is monoclinic, space group P2₁/c with a = 15.491(9) ?, b = 7.895(4) ?, c = 13.321(7) ?, β = 110.546(9)° and Z = 4. Hydrogen bonding and aromatic π–π stacking assemble the title compound into a three-dimensional networking structure.     

X-ray analysis of sideroxol from <Emphasis Type="Italic">Sideritis leptoclada</Emphasis>

Sideroxol (1), a kaurane diterpene which has the ent-7α,18-dihydroxy-15β,16β-epoxykaurane structure (MW = 320.47, C₂₀H₃₂O₃) was obtained from the acetone extract of Sideritis leptoclada plant as well as from some other Sideritis species. It crystallizes in the orthorhombic space group P2₁, 2₁, 2₁ with a = 10.967(3), b = 24.555(5), c = 6.372(4) Å, Dc = 1.240 g cm⁻³, Z = 4, and refines to R = 0.065 for 721 independent reflections. The skeleton consists of three fused six-membered rings and a five-membered ring with fused epoxide. The six membered rings exhibited slightly distorted chair conformation. In addition to sideroxol, two kaurane and five kaurene diterpenes were isolated from the hexane and acetone extracts of the studied plant.     

New zeotype borophosphates with chiral tetrahedral topology: (H)0.5M1.25(H2O)1.5[BP2O8]·H2O (M = Co(II) and Mn(II))

Two new isostructural open‐framework zeotype transition metal borophosphate compounds, (H)_0.5M_1.25(H₂O)_1.5[BP₂O₈]·H₂O (M = Co(II) and Mn(II)) were synthesized by mild hydrothermal method. The structure of compounds were characterized by single‐crystal X‐ray diffraction which have ordered, alternating, vertex‐sharing BO₄, PO₄, and (MO₄)OM(H₂O)₂ groups with hexagonal, P 6₁ 2 2 (No 178) space group and unit cell parameters for Co a = 9.4960(6) Å, c = 15.6230(13) Å, for Mn a = 9.6547(12) Å, c = 15.791(3) Å, Z = 1 for both of them. TGA/DTA analysis, IR spectroscopy were used for characterization. Magnetic susceptibility measurements for both of the compound indicate strong antiferromagnetic interaction between metal centers. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Photoluminescence characteristics of Mg- and Si-doped GaN thin films grown by MOCVD technique

We have studied the optical, structural and surface morphology of doped and undoped GaN thin films. The p- and n-type thin films have been successfully prepared by low-pressure MOCVD technique by doping with Mg and Si, respectively. The different carrier concentrations were obtained in the GaN thin films by varying dopant concentrations. Photoluminescence (PL) studies were carried to find the defect levels in the doped and undoped GaN thin films at low temperature. In the undoped GaN thin films, a low intensity and broad yellow band peak was observed. The donor–acceptor pair (DAP) emission and its phonon replicas were observed in both the Si or Mg lightly doped GaN thin films. The dominance of the blue and the yellow emissions increased in the PL spectra, as the carrier concentration was increased. The XRD and SEM analyses were employed to study the structural and surface morphology of the films, respectively. Both the doped and the undoped films exhibited hexagonal structure and polycrystalline nature. Mg-doped GaN thin films showed columnar structure whereas Si-doped films exhibited spherical shape grains.     

Solubility of Ag2O into the Na2O–B2O3–Al2O3 system

The solubility of Ag₂O was measured for the Na₂O–B₂O₃ and Na₂O–B₂O₃–Al₂O₃ system with the rotating crucible method and static method, respectively, under air atmosphere at temperatures ranging from 1273 to 1423 K. The contamination of melts from crucibles could be avoided by the rotating crucible method, with which it became possible to measure the solubility of Ag₂O for the Na₂O–B₂O₃ system above the melting point of Ag for the first time. It was found that the addition of Na₂O decreases the solubility of Ag₂O while the addition of Al₂O₃ had little effect on the solubility. The effect of Na₂O and Al₂O₃ on the solubility of Ag₂O is expressed by interaction coefficients and is analyzed in terms of the basicity of melts. The solubility of Ag₂O in Na₂O–B₂O₃–Al₂O₃ melts increased with increased temperature. This phenomena was explained by a small enthalpy change in oxidation of silver.