Absorption and ionic conductivity of oxygen-containing SrF2 crystals

An absorption band at 3644 cm⁻¹ is caused by isolated OH⁻ ions. O⁻ ions cause an absorption band at 213 nm the oscillator strength of which is 0.020. Charge-compensation of O⁻ ions is effected by F⁻ ion vacancies (F). As for CaF₂ crystals there occur monomers and dimers of [O⁻ – F] complexes. The mass action constants of association of F with oxygen centres are K_AD = ⅓ exp (4.28 – 0.82 eV/kT) for [O⁻ – F], K_AT = 4 exp (17.4 – 1.25 eV/kT) for [2 O⁻ – F] and K_AQ = exp (4.2 – 0.89 eV/kT) for [2 O⁻ – 2 F].     

EXAFS study of 20GaF3–15InF3–20CdF2–15ZnF2–20PbF2–10SnF2 glass

The structure of 20GaF₃–15InF₃ –20CdF₂–15ZnF₂–20PbF₂–10SnF₂ glass (GICZPS) was studied by EXAFS and XRD. The results indicate that Ga³⁺ is more stable than In³⁺ in the GICZPS glass network, and Zn²⁺ is the glass modifier, the coordination number of which is 6.     

Hydrothermal synthesis and electrochemical properties of MnO2 nanostructures

Manganese oxide (MnO₂) nanowires with diameters of 40–50 nm and lengths up to several micrometers have been successfully synthesized through a simply hydrothermal route. The influences of synthetic parameters, such as reaction time, and reaction temperature, on the growth and morphologies of MnO₂ nanowires have been investigated. It is found that MnO₂ nanowires can be evolved into MnO₂ microrods with the reaction time/temperature increased. The electrochemical characterization of MnO₂ nanostructures was carried out in 1 M Na₂SO₄ aqueous electrolyte at the scan rate of 10 mV s^‐1. The results indicate that the MnO₂ microrods obtained when the reaction performed at 200 °C for 24 h showed the best performance for supercapacitor. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Hydrothermal synthesis of MoS2 nanowires

The MoS₂ nanowires with diameters of 4 nm and lengths of 50 nm were synthesized by a hydrothermal method using 0.36 g MoO₃ and 1.8 g Na₂S as precursors in 0.4 mol/l HCl solution at 260°C. The products are characterized by XRD, XPS, TEM, HTEM and BET. Results show that the as-prepared MoS₂ nanowires consist of 1–10 sulfide layers with BET surface areas of 107 m²/g. The possible reaction route and the formation mechanism of the MoS₂ nanowires are discussed. The effects of exterior conditions such as pH value, temperature, concentration of precursors and additives on the particle size and morphology of MoS₂ crystallites were investigated.     

Hydrothermal synthesis and characterization of (N(C2H5)4)4[VMo12V2O44]

The hydrothermal reaction of a mixture of Na₂MoO₄·2H₂O, V₂O₅, pyromellitic acid (1,2,4,5‐C₆H₂(COOH)₄), (C₂H₅)₄NCl and 0,1 M H₂SO₄ for 88 h at 180°C gives blue needle‐like crystals of [V^IV₂O₂(H₂O)₂ (C₆H₂(COO)₄)] in 20% yield (based on V) and dark blue prismatic crystals of the title compound, mixed‐valance (N(C₂H₅)₄)₄[VMo₁₂V₂O₄₄], 1, in 12% yield (based on Mo). 1 was investigated by means of elemental analysis, thermogravimetry, Fourier Transform Infrared Spectroscopy and Single Crystal X‐ray Diffraction Methods. Crystal data for the compound: monoclinic space group P2₁/c (No:14), a=13.7815(12) b=13.0271(9) c= 21.189(2) Å, β= 113.909(7)°, Z=2. Although [XM₁₄O₄₂]^‐n (X=P, Si, Ge, V and M=Mo and/or V) cores have been previously determined, this is the first time that [VMo₁₂V₂O₄₄]^‐4 core is synthesized and characterized. The structural difference between 1 and these HPOMs is the coordinational geometry of the central metal atoms. The central vanadium in 1 has an octahedral coordination geometry, whereas in literature, the central V, P, Si and Ge atoms in [V₁₅O₄₂]^‐9 / [SiM₈V₆O₄₂]^‐4 / [PM₈V₆O₄₂]^‐5 / [GeM₈V₆O₄₂]^‐4 have tetrahedral coordinational geometry. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Anisotropy of the ionic conductivity of CsCu2Cl3 single crystals

The conductivity of CsCu₂Cl₃ single crystals (orthorhombic system, sp. gr. Cmcm) has been investigated for different electric-field directions, perpendicular to the crystallographic c axis and along it, in the temperature range 390–530 K. The increase in conductivity with temperature is due to the ion-carrier transport with activation energies E _a = 0.65 and 0.80 eV for the directions perpendicular to and along the crystallographic axis, respectively. The anisotropy of the crystal ionic conductivity is found to be σ_⊥c /σ_∥c ≈ 40 at 435 K. The thermally activated contribution to the conductivity in the CsCu₂Cl₃ structure is determined by the transport of Cu⁺ ions.     

氟化铅晶体中包裹体的显微观察与分析

本文根据偏光显微镜观察,把存在于立方氟化铅晶体中的包裹体分为三种类型:针状包裹体、板状包裹体和无规则形包裹体.根据EDS成分分析和XRD结构测定,认为针状包裹体的组成为铅的氧化物和氟氧化物,板状包裹体和无规则形包裹体为氟化铅的斜方相.针状包裹体是由于原料中的PbO杂质引起组分过冷而造成氧化铅和氟氧化铅小颗粒的定向排列.如果氧化物杂质含量不是很高,则通过掺入过量脱氧剂、提高固液界面处的温度梯度和降低下降速度,可以比较有效地减少甚至消除晶体中的针状包裹体.     

Hydrothermal synthesis and characterization of VO2 (B) nanorods array

Highly ordered nanorods array of B phase vanadium dioxide was firstly synthesized with n-butanol as the reducing agent via a simple hydrothermal method without using template. The samples have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FE-SEM). The size of VO₂ (B) nanorods has the dimension of 50–100 nm in diameter and about 1–5 μm in length. The samples were measured as electrode materials by charge–discharge technique and the VO₂ (B) nanorods array demonstrated a high specific capacity of 520 mAh/g at 0.2 C. The influence of reaction temperature on fabricating nanorods array has been studied. The possible growth mechanisms of formation of nanorods and assembly of array were discussed.     

Hydrothermal synthesis of new compounds

The recent results on hydrothermal synthesis and growth of crystals are described. The phase diagrams of crystallisation for polycomponent systems are given. Crystallisation of flourides, borates, phosphates, silicates and germanates of 1-2-3-4 valent elements are discussed as well as the role of mineralizer and temperature in hydrothermal processes. The crystallographic characteristics of new compounds are given. Some data on single crystal growth are represented for such compounds as zincite, sphalerite, nepheline, aluminum phosphate and potassium titanyl phosphates.     

Electrical conductivity of low-temperature carbons as a function of frequency

The electrical conductivity of anthracene carbon samples, heat treated to temperatures of 600, 650, 730 and 800°C is measured at variable frequency up to 100 MHz. The carbons heat-treated to 600 and 650°C have a specific behaviour of amorphous solids, whereas the carbons HTT 730° and 800°C have an electrical conductivity independent of the frequency. The experimental results are correctly explained by means of the equations developed by Pollak and Geballe. Analysis of the results points to the conclusion that a hopping conduction between localized states could be a possible process of conduction in such solids.     

Cu2ZnSnS4纳米粒子的水热合成及其光催化性能研究

以易获取的氯化铜、氯化锌、氯化亚锡等无毒材料为原料,采用水热合成法制备得到Cu2ZnSnS4纳米粒子.并采用XRD、SEM分析了不同反应温度和硫源对Cu2ZnSnS4纳米粒子的晶相结构、显微形貌的影响,并以降解罗丹明B为模型,研究了Cu2ZnSnS4纳米粒子的光催化性能.研究表明:在180 ℃下使用Na2S为硫源反应12 h所得的产物为形貌均一的多晶Cu2ZnSnS4纳米粒子;在该条件下制得的产物降解20 mg/L罗丹明B时,在LED灯光照150 min后其光催化效率达到98;以上且降解过程中逐步脱乙基生成4种中间产物.     

Hydrothermal synthesis of CdSe hierarchical microspheres

CdSe hierarchical microspheres have been successfully synthesized by a hydrothermal route at 120 °C for 16 h via a reaction between CdCl₂ and Na₂SeSO₃ in ionic liquid (1‐butyl‐3‐methylimidazolium bromide)‐water mixed medium. The structure and morphology of the as‐prepared products have been investigated by XRD and SEM, and the results indicate that the CdSe hierarchical microspheres have wurtzite structures and are self‐assembled by nanorods. It has been found that ionic liquid, reaction temperature, and reaction time have influence on the morphology of the products. The possible growth mechanism of CdSe with special morphology has been discussed. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Hydrothermal synthesis of ZnSe hollow micropheres

ZnSe hollow spheres aggregated from nanoparticles with size of 60∼100 nm have been successfully synthesized via simple hydrothermal routes. NaOH and cetyltrimethyl ammonium bromide (CTAB) were used to control the shape and size, respectively. The as‐prepared microspheres were characterized with powder X‐ray diffraction (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV‐vis spectroscopy. The results indicate that the products are well dispersed and uniform. The effect of two additives was discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Hydrothermal synthesis and formation of 4ZnO·B2O3·H2O whiskers via a new route

4ZnO·B₂O₃·H₂O whiskers were prepared from 2ZnO·3B₂O₃·3.5H₂O under hydrothermal process at 160 °C for 10 h. The synthesized product was characterized by XRD, SEM, TG‐DSC and FT‐IR. SEM results showed that the synthesized 4ZnO·B₂O₃·H₂O whiskers' length was about 3–10 μm and the diameter was 0.2–0.3 μm. Further study on the whiskers' growth process and mechanism showed that the formation of the whiskers went through three stages and the morphology of 4ZnO·B₂O₃·H₂O changed from irregular particles to rod‐like structures and finally to whiskers. The variation of the morphology of the 4ZnO·B₂O₃·H₂O whisker with the concentration of the starting material was investigated. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

On the change of low-temperature thermal conductivity of gap after bending

The thermal conduction of a sulphur-doped single crystal plastically deformed by bending at 963 K was measured between 2 and 50 K. The thermal resistivity W at temperatures > 14 K is practically independent on deformation. At lower temperatures W is found to be proportional to AT⁻³ before and to AT⁻³ + BT⁻² after deformation. A is due to boundary scattering, B due to dislocations.