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1.
Disilver Oxotellurate(VI), Ag2TeO4 Ag2TeO4 was synthesised by reaction of Ag2O and TeO2 applying an elevated oxygen pressure. According to a single crystal structure determination (C2/c, a = 9.0588(9), b = 9.2456(8), c = 13.623(1) Å, β = 91.758(8)°, Z = 12, 1289 independent reflections, R1 = 2.32 %, wR2 = 5.51 %), Ag2TeO4 contains a novel chain‐like polyanion with tellurium in an octahedral coordination. The TeO6 octahedra are connected via common edges and vertices in a way that the resulting polyanion represents a section of the rutile structure type. Ag2TeO4 shows diamagnetic and insulating behaviour, it decomposes at 560 °C into Ag2TeO3 and oxygen. 相似文献
2.
The crystal structures of the title compounds were solved using the single-crystal X-ray diffraction technique. At room temperature CsKSO4Te(OH)6 was found to crystallize in the monoclinic system with Pn space group and lattice parameters: ; ; ; β=106.53(2)°; ; Z=4 and . The structural refinement has led to a reliability factor of R1=0.0284 (wR2=0.064) for 7577 independent reflections. Rb1.25K0.75SO4Te(OH)6 material possesses a monoclinic structure with space group P21/a and cell parameters: ; ; ; β=106.860(10)°; ; Z=4 and . The residuals are R1=0.0297 and wR2=0.0776 for 3336 independent reflections. The main interest of these structures is the presence of two different and independent anionic groups (TeO66− and SO42−) in the same crystal.Complex impedance measurements (Z*=Z′—iZ″) have been undertaken in the frequency and temperature ranges 20-106 Hz and 400-600 K, respectively. The dielectric relaxation is studied in the complex modulus formalism M*. 相似文献
3.
Reaction of Telluriumhexafluoride and Trimethylamine, Structures of the TeF5? and SeF5? Anions The reaction of TeF6 and (CH3)3N is of the redox kind, resulting in reduction of tellurium: X-ray single crystal analysis reveals the compounds (CH3)2N? CH2? N(CH3)2+TeF5? and [(CH3)3NH+]5(TeF5?)3(HF2?)2. By comparison with published data it can be shown that this mixture is identical to previously published [(CH3)3N]2TeF6. The latter was supposed to be one of the few examples of tellurium in a coordination state of eight. (CH3)4N+TeF5? and (CH3)4N4SeF5? are obtained and their structure is investigated by single crystal x-ray methods also. The anions SF5?, SeF5? and TeF5? are discussed in terms of weak interactions. 相似文献
4.
Simona Rada Maria Bosca Eugen Culea Marius Rada Viorel Dan Vistrian Maties 《Structural chemistry》2009,20(5):801-805
Glasses in the system xGd2O3 · (100 − x)[0.7TeO2 · 0.3V2O5] with 0 ≤ x ≤20 mol% have been prepared from melt quenching method. Influence of gadolinium ions on structural behavior in vanadate–tellurate
glasses has been investigated using FTIR spectroscopy, X-ray diffraction (XRD), and magnetic susceptibility measurements.
The structural changes have been analyzed with increasing rare earth concentration. The structural changes, as recognized
by analyzing band shapes of XRD and FTIR spectra, revealed that Gd2O3 causes a higher extent of network polymerization as far as 20 mol%. The structure of the heat-treated glasses was found to
consist mainly of the Te2V2O9 crystalline phase. These vitreous systems were investigated by magnetic susceptibility measurements. From the paramagnetic
susceptibility χ was calculated at different temperature and from the 1/χ(T) graph, the Curie temperature of the glass has been evaluated. Magnetic susceptibility data show the presence of small antiferromagnetic
interactions between the Gd+3 ions. 相似文献
5.
Matthias Weil 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(8):712-716
The title compound, dimercury(II) divanadium(V) ditellurium(IV) undecaoxide, Hg2V2Te2O11, is a new representative within the family of divalent oxovanadato(V)tellurates(IV). The anionic framework is made up of disphenoidal [TeO4] polyhedra that are linked by corner‐sharing to two neighbouring pyrovanadate units, resulting in chains of six‐membered rings propagating parallel to [10]. The bridging O atom of the pyrovanadate unit is located on an inversion centre, leading to a staggered conformation and a linear V—O—V angle between the two [VO4] tetrahedra. The anionic chains are connected by interjacent six‐coordinate Hg2+ cations into a three‐dimensional framework. The 5s2 lone electron pair of the TeIV atom is stereochemically active and protrudes into the free space of the chain links. 相似文献
6.
The temperature and concentration dependences of the electrical conductance of aqueous solutions of sulfuric acid, selenic acid, and potassium tellurate were studied. The coefficients of the corresponding empirical equations were determined, and the values of equivalent conductances of the anions were evaluated at infinite dilution at the experimental temperatures. The values of the coefficients in the Fuoss and Onsager equation were evaluated for the three electrolytes at 298 K. The values of the molecular and ionic coefficients of self-diffusion at infinite dilution were calculated in the temperature range 288–318 K. The change of the translational energy Δ E∘tr. of water molecules in the ionic hydration sphere was determined. The number of water molecules participating in the ionic hydration sphere at 298 K and the changes of Gibbs free energy, enthalpy, and entropy of activation of ionic conductance were calculated. The results obtained were interpreted according to the Samoylov’s theory of positive and negative hydration of ions. The differences observed in the temperature dependences of the mentioned parameters were explained in terms of the different radii and hydration numbers of the ions. 相似文献
7.
The temperature and concentration dependences of the electroconductivity of aqueous solutions of sulfuric and selenic acids and potassium tellurate are studied. Coefficients of empirical equations that describe these dependences are determined. Activation energies for electroconduction of these solutions as a function of concentration are calculated and it is assumed that these are linked with the hydration degree of ions and the destruction of the quasi-crystalline tetrahedral water cage. 相似文献
8.
The extensive investigation of 3d transition metal chalcogenide (sulphides, selenides, tellurides) precatalysts has shown that they transform into (oxyhydr)oxides during the oxygen evolution reaction (OER) and likely during industrial hydrogen evolution reaction (HER) conditions, as predicted by their Pourbaix diagrams. The phases formed from chalcogenide precatalysts are often more active, due to anion leaching induced effects. But are chalcogenides suitable to be used sacrificially, are they abundant, cheap, and non-toxic enough? Is their unique chemical nature really required? This review answers these questions by discussing the role of chalcogenides in the reconstruction/transformation process. Furthermore, it examines the role of remaining traces of chalcogenates (sulphate, selenate) that were recently shown to improve the OER activity and can break the 1OH/1OOH scaling relations. 相似文献
9.
过渡金属氧化物(MO)可以显著影响聚磷酸铵(APP)的热分解过程,进而改善APP复配膨胀阻燃聚合物材料的阻燃效率。将ZnO、Fe2O3、TiO2掺入到APP中,采用热失重分析(TGA)、X射线光电子能谱(XPS)和X射线衍射分析(XRD),考察了3种MO对APP热分解行为的影响,分析了相互作用过程中金属原子和磷原子化学结合状态的变化以及高温热分解产物的物相结构。TGA和XPS图谱分析结果表明,MO可降低APP的起始热分解温度,并催化APP释放NH3和H2O,而在热分解后期由于金属磷酸盐的形成可显著增加APP的高温残留量。3种MO催化APP热分解脱NH3和H2O的活性由大到小的顺序是:ZnO>Fe2O3>TiO2,而对APP凝聚相热分解P-O产物的交联能力从大到小的顺序为:Fe2O3>ZnO>TiO2。XRD结果显示,ZnO在高温下与APP反应生成了Zn(PO3)2晶体,而Fe2O3和TiO2与APP反应分别生成了Fe4(P2O7)3和TiP2O7晶体。 相似文献
10.
In dissociation experiments of H2O2 under shock wave conditions, the spectra of H2O2 and HO2 have been observed in the UV at 2200 ≤ 2800 Å. By the use of these spectra the H2O2 decomposition in the presence of H2 and CO at 870 ≤ T ≤ 1000°K has been analyzed. It was found that in this temperature range, in contrast to low temperature behavior, reactions of H atoms with H2O2 and with HO2 are equally important. The rate of the reaction H + H2O2 ← HO2 + H2 was estimated in comparison with the rate of the reaction between H and HO2. Good agreement between calculated and measured concentration profiles of HO2 and H2O2 was obtained. 相似文献
11.
The solubilities of the systems CeO2-SeO2-H2O and Ce2O3-SeO2-H2O were studied at 100°C. The field of crystallization of Ce(SeO3)2 was established in the system CeO2-SeO2-H2O, and fields of crystallization of Ce2(SeO3)3 and Ce2(SeO3)3H2SeO3 were established in the system Ce2O3-SeO2-H2O. The compound obtained were identified by means of chemical, X-ray and derivatograph analysis. The mechanism of thermal
dissociation of Ce(SeO3)2, Ce2(SeO3)3 and Ce2(SeO3)3·H2SeO3 was studied.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
12.
DTA and TG studies in air were carried out for hydrothermally prepared rhombohedral double carbonates of dolomite type, CaMg(CO3)2, CaMn(CO3)2, CdMg(CO3)2, CdMn(CO3)2 and CdZn(CO3)2. The solid decomposition products in air have been compared to those obtained under hydrothermal conditions with CO2 pressure. The dolomite [CaMg(CO3)2] decomposes in two stages both in air as well as under high CO2 pressure. The other carbonates studied, follow a single stage decomposition in air and a two stage decomposition under hydrothermal condition. In air, the manganese containing carbonates CaMn(CO3)2 and CdMn(CO3)2, decompose to form mixed oxides of CaMnO3 and CdMnO3 respectively, while CdMg(CO3)2 and CdZn(CO3)2 decompose to their respective two mono oxides.
Zusammenfassung Mittels DTA und TG in Luft werden die hydrothermisch hergestellten rhomboedrischen Doppelkarbonate (Dolomittyp) CaMg(CO3)2, CaMn(CO3)2, CdMg(CO3)2, CdMn(CO3)2 und CdZn(CO3)2 untersucht. Die in Luft erhaltenen festen Zersetzungsprodukte wurden mit denen verglichen, die unter hydrothermischen Bedingungen mit CO2-Druck entstehen. Dolomit zersetzt sich sowohl in Luft als auch unter hohem CO2-Druck in zwei Schritten. Die übrigen untersuchten Karbonate zersetzen sich in Luft in einem, unter hydrothermischen Bedingungen in zwei Schritten. In Luft zersetzen sich die magnesiumhaltigen Karbonate CaMn(CO3)2 und CdMn(CO3)2 unter Bildung der Mischoxide CaMnO3 und CdMnO3, während aus CdMg(CO3)2 und CdZn(CO3)2 jeweils die entsprechenden beiden Monoxide entstehen.相似文献
13.
An influence of inorganic compounds (Fe2O3, ZnO, PbO, CaCO3 and K2CO3) on the blast furnace coke thermal oxidation in the air and in the CO2atmosphere was investigated by means of thermal analysis. A catalytic effect showed itself at the oxidation in the air, especially
with PbO and K2CO3. These compounds bring the oxidation starting temperature and activation energy down and increase the reaction rate constant
most distinctly. The PbO and K2CO3 actions differ in their mechanisms. K2CO3 accelerates particularly the amorphous coke fractions oxidation. In the CO2 atmosphere an important catalytic effect occurred only with K2CO3. The PbO catalytic influence is less distinct.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
14.
Six inorganic compounds, i.e., Na2CO3, NaOH, NaCl, Na2SiO3, TiO2 and HZSM-5, have been investigated with regard to their catalytic effects on pyrolysis of three biomass species, i.e., pine wood, cotton stalk and fir wood by thermal analysis experiments. The results show that Na2CO3, NaOH, Na2SiO3 and NaCl made devolatilization occur at lower temperature regions in the pyrolysis of the three kinds of biomass, whereas TiO2 and HZSM-5 made that occur at higher temperature regions in the pyrolysis of cotton stalk and had no obvious effects on pyrolysis temperatures of pine wood and fir wood. The basic catalysts NaOH, Na2CO3 and Na2SiO3 decreased the maximum weight loss rates while NaCl and HZSM-5 increased them and TiO2 had no obvious effects on them. The four sodium compounds made pyrolysis of the three kinds of biomass more exothermic, which might be due to more char formation, whereas TiO2 and HZSM-5 had minor effects on reaction heat. The catalytic effects in all aspects were roughly correlated with one another and their relationship with the basicity and acidity of the catalysts were preliminarily described and analyzed. 相似文献
15.
A. I. Kazakov Yu. I. Rubtsov L. P. Andrienko G. B. Manelis 《Russian Chemical Bulletin》1998,47(3):379-385
The kinetic regularities of the heat release during the thermal decomposition of liquid NH4N(NO2)2 at 102.4–138.9 °C were studied. Kinetic data for decomposition of different forms of dinitramide and the influence of water
on the rate of decomposition of NH4N(NO2)2 show that the contributions of the decomposition of N(NO2)2
− and HN(NO2)2 to the initial decomposition rate of the reaction at temperatures about 100 °C are approximately equal. The decomposition
has an autocatalytic character. The analysis of the effect of additives of HNO3 solutions and the dependence of the autocatalytic reaction rate constant on the gas volume in the system shows that the self-acceleration
is due to an increase in the acidity of the NH4N(NO2)2 melt owing to the accumulation of HNO3 and the corresponding increase in the contribution of the HN(NO2)2 decomposition to the overall rate. The self-acceleration ceases due to the accumulation of NO3
− ions decreasing the equilibrium concentration of HN(NO2)2 in the melt.
For Part 2, see Ref. 1.
Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 395–401 March 1998. 相似文献
16.
17.
过渡金属氧化物(MO)可以显著影响聚磷酸铵(APP)的热分解过程, 进而改善APP复配膨胀阻燃聚合物材料的阻燃效率。将ZnO、Fe2O3、TiO2掺入到APP中, 采用热失重分析(TGA)、X射线光电子能谱(XPS)和X射线衍射分析(XRD), 考察了3种MO对APP热分解行为的影响, 分析了相互作用过程中金属原子和磷原子化学结合状态的变化以及高温热分解产物的物相结构。TGA和XPS图谱分析结果表明, MO可降低APP的起始热分解温度, 并催化APP释放NH3和H2O, 而在热分解后期由于金属磷酸盐的形成可显著增加APP的高温残留量。3种MO催化APP热分解脱NH3和H2O的活性由大到小的顺序是:ZnO>Fe2O3>TiO2, 而对APP凝聚相热分解P-O产物的交联能力从大到小的顺序为:Fe2O3>ZnO>TiO2。XRD结果显示, ZnO在高温下与APP反应生成了Zn(PO3)2晶体, 而Fe2O3和TiO2与APP反应分别生成了Fe4(P2O7)3和TiP2O7晶体。 相似文献
18.
H. R. C. Ouriques M. F. S. Trindade M. M. Conceiçăo S Prasad P. F. A. Filho A. G. Souza 《Journal of Thermal Analysis and Calorimetry》2004,75(2):569-576
The thermogravimetric curves of di-n-propylammonium, di-iso-propylammonium, di-n-butylammonium and di-iso-butylammonium chlorides showed similar profiles, characterized by mass loss in only one stage, corresponding to decomposition
of compounds. The following thermal stability order was obtained: [Bu2
nNH2]Cl>[Pr2
nNH2]Cl>[Pr2
iNH2]Cl>[Bu2
iNH2]Cl. The values of activation energy for non-isothermal data obtained by Ozawa and Coats-Redfern integral methods were in
agreement and stability order obtained by thermogravimetry were reproduced in both methods. The decomposition reactions of
[Pr2
nNH2]Cl, [Pr2
iNH2]Cl and [Bu2
iNH2]Cl were better described by A3 model and [Bu2
nNH2]Cl by A2 model.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
19.
Changyuan Lu Side Yao Wenfeng Wang Yongpeng Tong Weizhen Lin Tingwen Rong Nianyun Lin 《中国科学B辑(英文版)》1998,41(3):259-265
Fullerols of C60 and of C70 [C60(OH)n, C70(OH)m], water-soluble fullerene derivatives, unlike some other fullerene derivatives (such as C60 (C4H6O), C60 (C3H7N) and C60 [C(COOEt)2]x), do not result in excited triplet state but in ionization via monophotonic process in aqueous solutions with 248 nm laser.
The quantum yields of formation of hydrated electron (Φe
−) are determined to be 0.08 and 0.11 for fullerols of C60 and of C70 respectively at room temperature (ca. 15°C) with KI solution used as reference. By laser flash photolysis and oxidation of
sulfate radical anion SO4
−, the fullerol radical cation or neutral radical of C60 is confirmed to be existent and the transient absorption spectra of fullerol radical cation of C70 are observed for the first time.
Project supported by the National Natural Science Foundation of China 相似文献
20.
由摩尔比分别为1:2和1:8的NiCl2·6H2O和Na2B4O7·10H2O作为反应物, 合成两种非晶态镍硼酸盐, 同时通过水热法合成β-Ni(OH)2. 化学分析和热重-微商热重法(TG-DTG)分析结果确定两种非晶态镍硼酸盐的分子组成分别为NiO·0.8B2O3·4.5H2O和NiO·B2O3·3H2O. 激光拉曼(Raman)实验结果表明镍硼酸盐样品中主要存在的硼氧阴离子为B3O3(OH)52-和B2O(OH)62-. 同步辐射扩展X射线吸收精细结构(EXAFS)方法对样品进行结构解析, 通过数据拟合给出样品中Ni 原子周围近邻配位原子种类、配位数以及原子间距离. 用不同晶体结构作为标准对两种非晶态镍硼酸盐进行拟合的结果表明, 样品中Ni 原子周围局域结构与Ni3B2O6晶体(ICSD No.31387)中的吻合较好. Ni 原子周围配位原子为O、B和Ni, 对于NiO·0.8B2O3·4.5H2O, 配位数分别为5.7、3.8和3.8, 配位距离分别为0.208、0.263 和0.311 nm; 对于NiO·B2O3·3H2O, 配位数分别为6.0、4.0 和4.0, 配位距离分别为0.207、0.262和0.310 nm. 相似文献