共查询到19条相似文献,搜索用时 62 毫秒
1.
应用热力学特性函数、齐次函数定理和勒让德变换等概念和方法从理论上探讨了热力学公式RTlnKco=ΔrGmo(T,co)在推导和应用方面的问题。严格的数学论证表明该式是背离热力学原理的,它近似地适用于液相,但应用于气相则可能产生较大偏差。 相似文献
2.
A series of single-phase LixNi0.8-yCo0.2ZnyOp(0.96 ≤x≤ 1.10, 0 ≤y≤ 0.05, 2 ≤p≤ 2(1+y) ) (different in the y values) were synthesized by a two-step solid state reaction method, in which LiOH·H2O, Zn-doped spherical Ni(OH)2 and Co2O3 were used as the precursors. The ICP-AES analyses proved that the Zn-doped compounds synthesized had the nonstoichiometric form. The results of the XRD, SEM identified that the uniform particles of the as-prepared materials having a good layered structure were fine, narrowly distributed and well crystallized. The electrochemical performance test was carried out and the results showed that the as-prepared Zn-doped materials had not only a high capacity, but also a better cycling stability characterization than the un-doped one. The Li1.06Ni0.75Co0.22Zn0.03O2.03 material has an initial reversible capacity as high as 160.5mAh·g-1; and a first discharge efficiency 89.2%, and exhibits satisfactory cyclic stability with 90% retainable capacity after 50 cycles. 相似文献
3.
合成了Zr1-xMxWMoO8-x/2(M=Er,Tm,Yb,Sc,In,Ga,Al)和Zr1-xMxW2O8-x/2(M=Eu,Er,Yb,Sc,In,Ga,Al)2个系列的固溶体,前者具有β-ZrW2O8结构类型(简称β相);后者具有α-ZrW2O8结构类型(简称α相)。建立了相和相的晶胞参数与M3+离子浓度的Vegard方程,测定了上述固溶体的固溶度。讨论了M3+离子的化学性质与Vegard斜率SV的关系。分析了α相的SαA与β相的SβA的关系;揭示了α-Zr1-xMxW2O8-x/2晶格中2[WO4]四面体对的取向有序程度对晶格畸变的贡献。提出上述固溶体的晶胞参数随溶质浓度增加而减小,主要是由于氧空位缺陷相互作用的结果。 相似文献
4.
钙钛矿型LaxSr1-xNi1-yCoyO3光电催化活性研究 总被引:8,自引:0,他引:8
用甘氨酸-硝酸盐燃烧合成法, 制备LaxSr1-xNi1-yCoyO3复合氧化物的陶瓷粉末, 对钙钛矿氧化物进行了XRD结构分析. 在通氧或不通氧下测试氧还原和氧析出的循环伏安曲线. 结果表明: 该氧电极具有双功能催化特性, 但不完全可逆. 利用汞灯作为激发光源, 进行几种水溶性染料和五种混合染料光解实验, 利用紫外-可见、红外以及人工神经网络光度法研究LaxSr1-xNi1-yCoyO3的催化性能. 结果表明: LaxSr1-xNi1-yCoyO3 (x=0.7, 0.9, 1; y=0.3, 0.75)复合氧化物都具有较强光催化特性; LaxSr1-xNi1-yCoyO3的光催化活性高于LaxSr1-xNiO3, 这与B位离子(Ni2—, Co2-)的电子构型有关; Co2+的加入可使LaxSr1-xNiO3的光催化活性有所提高. 相似文献
5.
利用溶胶-凝胶分配理论对氢键溶液的模型体系进行研究, 给出了凝胶点后氢键网络中各结构参数的计算方案, 并进行相应的数值计算. 结果表明, 因受体基团本身的性质及两类质子受体基团的数量比不同, 受体基团的竞争作用对网络结构有明显影响, 这提供了控制氢键网络结构特征的可能方法. 相似文献
6.
7.
采用高温固相法制备了4种高纯度晶相组成的LixZryOz三元化合物,研究了焙烧温度、时间、反应物的种类和初始反应物物质的量比对产物组成的影响,进一步用XRD、SEM及BET分析方法对产物的晶相结构、表面形貌及比表面积进行了表征.实验结果表明,Li2CO3与ZrO2在适当条件下可以合成得到单斜相Li3ZrO3;以LiOH替代Li2CO3,在适当条件下可以分别合成得到四方相Li2ZrO3和三斜/单斜相Li6Zr2O7;进一步以Zr(NO3)4·5H2O代替Zr02,可将单斜相Li6Zr2O7的制备时间由96 h缩短至24 h.SEM照片显示产物硬团聚明显,粒径分布在1~10μm间,BET分析表明样品比表面积处于1.0~9.0 m2·g-1间分布,反应过程中锂的过量以及长时间高温焙烧是引起产物粒径长大和产生硬团聚的主要原因. 相似文献
8.
采用改进的水热法成功合成了单分散的纯相锶铁氧体纳米片。借助DLS、XRD、FTIR、SEM、EDS和VSM等分析测试手段对SrFe12O19铁氧体粉体的粒度、结构、形貌和磁性能进行表征。研究结果表明,在240℃保温5 h,物质的量之比nFe3+/nSr2+(RF/S)和nOH-/nNO-(RO/N)分别为5和2时,所得产物为单分散的纯相六角SrFe12O19铁氧体纳米片。随着RF/S和RO/N的变化,合成样品中有少量SrCO3和Fe2O3杂相存在,这主要与反应条件和离子比例有关。磁性能测试结果显示,所得纯相的六角SrF12O19铁氧体纳米片具有优异的磁性能,其饱和磁化强度和矫顽力分别达到60.91 emu·g-1和94.83 kA·m-1,使其在医疗、催化和生物等高技术领域具有潜在的应用。 相似文献
9.
采用改进的水热法成功合成了单分散的纯相锶铁氧体纳米片。借助DLS、XRD、FTIR、SEM、EDS和VSM等分析测试手段对SrFe12O19铁氧体粉体的粒度、结构、形貌和磁性能进行表征。研究结果表明,在240℃保温5 h,物质的量之比nFe3+/nSr2+(RF/S)和nOH-/nNO3-(RO/N)分别为5和2时,所得产物为单分散的纯相六角SrFe12O19铁氧体纳米片。随着RF/S和RO/N的变化,合成样品中有少量SrCO3和Fe2O3杂相存在,这主要与反应条件和离子比例有关。磁性能测试结果显示,所得纯相的六角SrF12O19铁氧体纳米片具有优异的磁性能,其饱和磁化强度和矫顽力分别达到60.91 emu·g-1和94.83 kA·m-1,使其在医疗、催化和生物等高技术领域具有潜在的应用。 相似文献
10.
纳米钙钛矿LaxSr1-xFe1-yCoyO3复合氧化物的制备和表征 总被引:1,自引:0,他引:1
用甘氨酸-硝酸盐燃烧合成法,制备LaxSr1-xFe1-yCoyO3复合氧化物的陶瓷粉末,对该钙钛矿型氧化物进行了XRD、IR、紫外漫反射光谱及循环伏安曲线分析。结果表明:该复合氧化物粉体平均晶粒为15.3~29.8 nm,为立方和正交晶系。该氧电极具有双功能催化特性,但不完全可逆。对水溶液染料进行光解实验,利用紫外-可见、人工神经网络光度法研究LaxSr1-xFe1-yCoyO3的催化性能。结果表明:CO2+的加入可使LaxSr1-xFeO3的光催化活性有所提高,B位离子(Fe3+,CO2+)改变与加入,使LaxSr1-xFe1-yCoyO3(x=0.7,0.3;y=0.3,0.9,1)光催化活性高于LaxSr1-xFeO3。同时,对5种染料进行紫外光解,在0.75 h,脱色率大于91%,并为动力学一级反应。 相似文献
11.
Solvent extraction studies have been made on some metals: In/III/-Tl/III/ and Hg/II/-Cd/II/-Co/II/, from ammonium thiocyanate solutions by dialkyl sulphoxides. Separation of these metals from one another can be achieved by suitable choice of the extracted conditions. The nature of the extractable metal species has been elucidated. 相似文献
12.
Synthesis of chlorobis/β-diketonato/oxotechnetium/V/ and tris/β-diketonato/technetium/III/ complexes
K. Hashimoto Y. Yamada T. Omori K. Yoshihara 《Journal of Radioanalytical and Nuclear Chemistry》1989,135(3):187-197
Chlorobis/-diketonato/ oxotechnetium/V/ complexes [TcOCl/-dik/2, -diketone=acetylacetone, benzoylacetone and dibenzoylmethane] were newly synthesized using macroamount of99Tc. These complexes were further separated into geometrical isomers. Furthermore, an improvement of the yields for the syntheses of tris/-dike-tonato/technetium/III/ complexes [Tc/-dik/3, -diketone=acetylacetone, benzoylacetone and 2-thenoyltrifluoroacetone] was examined using Tc/III/-thiourea complexes as a starting material. 相似文献
13.
The crystal structure of trisodium monophosphate hemihydrate was determined. The space group is and a unit cell contains eight formula units. The unit cell dimensions of are a = 9.631(3), b = 5.416(2), c = 16.938(8) Å, β = 102.60(5)°. The final R value is 0.027 for a set of 1430 independent reflections. This atomic arrangement is mainly a three-dimensional network of distorted NaO6 octahedra. The hydrogen bonding scheme is given. 相似文献
14.
Summary Single reverse water-gas shift (RWGS) and dehydrogenation of propane with CO2(DH-CO2) reactions in the presence and absence of the CrOx/SiO2 catalyst have been studied between 673 and 873 K. It was found that the CrOx/SiO2 catalyst is active both in the dehydrogenation of propane and in the RWGS reactions. The obtained results suggest that the
dehydrogenation of propane to propene in the presence of CO2on CrOx/SiO2can be facilitated by the RWGS reaction.</o:p> 相似文献
15.
Summary CexTi1-xO2 and H3PW12O40/CexTi1-xO2 catalysts were prepared using a sol-gel method, and applied to the direct synthesis of dimethyl carbonate from methanol and
carbon dioxide. H3PW12O40/CexTi1-xO2 showed a better catalytic performance than the corresponding CexTi1-xO2, due to the bifunctional catalysis of Br?nsted acid sites (provided by H3PW12O40) and base sites (provided by CexTi1-xO2). H3PW12O40/Ce0.1Ti0.9O2 showed the highest catalytic performance among the H3PW12O40/CexTi1-xO2 catalysts. 相似文献
16.
Ninh Nguyen Jacques Choisnet Maryvonne Hervieu Bernard Raveau 《Journal of solid state chemistry》1981,39(1):120-127
Oxygen defect K2NiF4-type oxides have been synthesized for a wide composition range: 0 ≤ x ≤ 1.34. From the X-ray and electron diffraction study three domains have been characterized: orthorhombic compounds with La2CuO4 structure for 0 ≤ x < 0.10, tetragonal oxides similar to LaSrCuO4 for 0.10 ≤ x < 1 and several superstructures derived from the tetragonal cell ( with n = 3, 4, 4.5, 5, 6) for 1 ≤ x ≤ 1.34. The compounds corresponding to 0 < x < 1 differ from the other oxides in that they are characterized by the presence of copper with two oxidation states: + 2 and + 3. A model structure for La0.8Sr1.2CuλO3.4, in which copper has only the + 2 oxidation state, and for which the actual cell is tegragonal—a = 18.804 Å and c = 12.94 Å—has been established. The particular structural evolution of these compounds is discussed in terms of a competition between the capability of Cu(II) to be oxidized to Cu(III) and the ordering of oxygen vacancies. 相似文献
17.
Grisel Corro Odilón Vázquez-Cuchillo Fortino Ba?uelos 《Reaction Kinetics and Catalysis Letters》2005,87(1):171-175
Summary A strong promoting effect of the presence of C3H8or C3H6was determined for the combustion of CH4in excess oxygen, over pre-sulfated 1%Pt/g-Al2O3and pre-sulfated 1%Pt-2%Sn/g-Al2O3catalysts.</o:p> 相似文献
18.
P.P. Edwards R.G. Egdell I. Fragala J.B. Goodenough M.R. Harrison A.F. Orchard E.G. Scott 《Journal of solid state chemistry》1984,54(2):127-135
HeI-excited valence-band ultraviolet photoelectron spectra and MgKα-excited Ti-2p X-ray photoelectron spectra are reported for the spinel materials LiTi2O4 and . The presence of a Fermi edge in the ultraviolet photoelectron spectrum of LiTi2O4 confirms the metallic nature of this material, although the measured density of states at the Fermi energy is much lower than that expected from an independent-electron interpretation of the magnetic susceptibility. This difference is attributed to a strong interaction of the conduction electrons with the lattice vibrations. The localization of conduction electrons that occurs in the final state in the Ti-2p X-ray photoelectron spectrum of LiTi2O4 is attributed to a Coulomb interaction with a core hole. 相似文献
19.
Mónica Martos Beatriz Julián Eloisa Cordoncillo 《Journal of solid state chemistry》2007,180(2):679-687
Doped-rutile has been traditionally used in ceramic pigments for its intense optical properties. In this paper, we compare the classical ceramic synthesis of Ti1−2xNbxNixO2−x/2 system with the sol-gel methodology, which allows a reduction of the anatase-rutile transformation temperature. The composition was optimised in order to obtain a unique rutile phase with the minimum amount of pollutant Ni(II) and enhanced chromatic coordinates. Incorporation of the doping ions in the rutile structure was corroborated by XRD and Rietveld refinements. The species responsible for the colour mechanism were studied by different techniques. UV-VIS spectroscopy showed the characteristic features of Ni2+ ions, whose existence was corroborated by EPR and magnetic measurements. From these results, (Ni,Nb)doped-TiO2 powder samples can be now shaped as thin films, monoliths, etc. by using sol-gel methodology without modifying their properties. This study introduces new possibilities of coloured TiO2-based solid solutions in new combined advanced applications (colouring agent and photocatalyst, etc.). 相似文献