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31.
M. Slavík J. Šedlbauer K. Ballerat-Busserolles V. Majer 《Journal of solution chemistry》2007,36(1):107-134
The heat capacities of aqueous solutions of acetone, 2,5-hexanedione, diethyl ether, 1,2-dimethoxyethane, benzyl alcohol and
cyclohexanol at concentrations of 0.1 to 1.0 mol⋅kg−1 were determined at temperatures of 298.15, 423.15, 473.15 and 523.15 K and pressures up to 28 MPa. The measurements were
performed at ambient conditions using the commercial Picker differential flow calorimeter and at high temperatures and pressures
with a customized Picker type calorimeter constructed at the Blaise Pascal University, Clermont-Ferrand. Standard molar heat
capacities were obtained by weighted extrapolation to the infinite dilution limit. The contributions of –CO–, –O– and –OH
groups to the standard molar volume and standard molar heat capacity were determined from the newly determined and literature
data. The variation of the three oxygen-containing group contributions with temperature and molecular structure is examined
qualitatively. 相似文献
32.
研究了无水硫化钠与对二氯苯(以N-甲基吡咯烷酮为溶剂)合成聚苯硫醚反应的宏观动力学,该反应是一个小分子缩合串联自缩聚的过程,通过测定不同反应聚合体系中氯化钠的徨成率和硫化内的转化率,建立了该反应的宏观动力学方程:1/(1-PNaCl+PNa2s)=C0Kt+1;并计算得到220、250℃的表观反应速率为4.5×10^-4和3.0×10^-3kg/(mol.s),表观活化能为134kJ/mol。 相似文献
33.
Luca Bernazzani Maria Rita Carosi Celia Duce Paolo Gianni Vincenzo Mollica 《Journal of solution chemistry》2006,35(11):1567-1585
Excess molar volumes, V
m
E, over the whole composition range for binary mixtures of 1-butanol, 2-butanol, and 2-methyl-2-propanol + 1-octanol, or 2-octanol, or di-n-butyl ether, or n-hexylacetate were determined at 298.15 K from density measurements carried out with a vibrating-tube densimeter. Small V
m
E values, both positive and negative, are displayed by mixtures containing 1- or 2-octanol, whereas positive and larger values are always found for mixtures containing dibutyl ether and hexylacetate. These results can be justified in terms of H-bonding interactions and/or steric hindrance due to the branched alkyl chains. Partial molar volumes at infinite dilution of the isomeric butanols in the C8 compounds were also calculated from the apparent molar volumes in dilute solution. The solute-solvent interactions and the effects of the local organisation of the solvent around the butanol molecules were discussed using the void and cavity volumes as different estimates of the intrinsic volume of the molecules. The volumetric behavior of butanols seems to be determined by the solute-solvent interactions rather than packaging effects. 相似文献
34.
Martin Kirchner Walter Schnelle Frank R. Wagner Rüdiger Kniep Rainer Niewa 《无机化学与普通化学杂志》2005,631(8):1477-1486
Single phase powders of (A19N7)[In4]2 (A = Ca, Sr) and (Ca4N)[In2] were prepared by reaction of melt beads of the metallic components with nitrogen. The crystal structure of (Ca19N7)[In4]2 was refined based on neutron and X‐ray powder diffraction data. The crystal structure of (Sr19N7)[In4]2 was solved from the X‐ray powder pattern. The structure refinements in combination with results from chemical analyses ascertain the compositions. The compounds (A19N7)[In4]2 (A = Ca, Sr) are isotypes of (Ca19N7)[Ag4]2; (Ca19N7)[In4]2 is probably identical to the earlier reported (Ca18.5N7)[In4]2. The crystal structure of the isotypes (A19N7)[In4]2 (A = Ca, Sr; cubic, , Ca: a = 1471.65(3) pm; Sr: a = 1561.0(1) pm) contains isolated [In4] tetrahedra embedded in a framework of edge‐ and vertex‐sharing (A6N) octahedra. Six of these octahedra are condensed by edge‐sharing around one central A2+ ion to form “superoctahedra” (A19N6) which are connected three‐dimensionally via further octahedra by corner‐sharing. The crystal structure of (Ca4N)[In2] (tetragonal, I41/amd, a = 491.14(4) pm, c = 2907.7(3) pm) consists of alternating layers of perovskite type slabs of vertex‐sharing octahedra (Ca2Ca4/2N) and parallel arranged infinite zigzag chains equation/tex2gif-stack-1.gif[In2]. In the sense of Zintl‐type counting the compounds (A2+)19(N3?)7[(In2.125?)4]2 present an electron excess, (Ca2+)4(N3?)[(In2.5?)2] is electron deficient. Metallic properties are supported by electrical resistivity and magnetic susceptibility measurements. The analysis of the electronic structures gives evidence for the existence of homoatomic interactions In–In and significant heteroatomic metal–metal interactions Ca–In which favor the deviations of the title compounds from the (8 – N) rule. 相似文献
35.
36.
The cubic inverse Perovskites (Eu3O)In and (Eu3O)Sn were prepared from the metals and Eu2O3 or SnO2, respectively. For (Eu3O)In the crystal structure analysis was performed on single crystal X‐ray diffraction data (space group , a = 512.79(3) pm, Z = 1, Rgt(F) = 0.022, wR(F2) = 0.044). The data indicated full occupancy on all sites and a fully ordered structure. According to magnetic susceptibility measurements and X‐ray absorption spectroscopic data at the Eu LIII edge both compounds contain europium in the 4f7 (Eu2+) electronic state. (Eu3O)In orders ferromagnetically at 185(5) K, (Eu3O)Sn shows antiferromagnetic order at 31.4(2) K. Both compounds behave as metallic conductors in electrical resistivity measurements. However, (Eu3O)In may be classified a metal, while (Eu3O)Sn is more likely a heavily doped degenerated semiconductor or semimetal according to the absolute values of the resistivity. 相似文献
37.
By means of the addition of Ba into the Bi-Ca-Sr-Cu-O 2122 system, a series of Bi2CaSr2-xBaxCu2O8+δ (0 ≤ × ≤ 2) quinary metal oxides were prepared by the citrate route and by the conventional powder reaction method. The samples prepared by the former method have better properties than the latter. It was found that 5 was not equal to zero for all of them and that it increased with decreasing Tc. Two phases were indentified in the oxides containing all five metal elements. One is the Bi-Ca-Sr-Cu-O 2122 phase, the other is a new insulating phase which probably contains Bi-Ca-Ba-Cu-O with undetermined stoichiometry. Superconductivity was found in those samples for which × ≤ 1.50 with their Tc onsets between 93–78 K by resistivity measurements. Superconductivity decreased monotonically with increasing x. However, residual resistance was found in those samples for which 1.00 ≤ × ≤ 1.50, The Meissner effect appears in the samples where × ≤ 1.00 with Tc onsets between 88–80 K. For x = 1.75 and 2.00, the samples were semiconductors with resistivities of 6.66 × 102 and 6.96 × 103 Ω cm at 290 K, and activation energies of 0.109, and 0.298 eV, respectively. 相似文献
38.
Rangel Elidiane C. Cruz Nilson C. da Kayama Milton E. Rangel Rita C. C. Marins Nazir Durrant Steven F. 《Plasmas and Polymers》2004,9(1):1-22
Diamond-like carbon (DLC) films were grown from radiofrequency plasmas of acetylene-argon mixtures, at different excitation powers, P. The effects of this parameter on the plasma potential, electron density, electron temperature, and plasma activity were investigated using a Langmuir probe. The mean electron temperature increased from about 0.5 to about 7.0 eV while the mean electron density decreased from about 1.2 × 109 to about 0.2 × 109 cm–3 as P was increased from 25 to 150 W. Both the plasma potential and the plasma activity were found to increase with increasing P. Through actinometric optical emission spectrometry, the relative concentrations of CH, [CH], and H, [H], in the discharge were mapped as a function of the applied power. A rise in [H] and a fall in [CH] with increasing P were observed and are discussed in relation to the plasma characteristics and the subimplantation model. The optical properties of the films were calculated from ultraviolet-visible spectroscopic data; the surface resistivity was measured by the two-point probe method. The optical gap, E
G, and the surface resistivity, s, fall with increasing P. E
G and s are in the ranges of about 2.0–1.3 eV and 1014–1016 /, respectively. The plasma power also influences the film self-bias, V
b, via a linear dependence, and the effect of V
b on ion bombardment during growth is addressed together with variation in the relative densities of sp2 and sp3 bonds in the films as determined by Raman spectroscopy. 相似文献
39.
利用TEM法,对比分析不同测线视电阻率-深度断面图,得出地下岩层含水层的埋藏条件及富水性,初步确定取水井位;再结合区域水文地质条件,对比分析不同测线中单井涌水量的相对大小,最终确定理想井位.以TEM在内蒙古正镶白旗地区地下水勘察中的应用为例,证明了TEM在确定含水层及井位上的有效性. 相似文献
40.
ZAO透明导电纳米薄膜中Al元素分布对其性能的影响 总被引:6,自引:0,他引:6
主要对直流反应磁控溅射法制备ZAO纳米薄膜中Al元素的相对含量进行了分析,对其作了EDS,XRD测试,并研究了Al质量分数与ZAO薄膜的光、电性能的关系·得出ZAO薄膜中成分是均匀的,具有ZnO晶体结构;Al元素的掺杂没有形成新的化合物(Al2O3),Al对Zn的掺杂替换是提高ZAO薄膜导电性能的关键因素,对薄膜在可见光区的透射性影响不大·制备的薄膜最低电阻率为4 5×10-4Ω·cm,可见光透射率达到80%以上· 相似文献