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1.
A series of Ce xPr 1−xO 2−δ mixed oxides were synthesized by a sol–gel method and characterized by Raman, XRD and TPR techniques. The oxidation activity for CO, CH 3OH and CH 4 on these mixed oxides was investigated. When the value x was changed from 1.0 to 0.8, only a cubic phase CeO 2 was observed. The samples were greatly crystallized in the range of the value x from 0.99 to 0.80, which is due to the formation of solid solutions caused by the complete insertion of Pr into the CeO 2 crystal lattices. Raman bands at 465 and 1150 cm −1 in Ce xPr 1−xO 2−δ samples are attributed to the Raman active F 2g mode of CeO 2. The broad band at around 570 cm −1 in the region of 0.3 ≤ x ≤ 0.99 can be linked to oxygen vacancies. The new band at 195 cm −1 may be ascribed to the asymmetric vibration caused by the formation of oxygen vacancies. The TPR profile of Pr 6O 11 shows two reduction peaks and the reduction process is followed: . The reduction temperature of Ce xPr 1−xO 2−δ mixed oxides is lower than those of Pr 6O 11 or CeO 2. TPR results indicate that Ce xPr 1−xO 2−δ mixed oxides have higher redox properties because of the formation of Ce xPr 1−xO 2−δ solid solutions. The presence of the oxygen vacancies favors CO and CH 3OH oxidation, while the activity of CH 4 oxidation is mostly related to reduction temperatures and redox properties. 相似文献
2.
合成了一种新的具有潜在应用价值的非线性光学(NLO)有机材料1-(芘-1-基)-3-(4-二甲氨基苯基)丙烯酮(PMAK),并通过 NMR、IR、MS和元素分析等技术手段进行了表征。 采用溶液Nd:YAG激光技术测定了PMAK的三阶非线性光学性质并确定了相关参数。 纳秒实验结果:折射率 n2=-3.5×10 -17 m 2/W,吸收系数 β=7.0×10 -10 m/W,极化率 χ(3)=2.54×10 -11 esu,分子超极化率 γ=3.44×10 -30 esu;皮秒实验结果: n2=-2.8×10 -18 m 2/W, β=8.3×10 -11 m/W, χ(3)=2.49×10 -12 esu, γ=3.33×10 -31 esu。 相似文献
3.
Since the discovery of superconductivity in Sr 2CuO 2F 2+δ there has been an increased interest in ternary oxide-fluorides. Sr 2CuO 2F 2+δ is prepared via low temperature ( T = 220 °C) reaction routes. Low temperature fluorination induces an interesting structural rearrangement in the parent compound Sr 2CuO 3, which is a one-dimensional material containing linear chains of vertex sharing CuO 4 squares along the crystallographic b axis. Upon fluorination, one oxide is substituted by two fluorides and Cu 2+ becomes octahedrally coordinated by four oxides and two fluorides. The fluorinated compound Sr 2CuO 2F 2+δ displays the T-type structure (La 2CuO 4). Insertion of excess fluorine, δ, also takes place and this fluorine occupies interstitial sites in the T structure. Although the starting material Ca 2CuO 3 is isostructural to Sr 2CuO 3, Ca 2CuO 2F 2+δ displays the T′ (Nd 2CuO 4) structure due to the smaller radius of Ca 2+ compared to that of Sr 2+. The alkaline-earth palladates with the general formula A2PdO3 (A = Ba, Sr) are isostructural with the A2CuO3(A = Ca, Sr) materials. We prepared the Ba2−xSrxPdO3 (x = 0–2) series and performed low temperature fluorination, which led to the synthesis of the series Ba2−xSrxPdO2F2+δ (0 ≤ x ≤ 1.5). All the compounds in the Ba2−xSrxPdO2F2+δ series show T′ structure (Ca2CuO2F2+δ). Similarities and differences with Sr2CuO2F2+δ and Ca2CuO2F2+δ will be discussed. 相似文献
4.
The distribution ratio ( DM) of Pd(II) by the extraction with 2-methyl-8-quinolinol (HMQ) was determined using the supercritical carbon dioxide medium (SF-CO 2) and organic solvent media such as perfluoro-methylcyclohexane, heptane, cyclohexane, carbon tetrachloride and benzene. From experimental results of the slopes of log DM versus pH plot and log DM versus HMQ concentration plot, the extracted species both in the SF-CO 2 extraction (SFE) and the solvent extraction (SE) were determined to be Pd(MQ) 2. The distribution constant of HMQ ( KD,HMQ) in the SFE and SE systems were determined from the dependence of the distribution ratio of HMQ ( DHMQ) on the pH. A linear relationship was observed between log KD,HMQ and the solubility parameter ( δ) of the extraction medium based on the regular solution theory in both the SFE using SF-CO 2 at the pressure of 8.5–40 MPa and the SE systems. The difference in the slope of the log KD,HMQ versus δ plot between the SFE and the SE systems is attributable to the extent of the specific interaction of the solute HMQ with the solvent molecules, i.e. CO 2 molecules and the organic solvent molecules. The DM versus δ plot obtained under a given extraction condition using SF-CO 2 (11–40 MPa) and organic solvents showed clear linearity. The DM obtained using SF-CO 2 at relatively low pressure range from 8.5 to 11 MPa was independent of the pressure and the δ of SF-CO 2, which coincides with the experimental fact that the solubility of Pd(MQ) 2 in the SF-CO 2 at 8.5–11 MPa was practically constant. 相似文献
5.
合成了一个新的非线性光学(NLO)有机材料1-二茂铁基-3-[(9-乙基)咔唑-3-基]丙烯酮(FCAK),并通过NMR、IR、MS和元素分析等技术手段进行了表征。 采用粉末Nd∶YAG激光技术测定了标题化合物的三阶非线性光学性质并确定了相关参数。 激光脉冲为4 ns时,非线性折射率 n2=-3.5×10 -18 m 2/W,非线性吸收系数 β=-2.7×10 -11 m/W,三阶非线性极化率 χ(3)=2.04×10 -12 esu,三阶非线性分子超极化率 γ=1.1×10 -30 esu。 激光脉冲为21 ps时, n2=0.55×10 -18 m 2/W, β=-0.6×10 -11 m/W, χ(3)=3.4×10 -13 esu, γ=0.13×10 -30 esu。 相似文献
6.
Excess molar enthalpies HE and excess molar volumes VE have been measured, as a function of mole fraction x1, at 298.15 K and atmospheric pressure for the five liquid mixtures ( x11,4-C 6H 4F 2 + x2n-C lH 2l+2), l = 7, 8, 10, 12 and 16. In addition, HE and excess molar heat capacities CPE at constant pressure have been determined for the two liquid mixtures ( x1C 6F 6 + x2n-C lH 2l+2), l = 7 and 14, at the same temperature and pressure. The instruments used were flow microcalorimeters of the Picker design (the HE version was equipped with separators) and a vibrating-tube densimeter, respectively. The excess enthalpies of the five difluorobenzene mixtures are all positive and quite large; they increase with increasing chain length l of the n-alkane from HE(x1 = 0.5)/(J mol−1) = 1050 for l = 7 to 1359 for l = 16. The corresponding excess volumes VE are all positive and also increase with increasing l: VE(x1 = 0.5)/(cm3 mol−1) = 0.650 for l = 7 and 1.080 for l = 16. Interestingly, the excess enthalphies of the corresponding mixtures with hexafluorobenzene are only about 5% larger, whereas the excess volumes of (x1C6F6 + x2n-ClH2l+2) are roughly twice as large as those of their counterparts in the series containing 1,4-C6H4F2. Specifically, at 298.15 K HE(x1 = 0.5)/(J mol−1) = 1119 for (x1C6F6 + x2n-C7H16) and 1324 for (x1C6F6 + x2n-C14H30), and for the same mixtures VE(x1 = 0.5)/(cm3 mol−1) = 1.882 and 2.093, respectively. The excess heat capacities for both systems are negative and of about the same magnitude as the excess heat capacities of mixtures of fluorobenzene with the same n-alkanes (Roux et al., 1984): CPE(x1 = 0.5)/(J K−1 mol−1) = −1.18 for (x1C6F6 + x2n-C7H16), and −2.25 for (x1C6F6 + x2n-C14H30). The curve CPE vs. (x1 for x1C6F6 + x2n-C14H30) shows a sort of “hump” for x1 0.5, which is presumed to indicate emerging W-shape composition dependence at lower temperatures. 相似文献
8.
Structure, electronic state and energy of Si nC − and Si nC −2 ( n=1–7) anions have been investigated using the density functional theory. Structural optimization and frequency analysis are performed at the level B3LYP/6-311G(d). The charged-induced structural changes in these anions have been discussed. The strong C–C bond is also favored over C–Si bonds in the Si nC −m anions in comparison with corresponding neutral cluster. Among different Si nC − and Si nC −2 ( n=1–7) anions, Si 3C −, Si 5C − and Si 2C −2 are most stable. Their stability has a decreasing tendency with the increase in the size of these clusters. 相似文献
9.
A UV spectrometric method was developed to determine the molar absorptivity ( C) and formation constant ( Kc) of the association complex of unsubstituted chalcone in cyclohexane, in the concentration range from 4.00·10 −4 to 2.00·10 −2 mol dm −3. The thermodynamic and spectroscopic magnitudes such as Kc and C contribute to the understanding of the physicochemical behavior of several , β-unsaturated carbonylic compounds, of low solubility in water, as it is the case of numerous flavonoids of chemical and biological importance. The studied association complex, formed by two chalcone molecules, is characterized by the constants C (300.8 nm)=4.98·10 4 dm 3 mol −1 cm −1 and Kc=5.58·10 3. The method proposed is convenient for the study of solute–solute molecular associations particularly those due to dipole–dipole interactions. 相似文献
10.
Anion exchange membrane has been investigated in different electrolyte solutions by chronopotentiometry to explore the influence of co-ion and counterion of the exchange group of the membrane, on the transport phenomena. Chloride, nitrate, sulfate and acetate in sodium salts were used as counterions and sodium, potassium, calcium and ammonium in chloride salts were used as co-ions. The membrane showed a potential drop ( E0) in all these electrolytes when a constant current was applied across it, which remained constant for a period less than τ, called the transition time and rose gradually to a maximum ( Emax) value. The parameters such as τ, E0 and Emax and the potential jump (Δ E) and τ and the inflection zone (Δ t) along the time axis have been measured and compared at an applied current density ( I) of 10 mA cm −2 in 10 mM solutions. The values of τ1/2/ zA[ A0] or τ1/2/ zC[ C0], with
or
, E0 and Δ E with
or
(where rA and rC are the ionic radii of counter and co-ions, respectively) have been correlated. Permselectivity ( P) and transference number
of the membrane with respect to each one of the above electrolytes have been evaluated and discussed. 相似文献
11.
Ferrocenyl-1,2-diketones FcCOCOR, 3, [Fc = (C 5H 5)Fe(C 5H 4)] can be prepared by oxidation of acylferrocenes FcCOCH 2R or, more efficiently, by oxidation of the isomeric ketones FcCH 2COR, 2. The ketones 2 are in turn readily synthesized from the salt (FcCH 2PPh 3) +I − via the acylated salts [FcCH(COR)PPh 3] +I −. The haloacylferocenes FcCOCCl x H 3−x ( x = 1, 2, 3, of which the x = 2 example is synthetically equivalent to a diketone) are synthesized by Friedel—Crafts acylation of ferrocene using CCl xH 3−xCOCl/AlCl 3, but the reaction proceeds via two parallel pathways, one giving the normal acyl derivatives FcCOCCl xH 3−x and the other giving the reduced products FcCOCCl x−1H 4−x. Two diketones FcCOCOFc 3b and FcCOCOC 6H 4Ph 3c have been structurally characterised by single-crystal X-ray diffraction. 相似文献
12.
Experimental data on the spatial distribution of the energy deposited around an energetic heavy ion, from 1 MeV proton to 5.9 MeV/n uranium ion, which have been reported in the literature were documented to obtain a scaled radial dose distribution; ( β/ Z*) 2 D( Z*, β, t)=200 (for t=0–1), 200/ t2 (for t=1 tc), and 200 tc/ t3 (for t> tc) where Z* and β are the effective charge and velocity relative to c, the velocity of light, of the incident ion, respectively, D the dose in unit of Gy, t the radial distance in unit of nm, tc the critical distance empirically determined. Then, if we know the yield of any chemical reaction as a function of dose from the results of experiments using γ-radiations or fast electrons or theoretical calculations, we can calculate the probability for the yield of the chemical reaction in the system bombarded with a heavy ion of the effective charge Z* and velocity β. The results of the present calculation of the LET-values and of G(Fe3+) in the ferrous sulfate acidic solution are presented and compared with reported experimental results. 相似文献
13.
Reaction of trans-[Pt(H) 2(PCy 3) 2], 1, with [60]fullerene at room temperature affords [Pt(PCy 3) 2( η2-C 60)], 2, in nearly quantitative yield. The most probable reaction pattern is the insertion of a fullerene 6,6 junction onto a Pt-H bond yielding an η1 alkyl derivative which, after hydrogen extrusion, gives 2. On the other hand, addition of 1 to different electron-deficient olefins, such as dimethyl maleate and fumarate, furnishes mixtures of both η1 metal—alkyl and η2 metal—olefin derivatives. If tetrachloroethylene is used as 2 π component, trans-[PtCl(H)(PCy 3) 2] forms exclusively. 相似文献
14.
Hyperquenching of liquid water with cooling rates of 10 6–10 7 K s −1 yields glassy water. Upon γ-irradiation at 77 K, the only paramagnetic species accumulating in hyperquenched glassy water are the hydroxyl and hydroperoxyl radicals. There are no hydrogen atoms or electrons seen by the ESR technique. For irradiation doses up to about 70 kGy, the relative contributions of hydroxyl and hydroperoxyl radicals to the total amount of paramagnetic species remain virtually constant. The total amount of paramagnetic species, n, is sublinear in dose, d, well approximated by n=8.55×10 16d0.8 for n in spin g −1 and d in kGy. 相似文献
15.
For a closed-shell MO configuration with 2 n electrons which occupy n non-degenerate canonical MOs, it is deduced that the RHF energy, Σ ni=1[2 H0n+Σ nj-1(2 Jij-K ij)], may be expressed in Hückel-like form as 2Σ ni-1ε, −Σ ni-1[ ji(λ+1)+1,(λ+2)] with λ=2( n- i). The l i(λ+1) and Ii(λ+2) are the ionization potentials for the HOMO ψ, which arises after λ and λ+1 electrons have been successively removed from the initial configuration. 相似文献
16.
An η1-butadienyl complex [ trans-η1-CH 2=C(Me)C=CH 2Pd(PPh 3) 2Cl] (1) reacted with [( μ- η2: η2-1,3-butadiene)Pd 2(PPh 3)( μCl)Cl] (2) to result in displacement of the diene ligand of 2 accompanied by exchange of PPh 3 of 1 with Cl anion of 2 producing a butadienyl tripalladium cluster [( μ-CH 2=C(Me)C=CH 2)Pd(PPh 3)Cl 2 · Pd 2(PPh 3) 2( μ-Cl)] (3) stabilized by the zwitterionic structure in moderate yield. The X-ray structure analysis of 3 revealed rigid binding of [Pd 2(PPh 3) 2( μ-Cl)] + and [CH 2 =C(Me)C=CH 2Pd(PPh 3)Cl 2] − through the π-bond coordination of the butadienyl group to the dipalladium cation. 相似文献
17.
CaRg n+ (Rg=He, Ne, Ar) complexes with n=1–4, are investigated by performing using the B3LYP/6-311+G (3df) density functional theory calculations. The CaHe n+ ( n=1–4) complexes are found to be stable. In the case of CaNe n+ and CaAr n+, stable structures and stationary point were found only for n=1 and 2. For n=3 in the C3V and the D3h point group as well as for n=4 in the Td (tetrahedral) point group a saddle point (imaginary frequency) is observed and global minimum could be obtained along the potential energy surface. 相似文献
18.
Triphenyltelluronium hexachloroplatinate (1), hexachloroiridate (2), tetrachloroaurate (3), and tetrachloroplatinate (4) were prepared from Ph 3TeCl and potassium salts of the corresponding anions. Upon recrystallization of 4 from concentrated nitric acid, K 2[PtCl 6] and (Ph 3Te)(NO 3)·HNO 3 (5) were obtained. The crystal structures of 1–3 and 5 are reported. Compounds 1 and 2 are isostructural. They are triclinic, P
, Z=2 (the asymmetric unit contains two formula units). Compound 1: a=10.7535(2), b=17.2060(1), c=21.4700(3) Å, =78.9731(7), β=77.8650(4), γ=78.8369(4)°. Compound 2: a=10.7484(2), b=17.1955(2), c=21.4744(2) Å, =78.834(1), β=77.649(1), γ=78.781(1)°. Compound 3 is monoclinic, P2 1/ c, Z=4, a=8.432(2), b=14.037(3), c=17.306(3) Å, β=93.70(3)°. Compound 5 is monoclinic. P2 1/ n, Z=4, a=9.572(2), b=14.050(3), c=13.556(3) Å, β=90.76(3)°. The primary bonding in the Ph 3Te + cation in each salt is a trigonal AX 3E pyramid with Te---C bond lengths in the range 2.095(8)–2.14(2) Å and the bond angles 94.1(6)–100.9(5)°. The weak TeCl (1–3) and TeO (5) secondary interactions expand the coordination sphere. In 1 and 2 the cation shows a trigonal bipyramidal AX 3YE coordination with one primary Te---C bond and the shortest secondary TeCl contact in axial positions and the two other Te---C bonds and the lone-pair in equatorial positions. The cation in 3 shows a distorted octahedral AX 3Y 3E environment and that in 5 is a more complex AX 3Y 3Y′ 2 arrangement. In both latter salts the structure is a complicated three-dimensional network of cations and anions. 相似文献
19.
Two nickel (imidazole) complexes, Ni(im) 6Cl 2·4H 2O (1) and Ni(im) 6(NO 3) 2 (2) (im=imidazole) have been synthesized and characterized by elemental analysis, IR, UV, TG and single crystal X-ray diffraction. 1 crystallizes in the triclinic space group P-1 with a=8.800(6) Å, b=9.081(6) Å, c=10.565(7) Å, =75.058(9)°, β=83.143(8)°, γ=61.722(8)°, V=718.3(8) Å 3, Z=1 and R1 ( wR2)=0.0469 (0.1497). 2 crystallizes in the trigonal space group R-3 with a=12.370(6) Å, b=12.370(6) Å, c=14.782(14) Å, =90.00°, β=90.00°, γ=120.00°, V=1959(2) Å 3, Z=3 and R1 ( wR2)=0.0358 (0.0955). 1 and 2 exhibit different supramolecular network due to their different counter anions and different hydrogen bonding connection. In compound 1, [Ni(im) 6] 2+ cation and counter anions Cl − alternatively array in an ABAB fashion via N–HCl hydrogen bonding. In compound 2, the plane of each NO 32− is almost parallel and each NO 32− connect three different [Ni(im) 6] 2+ cations via N–HO hydrogen bonding. 相似文献
20.
Fulvic acids (FAs) were extracted by alkali extraction from different soil samples in China, then purified using resins and characterized by Fourier transform infrared spectroscopy. The complexing ability of FAs was investigated by measuring the stability constants of rare earth elements (REEs) (La 3+, Ce 3+, Sm 3+, Gd 3+, Y 3+) with FAs by the ion exchange technique. The results indicated that maximum binding ability forY 3+ (4.414.44) was higher than other REEs (La 3+, Ce 3+, Sm 3+, Gd 3+) (0.721.03). There were two types of binding sites in the functional groups of fulvic acids. The complexing reaction followed two steps. The stability constants ( K1 and K2) of REEs with FAs were calculated from experimental data by division of Scatchard plots into two straight-line segments. Y 3+ (log K1=5.72±0.05, log K2=4.83±0.01) also has higher stability constants than the other four REEs (log K1=4.37±0.16, log K2=3.62±0.28). 相似文献
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