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1.
A novel organic gel film modified electrode was simply and conveniently fabricated by casting LixMoOy and polypropylene carbonate (PPC) onto the surface of a gold electrode. The cyclic voltammetry and amperometry studies demonstrated that the LixMoOy film modified electrode has a high stability and a good electrocatalytic activity for the reduction of iodate. In amperometry, a good linear relationship between the steady current and the concentration of iodate was obtained in the range from 3×10–7 to 1×10–4 mol L–1 with a correlation coefficient of 0.9997 and a detection limit of 1×10–7 mol L–1. 相似文献
2.
Liqiang Luo Yuting Zhang Fang LiXiaojing Si Yaping DingDongmei Deng Tianlin Wang 《Analytica chimica acta》2013
A series of spinel-type CoxNi1−xFe2O4 (x = 0, 0.2, 0.4, 0.5, 0.6, 0.8, 1.0) magnetic nanomaterials were solvothermally synthesized as enzyme mimics for the eletroctrocatalytic oxidation of H2O2. X-ray diffraction and scanning electron microscope were employed to characterize the composition, structure and morphology of the material. The electrochemical properties of spinel-type CoxNi1−xFe2O4 with different (Co/Ni) molar ratio toward H2O2 oxidation were investigated, and the results demonstrated that Co0.5Ni0.5Fe2O4 modified carbon paste electrode (Co0.5Ni0.5Fe2O4/CPE) possessed the best electrocatalytic activity for H2O2 oxidation. Under optimum conditions, the calibration curve for H2O2 determination on Co0.5Ni0.5Fe2O4/CPE was linear in a wide range of 1.0 × 10−8–1.0 × 10−3 M with low detection limit of 3.0 × 10−9 M (S/N = 3). The proposed Co0.5Ni0.5Fe2O4/CPE was also applied to the determination of H2O2 in commercial toothpastes with satisfactory results, indicating that CoxNi1−xFe2O4 is a promising hydrogen peroxidase mimics for the detection of H2O2. 相似文献
3.
Zr1−xLnxW2O8−x/2 solid solutions (Ln=Eu, Er, Yb) of different substitution fractions x have been synthesized. Their X-ray diffraction (XRD) patterns have been indexed and lattice parameters calculated based on the α-ZrW2O8 structure. The coefficients of thermal expansion (CTEs) of these solid solutions were estimated to be −10.3×10−6 K−1 in temperature range of 30-100 °C. The solubility of lanthanide ions in these solid solutions decreases linearly with the increase in the radius of substituted lanthanide ions. Based on the concentration dependence of phase transition temperatures, a novel method for determination of solubility of the lanthanide ions in Zr1−xLnxW2O8−x/2 solid solutions has been developed. This method seems to be more sensitive as compared with that based on XRD technique. 相似文献
4.
This work describes the in situ immobilization of Mn(II) phthalocyanine (MnPc) in a porous SiO2/SnO2 mixed oxide matrix obtained by the sol gel processing method. The chemically modified matrix SiO2/SnO2/MnPc, possessing an estimated amount of 8 × 10−10 mol cm−2 of MnPc on the surface, was used to prepare an electrode to analyze dissolved oxygen in water by an electrochemical technique. The electrode was prepared by mixing the material with ultrapure graphite and evaluated using differential pulse voltammetry. Dissolved O2 was reduced at −0.31 V with a limit of detection (LOD) equal to 7.0 × 10−4 mmol L−1. A mechanism involving four electrons in O2 reduction was determined by the rotating disk electrode technique. 相似文献
5.
The thin films of mixture of xBiFeO3-(1 − x)Bi4Ti3O12 (x = 0.4, 0.5, and 0.6) system were prepared by a sol–gel process. The thicknesses of the thin films were 540, 500, and 570 nm,
respectively. The crystal structure of all thin films annealed at 650 °C was analyzed by X-ray diffraction. It was found that
the thin films at x = 0.4 and 0.5 mainly consisted of a Bi4Ti3O12 phase while Bi5Ti3FeO15 was the major phase of the thin film at x = 0.6. The thin film (x = 0.6) showed better ferroelectric properties in remnant polarization and polarization fatigue than those observed in the
thin films (x = 0.4 and 0.5). The values of remnant polarization 2P
r and coercive field 2E
c of the thin film at x = 0.6 were 36 μC/cm2 and 192 kV/cm at an applied electric field of 260 kV/cm, respectively. There was almost no polarization fatigue up to 1010 switching cycles. Also weak ferromagnetism was observed in the thin film at x = 0.6. 相似文献
6.
7.
Kouta Iwasaki Tsuyoshi Ito Yuji Arita Tsuneo Matsui 《Journal of solid state chemistry》2008,181(11):3145-3150
Thermoelectric properties of polycrystalline La1−xSrxCoO3, where Sr2+ is substituted in La3+ site in perovskite-type LaCoO3, have been investigated. Sr-doping increases the electrical conductivity (σ) of La1−xSrxCoO3, and also decreases the Seebeck coefficient (S) for 0.01?x?0.40. A Hall coefficient measurement reveals that the increase in electrical conductivity arises from increases in both carrier concentration and the Hall mobility. The decrease in the Seebeck coefficient is caused by a decrease in carrier effective mass as well as increase in carrier concentration. The highest power factor (σS2) is 3.7×10−4 W m−1 K−2 at 250 K for x=0.10. The thermal conductivity (κ) is about 2 W m−1 K−1 at 300 K for 0?x?0.04, and increases for x?0.05 because of an increase in heat transport by conductive carrier. The thermoelectric properties of La1−xSrxCoO3 are improved by Sr-doping, and the figure of merit (Z=σS2 κ−1) reaches 1.6×10−4 K−1 for x=0.06 at 300 K (ZT=0.048). For heavily Sr-doped samples, the thermoelectric properties diminish mainly because of the decrease in the Seebeck coefficient and the increase in thermal conductivity. 相似文献
8.
The La(Mn0.5Co0.5)1−xCuxO3−δ series with x=0, 0.05, 0.1, 0.2, 0.4, 0.6, 0.8 and 1 was synthesized by the Pechini method to obtain insight into the phase formation in the quasi-ternary LaMnO3-LaCoO3-“LaCuO3” system caused by the instability of LaCuO3 under ambient conditions. After sintering at 1100°C some remarkable results were obtained: LaMn0.3Co0.3Cu0.4O3−δ crystallized as a single phase in the orthorhombic perovskite structure typical of LaCuO3. Among the synthesized compositions this compound showed the highest electrical conductivity in air at 800°C (155 S cm−1) and also the highest thermal expansion coefficient (α30−800°C=15.4×10−6 K−1). The LaCuO3−δ composition also crystallized as a single phase but in a monoclinic structure although previous investigations have shown that other phases are preferably formed after sintering at 1100°C. The electrical conductivity and thermal expansion coefficient were the lowest within the series of compositions, i.e. 9.4 S cm−1 and 11.9×10−6 K−1, respectively. 相似文献
9.
10.
The photoluminescence properties of xZnO–(100−x)SiO2 (x = 0, 5, 10, 20) containing 1% Eu2O3 prepared by a sol–gel method were systematically investigated. The results indicated that the relative proportion of f–f transitions to charge transfer (CT) absorption decreased with the increase of ZnO concentration. The intensity of 5D0–7FJ transitions of Eu3+ ions was enhanced with the increase of ZnO content due to local structure changes and decreased quantities of Eu3+ ions clusters. The results of fluorescence line narrow (FLN) spectra indicated that Eu3+ ions occupied one site in SiO2 glass and two sites in ZnO–SiO2 glasses. The second-order crystal field parameters were calculated. B20 and B22 for site 1 increased with excitation energy, while ones hardly changed for site 2. 相似文献
11.
In this paper, pseudo-binary (Ag0.365Sb0.558Te)x-(Bi0.5Sb1.5Te3)1−x (x=0-1.0) alloys were prepared using spark plasma sintering technique, and the composition-dependent thermoelectric properties were evaluated. Electrical conductivities range from 7.9×104 to 15.6×104 Ω−1 m−1 at temperatures of 507 and 318 K, respectively, being about 3.0 and 8.5 times those of Bi0.5Sb1.5Te3 alloy at the corresponding temperatures. The optimal dimensionless figure of merit (ZT) of the sample with molar fraction x=0.025 reaches 1.1 at 478 K, whereas that of the ternary Bi0.5Sb1.5Te3 alloy is 0.58 near room temperature. The results also reveal that a direct introduction of Ag0.365Sb0.558Te in the Bi-Sb-Te system is much more effective to the property improvement than naturally precipitated Ag0.365Sb0.558Te in the Ag-doped Ag-Bi-Sb-Te system. 相似文献
12.
The preparation of SiO2-M
x
O
y
(M = V, Sn, Sb) binary oxide thin films by sol-gel method was investigated. The reaction of silicic acid with metal chloride (M = Sn and Sb) or oxychloride (M = V) formed homogeneous solutions. The dip-coating of slide glass and silicon wafer followed by heat treatment gave oxide films having Si—O—M bond. The changes of FT-IR spectra as a function of heat treatment temperature and molar composition confirmed the Si—O—M bonds. The sheet resistance of films increased with an increase on heat treatment temperature and decrease in the content of metal oxide M
x
O
y
. X-ray diffraction peaks were observed for the SiO2-V2O5 films with high V2O5 contents and heat-treated above 250°C, while the others were amorphous. Oxide films heat treated at 500°C had a thickness between 340–470 nm. 相似文献
13.
CrOx/SiO2催化剂上丙烷在CO2气氛中脱氢反应的研究 总被引:2,自引:0,他引:2
采用XRD、UV-vis DRS、ESR和微分吸附量热等技术,考察了铬担载量分别为2.5、5和10wt%的CrOx/SiO2催化剂的结构、表面性质和氧化还原性能。结果表明,催化剂表面上存在多种Cr的氧化态和聚集形式。随着Cr担载量从2.5wt%到10wt%的逐渐增大,催化剂表面占主导地位的Cr物种由CrO3单体转为多聚CrO3和Cr2O3晶相。在CO2气氛中催化剂对丙烷转化率和丙烯选择性的大小顺序为2.5wt%CrOx/SiO2>5wt%CrOx/SiO2>10wt%CrOx/SiO2,反应过程中的原位ESR和UV-visDRS测定结果表明,催化剂表面的反应活性中心为Cr5+,Cr5+可由催化剂预处理过程中Cr3+的氧化及丙烷反应过程中CrO3单体的还原产生,在反应中CO2可使Cr3+重新氧化为Cr5+. 相似文献
14.
Quan-Bao Ma Li-Ping Zhu Yin-Zhu Zhang Bing-Hui Zhao 《Journal of solid state chemistry》2008,181(3):525-529
Highly transparent conductive and near infrared (IR) reflective Gallium-doped ZnMgO (Zn1−xMgxO:Ga) films with Mg content from 0 to 10 at% were deposited on glass substrate by DC reactive magnetron sputtering. X-ray diffraction shows all the ZnMgO:Ga films are polycrystalline and have wurtzite structure with a preferential c-axis orientation. Hall measurements indicate that the resistivity of these films obviously increases with the Mg concentration increasing. The average transmittance of Zn1−xMgxO:Ga films is over 90% in the visible range. All the Zn1−xMgxO:Ga films have low transmittance and high reflectance in the IR region. 相似文献
15.
Petr Ptá?ek František Šoukal Tomáš Opravil Magdaléna Nosková Jaromír Havlica Ji?í Brandštetr 《Journal of solid state chemistry》2011,184(10):2661-2667
The structural changes during thermal conversion of metakaolinite into cubic spinel phase that was in literature considered as Al–Si spinel or γ-Al2O3 were investigated by mid-infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) using medium ordered kaolin with high content of kaolinite. Spectrum features were studied in the mid-infrared region from 4000 to 400 cm−1 as function of fractional conversion that resulted from DSC experiments. The increasing contends of Al–O bonds in the octahedral position (AlO6) was observed during thermal transformation. The high ratio of antisymmetric stretching of Si–O–Al and Si–O–Si bands and bands belonging to stretching of Al–O bonds in the (AlO4) tetrahedra and (AlO6) octahedra decreases exponentially with fractional conversion. The antisymmetric stretching band of Si–O–Si bond in the (SiO4) tetrahedra becomes more expressive due to formation of amorphous SiO2 phase. 相似文献
16.
Nan Zhao Ming-ming Yao Fang Li Fei-peng Lou 《Journal of solid state chemistry》2011,184(10):2770-2775
Ag+ and La3+ surface codoped TiO2 films were successfully prepared by the improved sol–gel and doping processes. The as-prepared specimens were characterized using differential thermal analysis-thermogravimetry (DTA–TG), X-ray diffraction (XRD), high-resolution field emission scanning electron microscopy (FE-SEM), X-ray energy dispersive spectroscopy (EDS), Brunauer–Emmett–Teller (BET) surface area, Photoluminescence spectrum (PL) and UV–vis diffuse reflectance spectroscopy. The photocatalytic activities of the films were evaluated by degradation of an organic dye in aqueous solution. The results of XRD, FE-SEM and BET analyses indicated that the TiO2 films were composed of nano-particles or aggregates with a size of less than 10 nm. With the codoping of Ag+ and La3+, TiO2 films with high photocatalytic activity and clearly responsive to the visible light were obtained. The improvement mechanism by ions doping was also discussed. 相似文献
17.
Anshita Gairola Girish V. Kunte Deepak Chopra T.N. Guru Row A.M. Umarji S.A. Shivashankar 《Polyhedron》2010
A detailed study, involving the synthesis of a single-source precursor containing two metal ions sharing the same crystallographic site, has been undertaken to elucidate the use of such a single-source precursor in a CVD process for growing thin films of oxides comprising these two metals, ensuring a uniform composition and distribution of metal ions. The substituted complexes Cr1−xAlx(acac)3, where acac = acetylacetonate, have been prepared by a co-synthesis method, and characterized using UV–Vis spectroscopy, TGA/DTA measurements, and single crystal X-ray diffraction at low temperature. All the studied compositions crystallize in the monoclinic space group P21/c with Z = 4 in the unit cell. It was observed that the ratio (Al:Cr) of the site occupancy for the metal ions, obtained from single crystal refinement, is in agreement with the results obtained from complexometric titrations. All the solid state structures have the metal in an octahedral environment forming six-membered chelate rings. M–O acac bond lengths and disorder in the terminal carbon have been studied in detail for these substituted metal–organic complexes. One composition among these was chosen to evaluate their suitability as a single-source precursor in a LPMOCVD process (low-pressure metal–organic chemical vapour deposition) for the deposition of a substituted binary metal oxide thin film. The resulting thin films were characterized by X-ray diffraction, scanning electron microscopy, and infrared spectroscopy. 相似文献
18.
Ba(Ti1−x
Sn
x
)O3 (x = 0.10 or 0.15) thin films were deposited on Si(100) and Pt(111)/TiO
x
/SiO2/Si(100) substrates via sol–gel spin-coating. Crack-free thin films could be obtained by single-step deposition, where the
thickness was about 0.46 and 0.29 μm at 1000 and 2000 rpm, respectively. Circular delaminated parts 100 μm in diameter, however,
tended to appear in thicker films deposited at 1000 rpm. On both kinds of substrates, the films were crystallized between
500 and 600 °C, where the perovskite phase emerged as the primary phase, and the formation of single-phase perovskite was
basically achieved between 700–800 °C. The films deposited on Pt(111)/TiO
x
/SiO2/Si(100) substrates, however, tended to have small SnO2 and BaCO3 diffraction peaks, which decreased with increasing spinning rate. The dielectric properties were evaluated on the films deposited
on Pt(111)/TiO
x
/SiO2/Si(100) substrates at 2000 rpm. The films prepared by single-step depositions had dielectric constants of 350 and 230, and
dielectric loss of 0.30 and 0.10 at x = 0.1 and 0.15, respectively. The films prepared by two time deposition had dielectric constants of 450 and 250, and dielectric
loss of 0.21 and 0.19 at x = 0.10 and 0.15, respectively. 相似文献
19.
The isothermal section for the system Ce–Zn–B has been established at 800 °C using electron microprobe analysis and X-ray powder diffraction. No ternary compounds exist and mutual solid solubilities of binary phases are negligible. In the concentration range of 10.0–10.5 at% Ce two structural modifications have been confirmed: high temperature βCe2Zn17 above ∼750 °C with the Th2Zn17 type (R3?m, a=0.90916(4) nm, c=1.3286(1) nm) and low temperature αCeZn7 (Ce1−xZn5+2x; x∼0.33) up to 750 °C for which we attributed the TbCu7 type (P6/mmm, a=0.52424(2), c=0.44274(1) nm). The crystal structure of CeZn7 was derived from the Rietveld refinement of X-ray powder intensities. Precise data on atom site distribution and positional parameters have been furthermore provided from X-ray single crystal refinements for two compounds, for which crystal structures hitherto have only been derived from X-ray diffraction photographs: Ce3Zn11 (Immm, a=0.45242(2) nm, b=0.88942(3) nm, c=1.34754(4) nm) and Ce3Zn22 (I41/amd; a=0.89363(2) nm, c=2.1804(5) nm). 相似文献
20.
Series of compositions Bi2(M′xM1−x)4O9 with x=0.0, 0.1,…, 1.0 and M′/M=Ga/Al, Fe/Al and Fe/Ga were synthesized by dissolving appropriate amounts of corresponding metal nitrate hydrates in glycerine, followed by gelation, calcination and final heating at 800 °C for 24 h. The new compositions with M′/M=Ga/Al form solid-solution series, which are isotypes to the two other series M′/M=Fe/Al and Fe/Ga. The XRD data analysis yielded in all cases a linear dependence of the lattice parameters related on x. Rietveld structure refinements of the XRD patterns of the new compounds, Bi2(GaxAl1−x)4O9 reveal a preferential occupation of Ga in tetrahedral site (4 h). The IR absorption spectra measured between 50 and 4000 cm−1 of all systems show systematic shifts in peak positions related to the degree of substitution. Samples treated in 18O2 atmosphere (16 h at 800 °C, 200 mbar, 95% 18O2) for 18O/16O isotope exchange experiments show a well-separated IR absorption peak related to the M-18Oc-M vibration, where Oc denotes the common oxygen of two tetrahedral type MO4 units. The intensity ratio of M-18Oc/M-16Oc IR absorption peaks and the average crystal sizes were used to estimate the tracer diffusion coefficients of polycrystalline Bi2Al4O9 (D=2×10−22 m2s−1), Bi2Fe4O9 (D=5×10−21 m2s−1), Bi2(Ga/Al)4O9 (D=2×10−21 m2s−1) and Bi2Ga4O9 (D=2×10−20 m2s−1). 相似文献