Self-assembled 3D flowerlike Lu2O3 and Lu2O3 : Ln(3+) (Ln = Eu, Tb, Dy, Pr, Sm, Er, Ho, Tm) microarchitectures: Ethylene glycol-mediated hydrothermal synthesis and luminescent properties

Three-dimensional flowerlike Lu2O3 and Lu2O3:Ln(3+) (Ln = Eu, Th, Dy, Pr, Sm, Er, Ho, Tm) microarchitectures have been successfully synthesized via ethylene glycol (EG)-mediated hydrothermal method followed by a subsequent heat treatment process. X-ray diffraction, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectra, thermogravimetric and differential thermal analysis, elemental analysis, inductively coupled plasma atomic absorption spectrometric analysis, ion chromatogram analysis, X-ray photoelectron spectra, scanning electron microscopy, transmission electron microscopy, photoluminescence spectra as well kinetic decays, and cathodoluminescence spectra were used to characterize the samples. Hydrothermal temperature, EG, and CH3COONa play critical roles in the formation of the lutetium oxide precursor microflowers. The reaction mechanism and the self-assembly evolution process have been proposed. The as-formed lutetium oxide precursor could transform to Lu2O3 With their original flowerlike morphology and slight shrinkage in the size after postannealing process.

Direct electrochemistry and electrocatalysis of horseradish peroxidase immobilized in sol-gel-derived ceramic-carbon nanotube nanocomposite film

The sol-gel-derived ceramic-carbon nanotube (SGCCN) nanocomposite film fabricated by doping multiwall carbon nanotubes (MWNTs) into a silicate get matrix was used to immobilize protein. The SGCCN film can provide a favorable microenvironment for horseradish peroxidase (HRP) to perform direct electron transfer (DET) at glassy carbon electrode. The HRP immobilized in the SGCCN film shows a pair of well-defined redox waves and retains its bioelectrocatalytic activity to the reduction of O-2 and H2O2, which is superior to that immobilized in silica sol-gel film.

Pr~(3+)或Sm~(3+)掺杂YAG∶Ce的发光特性及其荧光寿命

研究了Pr3+,Sm3+掺杂对YAG∶Ce发射光谱及其荧光寿命的影响。观察到当掺杂Pr3+时,在609nm处出现Pr3+的发射峰,而掺杂Sm3+时,在616nm处呈现Sm3+的发射峰。掺杂Pr3+或Sm3+增加红光区的发射峰将有利于提高YAG∶Ce荧光粉的显色性。实验中测定了(Y0.95Sm0.01Ce0.04)3Al5O12、(Y0.95Pr0.01Ce0.04)3Al5O12、(Y0.96Ce0.04)3Al5O12的荧光寿命(τ),观察到在YAG∶Ce中掺入Pr3+或Sm3+使Ce3+的荧光寿命减小。实验结果表明,少量掺杂Pr3+或Sm3+并未引起基质的结构的变化。

Effect of the addition of YAG(Y3Al5O12) nanopowder on the mechanical properties of lanthanum zirconate

La2Zr2O7 (LZ) is a promising thermal barrier coating material for the high-temperature applications, which could be significantly toughened by the YAG nanopowder incorporated into the matrix. The composites of xYAG/(1-x)LZ (Y=10, 15, 20 vol. %, LZ-x-YAG) were densified by means of high-pressure sintering (HPS) under a pressure of 4.5 GPa at 1650 degrees C for 5 min, by which a high-relative density above 93% could be obtained. The morphologies of the fractured surfaces were investigated by the scanning electron microscope, and the fracture toughness and Vicker's-hardness of the composites were evaluated by the microindentation. The grain size of the LZ matrix drops significantly with the addition of YAG nanoparticles and the fracture type changes from the intergranular to a mixture type of the transgranular and intergranular in the nanocomposites. The LZ-20-YAG nanocomposite has a fracture toughness of 1.93 MPa m(1/2), which is obviously higher than that of the pure LZ (1.57 MPa m(1/2)), and the toughening mechanism is discussed in this paper.

Preparation of CeO2-ZrO2 ceramic fibers by electrospinning

Electrospinning was employed to fabricate polymer-ceramic composite fibers from solutions containing poly(vinyl pyrrolidone) (PVP), Ce(NO3)(3)(.)6H(2)O and ZrOCl2-8H(2)O. Upon firing the composite fibers at 1000 degrees C, Ce(0.67)Zr(0.33)O(2)fibers with diameters ranging from 0.4 to 2 mu m were synthesized. These fibers exhibit strong resistance to sintering. They still have specific surface area around 11.8 m(2)/g after being heated at 1000 degrees C for 6 h.

Preparation of In2O3 ceramic nanofibers by electrospinning and their optical properties

Electrospinning was employed to fabricate polymer-ceramic composite fibers from solutions containing polyvinyl pyrrolidone (PVP) and In(NO3)(3)center dot 4(1)/2H2O. Upon firing the composite fibers at 800 degrees C, In2O3 fibers with diameters ranging from 200 to 400 nm were synthesized. This indium oxide calcined at 800 degrees C is a body-centered cubic cell. The photoluminescence (PL) properties of the as-formed In2O3 nanofibers were investigated. The In2O3 nanofibers show a strong PL emission in the ultraviolet (UV) region under shorter UV light irradiation.

The extraction and separation of Ho, Y, and Er(III) with the mixtures of Cyanex 302 and another organic extractant

The extraction and separation of Ho, Y, and Er(III) with the mixtures of bis(2,4,4-trimetylpentyl)monothiophosphinic acid (Cyanex 302) and another organic extractant, such as acidic organic extractant (di-2-ethylhexyl phosphoric acid P204, 2-ethythexyl phosphoric acid mono-2-ethylhexyl ester P507, di-2-ethylhexyl phosphinic acid P229, and sec-nonylphenoxy acetic acid CA-100), neutral organic extractant (tri-n-butyl phosphate TBP, di-(1-metylheptyl)metyl phosphate P350, and branched trialkylphosphinic oxide Cyanex 925) or primary amine N1923, has been investigated in this paper. The extractability and separation ability for the Ho, Y, and Er with the mixtures of Cyanex 302 and organic extractants has been compared. The synergistic effect of the Ho, Y, and Er extraction with the mixtures of Cyanex 302 and P229, Cyanex 925, CA-100, or N1923 has been explored and the synergistic enhancement coefficients have been calculated. At last, the Y3+ synergistic extraction with the mixtures of Cyanex 302 and CA-100 has been determined and the extracted complex has been deduced.

Ceramic materials for thermal barrier coatings

This paper summarizes the basic properties of ceramic materials for thermal barrier coatings. Ceramics, in contrast to metals, are often more resistant to oxidation, corrosion and wear, as well as being better thermal insulators. Except yttria stabilized zirconia, other materials such as lanthanum zirconate and rare earth oxides are also promising materials for thermal barrier coatings.

Eu~(3+)和Ho~(3+)对乙醇在Pt-TiO_2/C电极上氧化的助催化作用

报道了用循环伏安法研究Eu3+和Ho3+吸附的碳载Pt-TiO2(pt-TiO2/C)催化剂对乙醇电化学氧化的助催化作用.发现无论在中性溶液中还是在酸性溶液中,当Pt-TiO2/C催化剂吸附Eu3+或Ho3+后,都可以使乙醇的电催化氧化电流密度明显增加,其原因主要是Eu3+或Ho3+都能促进吸附的CO的电氧化.

Ho~(3+)对吸附CO电化学氧化的促进作用

研究了吸附在Pt/C催化剂上的Ho3+对吸附CO的电氧化的影响.结果表明,无论在中性和酸性溶液中,在较大的温度范围内,Ho3+对CO在Pt/C催化剂上的电氧化都有促进作用,其原因是吸附Ho3+的存在减弱了CO在Pt/C催化剂上的吸附强度.其次,在中性溶液中,Ho3+对吸附CO的电氧化的促进作用比在酸性溶液中大.第三,无论在酸性还是中性溶液中,温度的升高有利于发挥Ho3+对吸附CO的电氧化的促进作用.

Application of ceramic carbon materials for solid-phase extraction of organic compounds

Ceramic carbon materials were developed as new sorbents for solid-phase extraction of organic compounds using chlorpromazine as a representative. The macroporosity and heterogeneity of ceramic carbon materials allow extracting a large amount of chlorpromazine over a short time. Thus, the highly sensitive and selective determination of chlorpromazine in urine sample was achieved by differential pulse voltammograms after only 1-min extraction. The total analysis time was less than 3 min. In comparison with other electrochemical and electrochemi-luminescent methods following 1-min extraction, the proposed method improved sensitivity by about 2 and 1 order of magnitude, respectively. The fast extraction, diversity, and conductivity of ceramic carbon materials make them promising sorbents for various solid-phase extractions, such as solid-phase microextraction, thin-film microextraction, and electrochemically controlled solidphase extraction. The preliminary applications of ceramic carbon materials in chromatography were also studied.

Electrochemiluminescent detection based on solid-phase extraction at tris(2,2 '-bipyridyl)ruthenium(II)-modified ceramic carbon electrode

A sensitive electrochemiluminescent detection scheme by solid-phase extraction at Ru(bpy)(3)(2+)-modified ceramic carbon electrodes (CCEs) was developed. The as-prepared Ru(bpy)(3)(2+)-modified CCEs show much better long-term stability than other Nafion-based Ru(bpy)(3)(2+)-modified electrodes and enjoy the inherent advantages of CCEs. The log-log calibration plot for dioxopromethazine is linear from 1.0 x 10(-9) to 1.0 x 10(-4) mol L-1 using the new detection scheme. The detection limit is 6.6 x 10(-10) mol L-1 at a signal-to-noise ratio of 3. The new scheme improves the sensitivity by similar to 3 orders of magnitude, which is the most sensitive Ru(bpy)(3)(2+) ECL method. The scheme allows the detection of dioxopromethazine in a urine sample within 3 min. Since Ru(bpy)(3)(2+) ECL is a powerful technique for determination of numerous amine-containing substances, the new detection scheme holds great promise in measurement of free concentrations, investigation of protein-drug interactions and DNA-drug interactions, pharmaceutical analysis, and so on.

Glassy carbon ceramic composite electrodes

A new carbon composite electrode material, based on dispersing glassy carbon (GC) microparticles into methyltrimethoxysilane-derived sol, is described in the present paper. The resulting glassy carbon ceramic composite electrodes (GCCEs) combine the electrochemical properties of GC with the advantages of composite electrodes, and thus offer high electrochemical reactivity, low background current and are easy to prepare, modify and renew. The new material has a low double-layer capacitance and a wide potential window. Scanning electron microscopy (SEM) images indicate significant difference in the structure of GCCE and carbon ceramic composite electrode (CCE). The electrochemical properties and advantages of GCCE should find broad utility in electroanalysis.