Miao Chen

Preparation and characterization of ZrO2 thin film on sulfonated self-assembled monolayer of 3-mercaptopropyl trimethoxysilane

Abstract Silane coupling reagent (3-mercaptopropyl trimethoxysilane (MPTS)) was prepared on single-crystal Si substrate to form two-dimensional self-assembled monolayer (SAM) and the terminal ue5f8SH group in the film was in situ oxidized to ue5f8SO3H group to endow the film with good chemisorption ability. Thus, ZrO2 thin film were deposited on the oxidized MPTS-SAM, by enhanced hydrolysis of zirconium sulfate (Zr(SO4)2·4H2O) solution in the presence of HCl at 70xa0°C, making use of the chemisorption ability of the ue5f8SO3H group. The thickness of the films was determined with an ellipsometer, while the chemical feature, phase composition, thermal stability, and morphology of the films were analyzed by means of Fourier transformation infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction analysis, thermogravimetric analysis, and atomic force microscopy. As the results, the as-deposited ZrO2 film was composed of nanocrystalline tetragonal ZrO2 (t-ZrO2) and an amorphous basic zirconium sulfate. The annealing of the films at 500xa0°C led to crystallization to t-ZrO2, while further heating to 800xa0°C eliminated S in the film, and the ZrO2 film consisted of nanocrystalline tetragonal ZrO2 and monoclinic ZrO2 in this case. The as-deposited ZrO2 thin films were compact and crack-free, showing quadratically-looking features which were not observed previously, while the thickness of the ZrO2 films decreased with increasing annealing temperature. Since the ZrO2 film was well adhered to the MPTS-SAM, it might find promising application in the surface-modification of single-crystal Si and SiC in microelectromechanical systems (MEMS).

Determination of trace europium based on new fluorimetric system of europium(III) with thenoyltrifluoroacetone and N, N'-dinaphthyl-N, N'-diphenyl-3,6-dioxaoctanediamide

In the present paper, N,N-dinaphthyl-N,N-diphenyl-3,6-dioxaoctanediamide acts as a specific reagent for enhancing the fluorescence intensity of Eu(III) complex with thenoyl trifluoroacetone (TTA), the spectrofluorimetric determination of trace amounts of Eu(III) based on the above system was carried out and its luminescence mechanism was studied. The excitation and emission wavelengths are 343.6 and 613.3 nm, respectively. The fluorescence intensities vary linearly with the concentration of europium(III) in the range 3.647x10(-3)-3.039 mug ml(-1) for the original fluorescence with a detection limit down to 2.279x10(-4) mug ml(-1) and the standard deviation is 0.063 mug ml(-1) for 10 times measurements, and in the range 7.598x10(-4)-0.0243 mug ml(-1) (SD=0.035 for 15 times measurements), 0.06078-0.6100 mug ml(-1) (SD=0.52 for 10 times measurements) for the first derivative fluorescence signal with a detection limit down to 8.566x10(-5) mug ml(-1). The interferences of other rare earths and some of inorganic ions are described. This method is a direct, rapid, selective and sensitive analytical method for the determination of trivalent europium in rare earth ore samples and high purity of rare earth oxides.

Determination of trace europium based on new ternary fluorimetric enhancement system of europium(III) with thenoyltrifluoroacetone and trisalicylicamido triethylamine

In this work, a newly synthesized ligand, trisalicylicamido triethylamine, acts as a specific reagent for enhancing the fluorescence intensity of EuIII complex with thenoyltrifluoroacetone. The spectrofluorimetric determination of trace amounts of EuIII based on the above system was carried out and its luminescence mechanism was studied. The excitation and emission wavelengths are 348.9 nm and 613.4 nm, respectively. The fluorescence intensities vary linearly with the concentration of EuIII in the range 7.598 × 10–7 g l–1–3.799 × 10–4 g l–1 with a detection limit of 1.520 × 10–8 g l–1 and a standard deviation of 1.80 × 10–6 g l–1 for 10 measurements. The interferences of some rare-earth metals and inorganic ions are described. This method is a direct, rapid, selective and sensitive analytical procedure for the determination of trivalent europium in high purity yttrium oxide.

A simple and 'green' synthesis of polymer-based silver colloids and their antibacterial properties.

Stable silver colloids were prepared using polyethylene glycol (PEG) as an environment friendly reduction agent and stabilizer, and with H2O as solvent. The Ag colloids were characterized by UV/VIS spectroscopy, transmission electron microscopy (TEM), and atom force microscopy (AFM). TEM and AFM of the sample showed uniform and monodispersive particle distribution in the colloids. The particle size is found to be less than 10 nm. The antibacterial activity of the Ag colloids was also studied. The results showed that the sample had high antibacterial activity toward Gram-positive and Gram-negative bacteria, and fungi.

Preparation of ZnO Film on 2024Al Surface for Hydrophobicity Investigation

A uniform ZnO film with microscale rod-like structure has been obtained on 2024Al surface by the hydrothermal method and perfluorooctanoicacid has been used to enhance the surface hydrophobic performance of the ZnO film. The as-prepared ZnO film was characterized by scan electron microscope (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectrum (XPS). The results indicate that the ZnO film is uniform and the ZnO microrods are 2 um in length. The water contact angle of hydrophobic surface is 146° and the sliding angle is 10°.

Preparation of SnO2 Nanocrystals by Microwave Irradiation and Their Catalytic Activity

Microwave irradiation technique was applied to the preparation of SnO2 nanocrystals by hydrolyzing tin(IV) chloride. The crystallization time was shortened drastically to 11 min from several hours for typical hydrothermal synthesis. The synthesized products were characterized by XRD, TEM, and TG‐DTA. The size of crystals changed from 3 to 24 nm when power and time of microwave irradiation, as well as the difference in calcination temperatures were varied, indicating a possibility for controlling the crystal size. The use of polyvinyl alcohol (PVA) as a protective agent effectively prevented the synthesized particles from agglomeration and favored formation of spherical particles. The catalytic activity of the SnO2 nanocrystals for the esterification of acetic acid with ethanol was also studied.

Preparation and Tribological Behavior of Perfluoropolyether Lubricant Film on ZrO2 Thin Film

Nano-Zr02thin film on Si (111) substrate was prepared via sol-gel method followed by sintering at 550°C. then polar perfluoropolyether lubricant film was fabricated on Zr02 thin film by dip-coating technique. Contact angle measurement and X-ray photoelectron spectrometric analysis showed that Zr02 thin film and Zdol-4000 lubricant film were successfully prepared. The friction behavior of the films against GCrl5 steel and Si3N4 ball were investigated with a one-way reciprocating friction tester. Results showed that Zr02 thin film and Zdol-4000 lubricant film sliding against GCrl5 steel and Si3N4 ball displayed excellent antiwear and friction-reduction performance under the low load (0.5 N) and low sliding speed (90 mm-min).

F-F TRANSITIONAL SPECTRAL ANALYSIS OF YB(DPA)33-COMPLEX

Absorption spectra of Yb(DPA)3 3-complex (where DPA=dipicolinate) in aqueous solution are studied and all of their spectral peaks are assigned based on Double Sphere Coordination Point Charge Field...

STM STUDY OF A SELF-ASSEMBLY BEHAVIOR OF PHTHALOCYANINE AND 1-BROMOHEXADECANE ON HIGHLY ORIENTED PYROLYTIC GRAPHITE

In this paper, we present the results of using alkane derivatives to assist in the adsorption of planar molecules by employing 1-bromohexadecane(C16Br) and phthalocyanine (Pc) as examples. Their assembly behaviors have been well resolved on the observed STM images. The observations presented in this work demonstrate that single molecular arrays of Pc can be obtained with a template of C16Br on highly oriented pyrolytic graphite (HOPG) substrate surface to allow high-resolution STM studies. Binary mixtures of different molar ratios were also observed. By adjusting the molar ratio of Pc to C16Br to about 1:3–1:4, uniform assembly can become dominative on the surface. The resulting high stability and the well ordered assembly are attributed to the increased adsorption barrier of alkanes. This approach could be adapted to the studies of other molecules to observe molecular features and could be helpful in obtaining two-dimensional assemblies of monodispersed molecules, especially planar molecules.

Studies on polarographic adsorptive wave of the system of the rare earth(III)-copper(II)- m-trifluomethyl chlorophosphonazo

Abstract A new heteronuclear complex, rare earth (III)-copper (II)-m-trifluomethyl chlorophosphonazo (CPA-mCF3) system for determining trace rare earth ions is presented. In a medium of 0.02mol/L NH4Cl,1. 0×10−3mol/L Cu(II),1.0×10−5 mol/L CPA-mCF3, a very sensitive polarographic adsorptive wave is observed by using a single sweep oscillopolarograph at about –0.83V (vs. Ag/AgCl). The linear relationship between the peak current and the concentration of rare earth exists from 6. 0×10−9 to 1. 0×10−6 mol/L. The detection limit of rare earth is down to 2. 0×10−9 mol/L for Tm3+. This method has been applied to determine trace RE in several samples of Chinese tea. The results are satisfactory. The composition of the complex is detected as RE (II): Cu (II): CPA-mCF3 = 1: 1: 2.