Yanhua Fan

The effects of detected gases on spectroscopic properties of phthalocyanine Langmuir-Blodgett films

Abstract Tetrakis-4-(2,4-di-amylphenoxy) phthalocyaninato-polysiloxane (R 4 PcPS) was derived from the correspondingly substituted phthalocyaninatosilicon hydroxide (R 4 PcSi (OH) 2 ). The photoluminescence and excitation spectra of R 4 PcPS and P 4 PcSi (OH) 2 solutions in chloroform were shown. The absorption spectra of R 4 PcPS Langmuir-Blodgett films, before and after adsorbing I 2 , were compared. The infrared absorption spectra of an asymmetrically substituted copper [tri-4-(2,4-di-amylenoxy)-mono-4-(2-methoxyethoxy)] phthalocyanine (AsyCuPc) Langmuir-Blodgett films, before and after adsorbing NH 3 , were studied.

Synthesis and Properties of Barium Strontium Titanate Thin Films on Copper Foils

Ba0.7Sr0.3TiO3 thin films with a thickness of 300~900 nm were prepared with sol-gel method directly on the copper foils. The films have been processed in almost inert atmosphere such that the oxidation of Cu foil was avoided while allowing the film to crystallize. The crystal structure, morphology and dielectric properties of the films were measured and analyzed. The effects of annealing temperatures and film thickness on the electrical properties were discussed.

Microstructure and properties of barium strontium titanate thin films prepared on copper foils via addition of PEG to the sol precursor

Ba0.7Sr0.3TiO3 thin films have been deposited on copper foils via sol-gel method. The films have been processed in almost inert atmosphere so that the substrate oxidation is avoided while allowing the perovskite phase to crystallize. Polyethylene glycol (PEG) with the molecular weight of 200 was employed to modify the BST precursor solutions. The effect of PEG on the microstructure and dielectric properties of BST thin films has been investigated. Leakage current for BST thin film made from the sol with PEG modification is reported.

Preparation and Properties of CNTs-Ti3Al/B4C Composites

CNTs-TiAl/B4C composite has been obtained by high energy ball milling and hot press sintering. These technical process promoted the solid reaction and resulted in the formation of composites comprising Ti-Al, TiC, TiB2 and B4C. The SEM images and measurement of the mechanical properties proved that the addition of 1.5wt.% CNTs further improves the fracture toughness and the bending strength of TiAl/B4C composites.

Microstructure and IR Studies of Ag Ions-Zeolite

Ag-zeolite crystal have been obtained through immersing Na86–X (Na86[(AlO2)86(SiO2)106]46 .2H2O) zeolite in 0.1 M AgNO3 solution for 12 h. Information on the interaction of Ag+ cations with framework oxygens was obtained by analyzing of IR spectra. SEM and EDS reveal that the microstructure of zeolite is tetrahedral with some little cluster between tetrahedral crystal and Ag element exists in the crystal.

A DFT Study on the Geometric Structure and Magnetic Properties of (FeAl)n (n≤4) Clusters

Theoretical study on the geometric structures and magnetic properties of small (FeAl)n (n=1-4) clusters has been carried out at the BPW91 level. In all the (FeAl)n clusters, the iron atoms are brought together, yielding a maximum of Fe-Fe bonds, and the aluminum atoms are located around a Fe core with a maximum of Fe-Al bonds which is different the bulk ordered FeAl alloy dominated by the Fe-Al bonds. As opposed to the bulk FeAl with non-magnetic, the small nano-clusters are highly magnetic moment dominated by Fe-Fe clustering.

The Effect of Annealing Atmosphere on Electrical Properties of BST Thin Films Prepared on Copper Foils

Ba0.7Sr0.3TiO3 (BST) thin films have been prepared on copper foils via sol-gel method in almost inert atmosphere containing different level of oxygen which was achieved by flowing high purified argon with the varied rate from 0.3 L/min to 2.0 L/min. X-ray diffraction pattern of the BST thin film exhibits dominant perovskite phase. SEM images reveal good crystallization and much dense structure of the thin film. The BST thin film annealed at almost inert atmosphere by flowing the high purified argon at the rate of 0.5 L/min, exhibits highest dielectric constants which are 1549.65 and 1350.86 at the frequency of 10 kHz and 1 MHz, respectively. Additionally, the film also shows optimized ferroelectric behavior and low leakage current density. The mechanism of the annealing atmosphere on properties of BST thin films was investigated.