Bo-An Kang

Sol–gel derived hydroxyapatite films on alumina substrates

Abstract The crystallinity and structural changes of hydroxyapatite films prepared on alumina substrates using a sol–gel process were analyzed by X-ray diffraction (XRD) θ−2θ scans and Fourier transform infrared (FTIR) spectroscopy. Hydroxyapatite films, confirmed by XRD θ−2θ scanning, were obtained by heat treatment at 500 and 700°C from the pre-fired films. A film heat treated at 700°C showed the strongest peak intensities. For a film heat-treated at 500°C, the FTIR and XRD results indicated that carbonate was substituted into the hydroxyapatite lattice.

Waste fluorescent glass and shell derived glass-ceramics

We prepared glass-ceramics by using fluorescent glass and waste shell as starting materials to recycle waste fluorescent glass containing harmful Hg to human body and waste shell, and to resolve environmental problems. Pressed specimens after quenching and grinding were heat treated at 800°C, 900°C and 1000°C for 1 h, respectively. β-wollastonite, gehlenite and sodium calcium silicate were observed by X-ray diffraction studies. Surface morphology and chemical composition were evaluated by field emission-scanning electron microscopy and energy dispersive X-ray spectrometer.

Preparation of epitaxial and polycrystalline bismuth titanate thin films on single crystal (100) MgO by chemical solution deposition

Abstract Epitaxial and polycrystalline Bi 4 Ti 3 O 12 thin films were prepared on single crystal (100) MgO substrates by a chemical solution deposition process using metal naphthenates as starting materials. Pyrolyzed films (at 500°C) were annealed for 30 min in air at 650, 700, 750 and 800°C, respectively. The effects of annealing temperature on the crystallinity, epitaxy and surface morphology of the films were investigated by X-ray diffraction θ-2θ scans, pole-figure analysis, and atomic force microscopy (AFM). Epitaxially grown films annealed at 700 and 750°C, respectively, showed growth of three-dimensional needle-shaped grains. During annealing at 800°C, grain growth of Bi 4 Ti 3 O 12 may be suppressed by the formation of a titanium-rich phase such as Bi 2 Ti 2 O 7 owing to Bi volatilization, resulting in lower root mean square roughness than that of film annealed at 750°C.

Glass-ceramics prepared by waste fluorescent glass

To prepare glass-ceramics reinforced by β-wollastonite, fluorescent glass and calcium carbonate were used as starting materials. β-Wollastonite, gehlenite and sodium calcium silicate were observed by X-ray diffraction analysis, and surface morphology and chemical composition were evaluated by field emission-scanning electron microscopy and energy dispersive X-ray spectrometer.

Nanocrystalline TiO2 thin films on soda-lime-silica glass by using a titanium naphthenate precursor

Abstract TiO 2 thin films were prepared on soda-lime–silica slide glasses by spin coating-pyrolysis process using titanium naphthenate as a starting material. Precursor films were prefired at 500 °C for 10 min in air and finally annealed at 500, 550 and 600 °C for 30 min in air, followed by rapid cooling. Crystallinity of the TiO 2 films was investigated by X-ray diffraction (XRD) analysis. A field emission-scanning electron microscope and an atomic force microscope were adopted for characterizing the surface morphology and the surface roughness of the TiO 2 films. After final annealing at 550 and 600 °C, the XRD patterns consist of only anatase peak of TiO 2 film. Films annealed at 500 and 550 °C exhibited flat surfaces. On the contrary, with the increase in annealing temperature to 600 °C, the TiO 2 film showed growth of three-dimensional needle-shaped grains. For all samples, high transmittance at visible range was obtained by ultra violet–visible–near infrared spectrophotometer.

Preparation of Yttria-Stabilized Tetragonal Zirconia Ceramics for Optical Ferrule

Yttria-stabilized zirconia ceramics are considered to be one of the most important ceramic materials for use in structural applications, because of the high strength and toughness of yttria-stabilized tetragonal zirconia polycrystals. In this work, in order to prepare dense and compact yttria-stabilized tetragonal zirconia body after sintering at 1400°C, we used various raw materials with different particle properties, such as crystallinity, particle size distribution, and particle shape. Crystallinity and tetragonal percentage of the sintered samples were analyzed by X-ray diffraction. Microstructure of the sintered samples was evaluated by field emission-scanning electron microscopy.

Epitaxially Grown LaSrCoO3 Thin Films on Various Substrates by the Sol-Gel Method

LaSrCoO3 thin films have been prepared on various substrates by the sol-gel method using inorganic salts as starting materials. The crystallinity and in-plane alignment of the films were analyzed by X-ray diffraction θ-2θ scans and β scans (pole-figure analysis), respectively. Highly (h00)/(00l)-oriented LaSrCoO3 films with crack-free surfaces were obtained by annealing at 800°C on SrTiO3(100), while films grown on MgO(100) and Si(100) exhibited poor crystallinity. According to the X-ray diffraction θ-2θ scan, crystallinity of the product films was found to depend on lattice-misfit values between the films and the substrates used. On the contrary, the lattice-misfit values were less effective to the epitaxy of the LSCO film. Epitaxial film grown on SrTiO3 annealed at 800°C was found by reciprocal-space mapping (ω-2θ scan) analysis to consist of the pseudocubic phase.

Effect of annealing titanium on in vitro bioactivity

In order to modify titanium surfaces for various biological applications, bioactive and pure titanium oxide thin films were coated on the titanium by thermal oxidation technique. The commercially pure titanium discs after polishing were heated at 500, 550, 600, 650 and 700 °C, respectively, for 10 min in air or in argon. To evaluate the ability of calcium phosphate formation, samples after annealing were soaked in the Eagles minimum essential medium solution. Surface morphology and chemical composition of the samples before or after immersion were characterized by field emission – scanning electron microscopy and energy dispersive X-ray spectrometry.

Growth mechanism of chemical solution derived PZT films on MgO(100) substrate

PZT (Zr : Ti = 0.53 : 0.47) thin films were fabricated by chemical solution deposition with metal naphthenates used as starting materials. Effect of final annealing temperature on epitaxy and surface morphology of the films were investigated. PZT films prefired at 200°C were crystallized to be highly (00l)/(h00)-oriented at final annealing temperatures of 750°–800°C. The film annealed at 750°C was smooth and no distinct texture was exhibited, while the rosette-type microstructure caused by lead volatilization was observed in the films after annealing at 800°C.

Crystallinity and surface morphology of chemical solution derived epitaxial Bi4Ti3O12 thin films on (100)LaAlO3

Bi4Ti3O12 thin films were prepared on single-crystal (100)LaAlO3 substrates by chemical solution deposition using metal naphthenates as starting materials. Precursor films were pyrolyzed at 500°C for 10 min in air and finally annealed at 650, 700, 750 and 800°C for 30 min in air, followed by rapid cooling. Crystallinity and in-plane alignment of the thin films were investigated by X-ray diffraction θ–2θ scans and pole-figure analysis. A field emission-scanning electron microscope and an atomic force microscope were adopted for characterizing the surface morphology and the surface roughness of the films. Epitaxially grown thin films annealed at 650 and 700°C exhibited extremely flat surfaces. On the contrary, with the increase in annealing temperatures to 750 and 800°C, the columnar grain size and width of the films uniformly increased.