Authors: Yao Wu, Ji Yong Chen, Yu Mei Xiao, Bang Cheng Yang, Xing Dong Zhang
Abstract: It is very necessary to develop a real biomimetic compound coating of CaP with
organic component and investigate quantitatively the effects of different bovine serum albumin (BSA) concentration on the crystallite properties of the coprecipitated CaP layer. Bioactivated Ti was immersed in Ca-P solution with different BSA contents to obtain different biomimetic coating. The coatings were analyzed with scanning electron microscopy (SEM) and X-ray diffraction (XRD). With the increase of BSA, the crystals on the coating grew more slowly but packed more closely. The preferential crystallographic direction of 002 of hydroxyapatite became less distinguishable and the crystallinity of the deposited hydroxyapatite decreased gradually. The crystallite sizes reduced with the addition of BSA proteins. Accordingly, when a certain content of BSA protein was added to
the Ca-P solution, Ti surface would form a real biomimetic coating with the crystal size and crystallinity similar to the natural bone.
363
Authors: Masahiko Inagaki, Yoshiyuki Yokogawa, Tetsuya Kameyama
Abstract: Highly oriented hydroxyapatite (HA) coatings were prepared on titanium (Ti) substrates through a radio-frequency thermal plasma spraying method. XRD patterns showed that the HA coating layer had an structure with (00l) preferred crystal orientation. TEM observation showed that 200-800 nm-width prismatic crystals were formed in HA splats and the longitudinal axis of such
prismatic crystals oriented vertical to the coating's surface. TEM images also indicate that the interface between prismatic crystals became compacted. SAD pattern show that the longitudinal axis of prismatic crystals corresponds to the <001> axis of HA.
615
Authors: Huan Yong Li, Wan Qi Jie, Xiao Qin Wang, Ke Wei Xu
Abstract: The microstructure and surface micromorphology of ZnSe single crystals grown directly from
zinc and selenium have been investigated using rotation orientation x-ray diffraction (RO-XRD), atomic
force microscope (AFM) and field emission scanning electron microscope (FE-SEM). The ZnSe samples
exhibit only the surface leaning to (111) singular face by the angle of 3.13°, which is the buildup of
two-dimensional dendritic crystal layers. Numerous nuclei and cavities distribute unevenly across the
crystal surface, governing the formation of growth layer, while the dendritic crystal layers develop rapidly
by margining the smaller nuclei. The formation of these microstructure and micromorphology on the
surface of ZnSe crystals depends on the surface supersaturation and the growth parameters.
633
Authors: Wei Li, Liu Zhu Chen, Peng Sha Pang
Abstract: Owing to the excellent biocompatibility and corrosion-resistance of titanium and
bioactivity of hydroxyapatite, the titanium/hydroxyapatite composite material combining their
advantages is a highlight with bright prospects in medical clinics. In the present paper, the microarc
oxidation (MAO) was performed on commercial pure titanium at first. Furthermore, the
hydrothermal treatment (HT)was given with media of deionized water at 200°C for 4h in an
autoclave. The surface morphology of the samples was observed by scanning electron microscopy
(SEM), and the detailed composition was analyzed with Energy-Dispersive X-Ray Spectroscopy
(EDS). The X-ray diffraction analysis (XRD) was employed to characterize the crystal structure of
composite. The results indicate that the titania film contains the Ca and P elements on titanium
substrate after MAO, which converts into the hydroxyapatite crystals via hydrothermal treatment.
The smaller size and amount of hydroxyapatite crystals are found when lower voltage is presented.
But there are converse phenomena with higher voltage, especially, the differences can be neglected
above 400V. It is shown that the micro-hole and hollow surface of titania film can induce the
hydroxyapatite nucleation and growth as two different forming ways. The hydroxyapatite has a
preference of forming in hollow surface with lower voltage, however, the presences of the micro-hole
and hollow surface of titania film are occurring for higher voltage. The hydroxyapatite forming in
micro-hole shows needle-like crystal and high bonding strength with surrounding titania film because
of the mechanical restrict force from micro-hole wall. Also it is noted that hydroxyapatite crystals
incline to precipitate on the film surface with high Ca and P concentrations after the hydrothermal
treatment.
734
Authors: Emil Tymicki, Krzysztof Grasza, Katarzyna Racka, Marcin Raczkiewicz, Tadeusz Łukasiewicz, Maciej Gała, Kinga Kościewicz, Ryszard Diduszko, Rafał Bożek
Abstract: 4H-SiC single crystals grown by the seeded physical vapour transport method have been investigated. These crystals were grown on 6H-SiC seeds. The influence of the seed temperature, form and granulation of SiC source materials on the stability and efficiency of the 4H polytype growth have been investigated. A new way of the seed mounting - with an open backside - has been used. Crystals obtained were free of structural defects in the form of hexagonal voids. The crystalline structure of SiC crystals was investigated by EBSD (Electron Backscatter Diffraction) and X-Ray diffraction methods. Moreover, defects in crystals and wafers cut from these crystals were examined by optical, scanning electron and atomic force microscopy combined with KOH etching.
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