Abstract: This paper presents a typical coprecipitation method to synthesize silicate-substituted
calcium deficient hydroxyapatite (SiCDHA). A homogeneous aqueous solution of Ca(NO3)2• 4H2O,
H3PO4 and Si(CH3CH2O)4 (TEOS) was used as precursor, and NH3 aqueous solution as precipitator.
A series of samples were prepared by adding the precipitator to the precursor then following a general
coprecipitation route. The results showed that the so-prepared samples were SiCDHA. SiCDHA was
thermal unstable and decomposed to tricalcium phosphate and wollastonite-like phase. These new
phases were helpful to improve the bioactivity of sintered SiCDHA ceramics.
Abstract: Silicate substituted hydroxyapatite bioceramics have been shown to enhance bone repair in
vivo compared to hydroxyapatite (HA), although the amount of silicate ions that can be substituted
alone into the hydroxyapatite structure is limited to approximately 5.2 wt%, or 1.6 wt% Si. This study
describes the substitution of greater levels of silicate ions via co-substitution of silicate ions with
trivalent yttrium ions, without resulting in the formation of any secondary phases. This substitution
mechanism involves a coupled substitution of yttrium and silicate ions for calcium and phosphate
ions, respectively, and enables a level of silicate substitution up to approximately 9 wt%. Two
different substitution mechanisms result in subtle differences in the crystal structure. When the
mechanism xY3+ + xSiO4
4- was used, a small decrease in the a-axis, but no change in the c-axis, of the
unit cell compared to HA was observed. In contrast, when the mechanism x/2Y3+ + xSiO4
4- was used,
a significant increase in the c-axis of the unit cell was observed, compared to HA. XRF analysis and
FTIR spectroscopy supported the proposed substitution mechanisms. These novel substitution
mechanisms not only enable greater levels of silicate-substitution in HA to be prepared, but also allow
the production of compositions with the same level of silicate substitution, and with subtle differences
in chemical structure.
Abstract: Biphasic calcium phosphate (BCP) ceramics, a mixture of hydroxyapatite (HAp) and
beta-tricalcium phosphate (β-TCP), of varying HAp/β-TCP ratios were prepared from fine powders.
Porous BCP ceramic materials with HAp/β-TCP weight rations of 20/80, 40/60, and 80/20 were
prepared. In this study, the bioactivity is reduced at a larger HAp content rate, which is likely
related to the high driving pore for the formation of a new phase, and the reaction rate was
proportional to the β-TCP. The porous BCP ceramics having a bigger porosity rate can easily under
up dissolution. The powder having a larger β-TCP content rate can easily generate a new phase. The
dissolution results confirmed that the biodegradation of calcium phosphate ceramics could be
controlled by simply adjusting the amount of HAp or β-TCP in the ceramics and porosity rate.
Abstract: Biocompatibility of metallic implants and bone in orthopaedic surgery plays an important
role in long-term survivor of the prosthetic implant fixation. However, titanium and its alloys do not
bond to bone in the early stage of implantation (<6 months). On the other hand, titanium alloy
undergoes electrochemical exchange and releases metallic ions in the physiological environment,
which is believed to be the cause of implant failure. Cathodic electrolytic deposition is an important
method in ceramic processing. In this paper, the nanocrystalline BaTiO3 coating were prepared by
electrolytic deposition process. According to the XRD results, we can clearly identified that
electrolytic deposition Barium titanate hydrate gel annealed at 350°C for 1 hr will form to BaTiO3,
and its grain size about 4.85 nm. From dynamic cyclic polarization tests, we can found that dense
BaTiO3 coated effective improved corrosion resistance of Ti substrate than untreated. From
immersion tests, we can found that BaTiO3 exhibited excellent bioactive.
Abstract: The method which gives a low crystalline hydroxyl carbonated apatite forming ability to
originally non-bioactive high crystalline hydroxyapatite surface was newly developed. The granules
of trabecular bovine bone, which had a size range from 212 to 1000 μm, were defatted, deproteinized,
and then heat-treated at 1000 oC for 3 hours to remove organics completely. They were treated with
the mixed solution of calcium chloride and calcium hydroxide in Soxhlet’s apparatus at 100 oC for 3
days and then dried completely. Low crystalline hydroxyl carbonated apatite was observed to occur on
the surface of high crystalline hydroxyapatite granules after soaking them into the simulated body
fluid (SBF) for 1 week. This method is likely to have a potential to be used as a new process to give a
bioactivity to originally non-bioactive materials.
Abstract: After hydrothermal treatment of tricalcium phosphate (TCP), calcium deficient
hydroxyapatite (HA) with much amount of a-surface (h00) was obtained. It was considered that
c-surface of HA had larger surface tension than that of a-surface, therefore HA crystals elongated
along c-axis of <001> directions. By using hydrothermal treatment, difference of surface tension was
affected crystal growth of HA. The adsorption property of HA will be controlled by designing of HA
morphology, because different crystal surfaces have different properties.
Abstract: Stability of hydroxyapatite(HA) structure is influenced by preparation conditions and
afterwards heat treatment. In this paper, the powders with different Ca/P molar ratio were calcined
to investigate the influence of Ca/P and heat treatment on thermal decomposition and reconstitution
of HA. The results show that the Ca/P has little change even calcined at a high temperature of
1500°C. The Ca/P molar ratio close to 1.67 is beneficial to form high purity HA. HA gradually
releases its OH- ions in the temperature range of 800-1200°C. The decomposition takes place at
about 1200°C and will become more and more severe with the increase of temperature. Cooling
with slow rate and post-heat treatment in wet atmosphere are beneficial to both the rehydration and
the recovery of HA from the decomposition products (TTCP and α-TCP).
Abstract: Polyethylene (PE) substrates were irradiated at a dose of 1×1015 ions·cm−2 by the
simultaneous use of oxygen (O2) cluster and monomer ion beams. The acceleration voltage for the
ion beams was 7 kV. Unirradiated and irradiated PE substrates were soaked in simulated body fluid
with ion concentrations 1.5 times of those of human blood plasma (1.5SBF) for 7 days. The irradiated
PE substrate formed apatite on its surface, whereas unirradiated one did not form it. This is attributed
to the formation of functional groups effective for apatite nucleation, such as COOH groups, on the
substrate surface by the simultaneous use of O2 cluster and monomer ion beams. In addition, the
apatite-forming ability of the irradiated substrate was improved by the subsequent CaCl2 treatment.
This suggests that Ca2+ ions present on the substrate surface accelerated the apatite deposition. We
can conclude that apatite-forming ability can be induced on surface of polyethylene by the
simultaneous use of O2 cluster and monomer ion beams.
Abstract: The present study presents the relevance of X-ray diffraction analysis using synchrotron
light in the identification of phases with low intensity peaks. Niobium sheets were coated with
monetite and then converted to hydroxyapatite in an alkali solution. Octacalcium phosphate was
identified as an intermediate phase in the conversion monetite-hydroxyapatite.
Abstract: Calcium-deficient hydroxylapatite (CDHA) powders with Ca/P ratios from1.5 to
1.67 were synthesized by wet-chemical method. Rietveld structure refinement was performed
on the X-ray diffraction data and Fourier transform infrared spectroscopy was used to
characterize molecular and crystal structure of CDHA. With the decrease of Ca/P ratio, the
crystallite size and crystallinity decreased, but the acid phosphate content and amount of
vacancies in hydroxyapatite hexagonal structure increased. The disorder of CDHA structure
increase indicated calcium-deficiency and HPO4 replacement resulted in disorder of crystal in
apatite structure. The more calcium is deficient, the more disorder or imperfect in CDHA