Synthesis of nano hydroxyapatite powder that simulate teeth particle morphology and composition

K.P. Sanosh,Min-Cheol Chu,A. Balakrishnan,Yong-Jin Lee,T.N. Kim,Seong-Jai Cho 한국물리학회 2009 Current Applied Physics Vol.9 No.6

A simple sol–gel precipitation technique to synthesize nano hydroxyapatite (HA) particles (~30 nm) that show similar morphology, size and crystallinity to HA crystals of human teeth is reported. Calcium nitrate tetrahydrate and potassium dihydrogenphosphate were used as calcium and phosphorus precursors, respectively. Double distilled water was used as a diluting media for HA sol preparation and ammonia was used to adjust the pH to 11. After aging, the HA gel was dried at 40 ℃ and calcined to different temperatures ranging from 200 to 600 ℃. The dried and calcined powders were characterized for phase composition using X-ray diffractrometry, and Fourier transform infra-red spectroscopy. The particle size and morphology was studied using Transmission electron microscopy. The particle size distribution analysis of HA powders showed skewed distribution plot. The phase and particle characterization studied above showed that HA calcined at 600 ℃ simulate HA crystals of teeth. A simple sol–gel precipitation technique to synthesize nano hydroxyapatite (HA) particles (~30 nm) that show similar morphology, size and crystallinity to HA crystals of human teeth is reported. Calcium nitrate tetrahydrate and potassium dihydrogenphosphate were used as calcium and phosphorus precursors, respectively. Double distilled water was used as a diluting media for HA sol preparation and ammonia was used to adjust the pH to 11. After aging, the HA gel was dried at 40 ℃ and calcined to different temperatures ranging from 200 to 600 ℃. The dried and calcined powders were characterized for phase composition using X-ray diffractrometry, and Fourier transform infra-red spectroscopy. The particle size and morphology was studied using Transmission electron microscopy. The particle size distribution analysis of HA powders showed skewed distribution plot. The phase and particle characterization studied above showed that HA calcined at 600 ℃ simulate HA crystals of teeth.

Sol-gel synthesis of pure nano sized β-tricalcium phosphate crystalline powders

K.P. Sanosh,Min-Cheol Chu,A. Balakrishnan,T.N. Kim,Seong-Jai Cho 한국물리학회 2010 Current Applied Physics Vol.10 No.1

β-Tricalcium phosphate (β-TCP) nano powders (~80 nm) were synthesized using a simple sol.gel route with calcium nitrate and potassium dihydrogenphosphate as calcium and phosphorus precursors, respectively. Double distilled water was used as a diluting media for β-TCP sol preparation and ammonia was used to adjust the pH. After aging, the β-TCP gel was dried at 40 ℃ and calcined to different temperatures ranging from 200 to 800 ℃. The dried and calcined powders were characterized for phase composition using X-ray diffractrometry (XRD) and Fourier transform-infrared spectroscopy (FT-IR). The particle size and morphology was studied using Transmission electron microscopy (TEM). Calcination revealed that with increase in temperature, both the crystallinity and crystallite size of β-TCP particles increased. Particle size distribution analysis of the calcined β-TCP at 800 ℃ showed a narrow skewed distribution plot centered between 70 and 80 nm. This value was in closed agreement with particle size values obtained from XRD analysis (83 ± 6 nm). The present study showed that narrowly distributed, high crystalline,pure β-TCP could be obtained using this simple technique for biomedical applications.

Sol-gel synthesis of pure nano sized β-tricalcium phosphate crystalline powders

Sanosh, K.P.,Chu, M.C.,Balakrishnan, A.,Kim, T.N.,Cho, S.J. Elsevier 2010 CURRENT APPLIED PHYSICS Vol.10 No.1

β-Tricalcium phosphate (β-TCP) nano powders (∼80nm) were synthesized using a simple sol-gel route with calcium nitrate and potassium dihydrogenphosphate as calcium and phosphorus precursors, respectively. Double distilled water was used as a diluting media for β-TCP sol preparation and ammonia was used to adjust the pH. After aging, the β-TCP gel was dried at 40<SUP>o</SUP>C and calcined to different temperatures ranging from 200 to 800<SUP>o</SUP>C. The dried and calcined powders were characterized for phase composition using X-ray diffractrometry (XRD) and Fourier transform-infrared spectroscopy (FT-IR). The particle size and morphology was studied using Transmission electron microscopy (TEM). Calcination revealed that with increase in temperature, both the crystallinity and crystallite size of β-TCP particles increased. Particle size distribution analysis of the calcined β-TCP at 800<SUP>o</SUP>C showed a narrow skewed distribution plot centered between 70 and 80nm. This value was in closed agreement with particle size values obtained from XRD analysis (83+/-6nm). The present study showed that narrowly distributed, high crystalline, pure β-TCP could be obtained using this simple technique for biomedical applications.

Synthesis of nano hydroxyapatite powder that simulate teeth particle morphology and composition

Sanosh, K.P.,Chu, M.C.,Balakrishnan, A.,Lee, Y.J.,Kim, T.N.,Cho, S.J. Elsevier 2009 CURRENT APPLIED PHYSICS Vol.9 No.6

A simple sol-gel precipitation technique to synthesize nano hydroxyapatite (HA) particles (∼30nm) that show similar morphology, size and crystallinity to HA crystals of human teeth is reported. Calcium nitrate tetrahydrate and potassium dihydrogenphosphate were used as calcium and phosphorus precursors, respectively. Double distilled water was used as a diluting media for HA sol preparation and ammonia was used to adjust the pH to 11. After aging, the HA gel was dried at 40<SUP>o</SUP>C and calcined to different temperatures ranging from 200 to 600<SUP>o</SUP>C. The dried and calcined powders were characterized for phase composition using X-ray diffractrometry, and Fourier transform infra-red spectroscopy. The particle size and morphology was studied using Transmission electron microscopy. The particle size distribution analysis of HA powders showed skewed distribution plot. The phase and particle characterization studied above showed that HA calcined at 600<SUP>o</SUP>C simulate HA crystals of teeth.

Pressureless Sintering of Nanocrystalline Hydroxyapatite at Different Temperatures

K. P. Sanosh,추민철,A. Balakrishnan,김택남,조성재 대한금속·재료학회 2010 METALS AND MATERIALS International Vol.16 No.4

In this work, the sintering behaviour of hydroxyapatite (HA) at different temperatures was studied. Nano HA powders synthesized by sol-gel technique were uniaxially pressed at 30 MPa into pellets and cold isostatically pressed at 200 MPa. The pellets were sintered in air at temperatures ranging from 900 °C to 1400 °C with a holding time of 2 h. It was observed that, at a sintering temperature of 1200 °C when the material was composed of pure HA phase, the samples exhibited densities of > 98.5 % of the theoretical value and possessed a hardness value of 5.89 GPa. Decomposition of HA into the secondary phases of TCP and CaO was found to occur at 1300 °C and 1400 °C, respectively. Changes in the microstructure, relative density and hardness of the sintered HA ceramics with the sintering temperature were also analyzed. The variation in the hardness was found to be dependent on the relative density up to a threshold grain size limit of 2 μm. However,beyond this threshold, no correlation existed between the two properties. Porosity and grain size were found to play an important role in determining the properties of the sintered HA compacts.

Mechanical properties of MgO–Al₂O₃–SiO₂ glass-infiltrated Al₂O₃–ZrO₂ composite

Balakrishnan, A.,Panigrahi, B.B.,Sanosh, K.P.,Chu, Min-Cheol,Kim, T.N.,Cho, Seong-Jai Elsevier 2009 Journal of materials processing technology Vol. No.

<P><B>Abstract</B></P><P>This work attempts to improve the mechanical properties of alumina-10wt% zirconia (3mol% yttria stabilized) composite by infiltrating a glass (magnesium aluminum silicate glass) of lower thermal expansion on the surface at high temperature. The glass improved the strength of the composite at room temperature as well as at higher temperatures. There was a significant improvement in the Weibull modulus after the glass infiltration. Glass-infiltrated samples showed better thermal shock resistance. The magnitude of strength increment was found to be in the order of the surface residual stress generated by thermo-elastic properties mismatch between the composite and the infiltrated glass.</P>

Effect of high thermal expansion glass infiltration on mechanical properties of alumina-zirconia composite

Balakrishnan, A.,Panigrahi, B. B.,Sanosh, K. P.,Chu, Min-Cheol,Kim, T. N.,Cho, Seong-Jai Springer-Verlag 2009 Bulletin of materials science Vol.32 No.4