Sol–gel synthesis and characterization of hydroxyapatite nanorods (original) (raw)
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Preparation and characterization of nano-hydroxyapatite powder using sol-gel technique
Bulletin of Materials Science, 2009
Hydroxyapatite (HA) nano powders (20-60 nm) were synthesized using a sol-gel route with calcium nitrate and phosphoric acid 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. After aging, the HA gel was dried at 65°C and calcined to different temperatures ranging from 200-800°C. The dried and calcined powders were characterized for phase composition using X-ray diffractometry, elemental dispersive X-ray and Fourier transform infra-red spectroscopy. The particle size and morphology were studied using transmission electron microscopy. Calcination revealed HA nano powders of increased particle size and crystallinity with increase in temperature. For all calcinations temperatures, the particle size distribution analysis of HA powders showed skewed distribution plot. At temperature of 700°C and above, formation of CaO was noticed which was attributed to phosphorous volatilization. This study showed that high purity HA with varying degrees of crystallinity could be obtained using this simple technique.
Low temperature synthesis of hydroxyapatite nano-rods by a modified sol–gel technique
Materials Science and Engineering: C, 2011
Hydroxyapatite (HAp) nano-rods were successfully synthesized by a modified sol-gel method using a solution of CaCl 2 ·2H 2 O in water, along with a solution of H 3 PO 4 in triethylamine and NH 4 OH as starting materials. The Ca/P molar ratio was maintained at 1.67. The sol obtained was dried in an oven for 2 days at 100°C after being dialyzed for 12 h. Pellets were made from the crystalline powders and immersed in simulated body fluid (SBF) to check its biocompatibility after 15, 45 and 180 days of immersion. The HAp powders and pellets were characterized by X-Ray Diffraction crystallography (XRD), Fourier transform Infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Transmission electron microscopy (TEM). The HAp nano-rods had an average diameter of 25 nm and length 110-120 nm. Immersion of the HAp pellets in SBF led to the formation of a highly porous interconnecting HAp layer on the surface. The porosity increased with increase in immersion time.
Physico-chemical properties of nano-sized hexagonal hydroxyapatite powder synthesized by sol-gel
2010
Calcium phosphate ceramic powders were synthesized via sol-gel method. The powders were sintered at 600 and 1000°C and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron microscopy (SEM and TEM), elemental microanalysis (EDS), infrared spectroscopy (FTIR), and thermal analysis (TGA and DTA). The XRD analysis revealed a well crystallized hydroxyapatite (HAp) structure at all temperatures. At 1000°C a small amount of CaO (about 1.2 %) was detected. The average crystallite size increased from 19 nm at 80 o C to about 125 nm at 1000 o C. FTIR spectra showed the presence of various and OHgroups present in the powders. In order to verify the biocompatibility of HAP powders with hFOB 1.19 osteoblasts cells, an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test was applied. It was noticed that the ceramics obtained at 1000ºC, increased the cell viability with 10%, 40% and 55% after 6, 12 respectively 24 h, whereas that obtained at 600 ºC was less effective. Our results proved the high biocompatibility of calcium phosphate ceramic powders obtained by sol-gel and sintered at 1000ºC. − 3 4 PO
Materials Letters, 2007
Many attempts have been focused on preparing of synthetic hydroxyapatite (HA), which closely resembles bone apatite and exhibits excellent osteoconductivity. Low temperature formation and fusion of the apatite crystals have been the main contributions of the sol-gel process in comparison with conventional methods for HA powder synthesis. This paper describes the synthesis of nano-HA particles via a sol-gel method. Nanocrystalline powder of hydroxyapatite (HA) was prepared using Ca(NO 3 ) 2 ·4H 2 O and P 2 O 5 by a simple sol-gel approach. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used for characterization and evaluation of the phase composition, morphology and particle size of products. The presence of amorphous and crystalline phases in the as-dried gel precursor was confirmed by the evaluating technique. Single phase of HA was also identified in the heat treated powder by XRD patterns. SEM and TEM evaluations showed that the obtained powder after heat treatment at 600°C was agglomerated and composed of nanocrystalline (25-28 nm) HA particles. Increasing the sintering temperature and time could cause decomposition of HA into β-tricalcium phosphate and calcium oxide. The prepared nanocrystalline HA is able to improve the contact reaction and the stability at the artificial/natural bone interface for medical applications.
Hydroxyapatite nanopowders obtained by sol-gel method, synthesis and properties
The present paper deals with sol-gel preparation of hydroxyapatite powders for bio uses by performing several techniques of gelation and thermal treatments of dried gels. The hydroxyapatite formation and decomposition are checked by X-ray diffraction which showed that the tri-calcium phosphate apparition takes place as the result of thermal treatment at 700oC. The Fourier Transform Infrared spectra confirm the hydroxyapatite apparition and also the carbonyl disappearance at 900oC, which is responsible for the grey color of the powdered sample. SEM pictures showed spherique particles with narrow distribution, in the range of 35-50 nm dimensions.
Materials Today: Proceedings, 2017
Hydroxyapatite is also commonly known as Hap which has hexagonal structure, its chemical formula is Ca 5 (PO 4) 3 (OH) and its empirical formula increased by 2times of the chemical formula. Molecular weight of HAP is 502.31gm, hardness is 5 and density of HAp is 3.08. HAp is naturally available but only disadvantages is contains the impurities which is not suitable for biomedical application so researchers are interested to produce pure HAp by artificially. So only numerous process are introduced like Molten salt solution, coprecipitation, hydrothermal, solvo thermal, solution combustion, wet chemical method and precipitation process etc. sol-gel process is chosen in the present work. Raw material is used Calcium chloride and Phosphoric acid. The as prepared HAp nano powder is sintered in the muffle furnace and microwave sintering at 800 o C and Melting temperature of HAp is 1250 o C. It has vast applications in the field of bio medical such as implants of bone, bone tissue, ear, eye and dental application because of its good biocompatibility. In both the cases particle size were as low as 30 nm to 80 nm have been measured and calculated manually. The complete phase of Ca 10 (PO 4) 6 (OH) 2 has been identified by X-ray Diffraction pattern some of the peaks matches with JCPDS data 09-0432. More details are discussed in detail about the formation of Ca 10 (PO 4) 6 (OH) 2 and their morphological behaviour under different parameters
Influence of particle size and morphology of chemically modified hydroxyapatite by sol-gel method
Hydroxyapatite (HAP) is an inorganic compound with the chemical formula of Ca10(PO4)6(OH)2. It has been recognized as a substitute material for bone and teeth in orthopedics and dentistry due to their chemical and biological similarity to human hard tissue. Synthetic nano-sized HAP particles exhibit favorable biocompatibility and bioactivity and in order to better match the composition to natural HAP there is a great interest in producing a range of chemically modified hydroxyapatite powders. In this study, three different powders have been synthesized via an ethanol-based sol-gel method. Calcium nitrate tetra hydrate and P2O5 were employed as calcium and phosphorus precursors respectively. An aqueous solution of Ammonium hydroxide was added as dispersing agents to the reaction mixture. Separately, sodium hydroxide was added as a dispersing agent and the pH of the solution was modified as 10.5. Subsequent powder calcinations have been carried out within the temperature range of 900 °C and the resultant powders were characterized by AAS, Powder-XRD, FT-IR and SEM analysis. Keywords: Hydroxyapatite, Glass ceramic, SEM, particle size, dispersing agent.
Synthesis of Hydroxyapatite Nanopowders via Sucrose-Templated Sol-Gel Method
Journal of the American Ceramic Society, 2003
The present research describes synthesis of hydroxyapatite (HAp) nanopowders using a sol-gel route with calcium nitrate and ammonium hydrogen phosphate as calcium and phosphorous precursors, respectively. Sucrose is used as template material, and alumina is added as a dopant to study its effects on particle size and surface area. Synthesized powders are characterized using X-ray diffractometry, BET surface-area analysis, and transmission electron microscopy. Results show that alumina stabilizes the HAp crystalline phase. Average particle size of mesoporous HAp samples is between 30 and 50 nm with surface area of 51-60 m 2 /g.
Powder Technology, 2013
Hydroxyapatite is a class of calcium phosphate-based bioceramic, frequently used as a bone graft substitute due to its chemical and structural similarity with natural bone mineral. In the present investigation, a novel method is developed to synthesize pure, stable, stoichiometric nano crystalline hydroxyapatite (HA: Ca 10 (PO 4 ) 6 (OH) 2 ) at room temperature via alcohol based sol-gel route using Ca(NO 3 ) 2 .4H 2 O and NH 4 H 2 PO 4 as calcium and phosphorous precursors, respectively. We have developed a novel method for the synthesis of nanometer sized HA particles (HAp) without using any catalyst and was synthesized without any grinding process during the gel formation. Polycrystalline HAp synthesized by this new technique is characterized by XRD, FTIR, TGA, SEM and TEM.
In this study nano crystalline hydroxyapatite (HA) particles were produced by both sol-gel and precipitation methods. For this purpose calcium nitrate tetra hydrate (Ca(NO3)2•4H2O) was selected as calcium precursors and three types of phosphorus precursors such as acid phosphoric (H3PO4) , triethyl phosphate (C2H5O)3PO and pentad oxide phosphorus (P2O5) were chosen. The produced powders were characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results show that although hydroxyapatite can be produced by all phosphorus precursors used in the current research, the purity of HA obtained from penta oxide phosphorus and phosphoric acid is higher than that of triethyl phosphate. The SEM micrographs prove that the morphology of nano-HAP depends on the type of phosphorus precursor .The HAP prepared from acid phosphoric was spherically shaped whereas the one from triethyl phosphate is needle like and from penta oxide phosphorus was found to be Pyramidal in shape.