title: Effect of precursor concentration and spray pyrolysis temperature upon hydroxyapatite particle size and density.
abstract: In the synthesis of hydroxyapatite powders by spray pyrolysis, control of the particle size was investigated by varying the initial concentration of the precursor solution and the pyrolysis temperature. Calcium phosphate solutions (Ca/P ratio of 1.67) with a range of concentrations from 0.1 to 2.0 mol/L were prepared by dissolving calcium nitrate tetrahydrate and diammonium hydrogen phosphate in deionized water and subsequently adding nitric acid. Hydroxyapatite powders were then synthesized by spray pyrolysis at 900°C and at 1500°C, using these calcium phosphate precursor solutions, under the fixed carrier gas flow rate of 10 L/min. The particle size decreased as the precursor concentration decreased and the spray pyrolysis temperature increased. Sinterability tests conducted at 1100°C for 1 h showed that the smaller and denser the particles were, the higher the relative densities were of sintered hydroxyapatite disks formed from these particles. The practical implication of these results is that highly sinterable small and dense hydroxyapatite particles can be synthesized by means of spray pyrolysis using a low-concentration precursor solution and a high pyrolysis temperature under a fixed carrier gas flow rate.
authors.affiliation: Interdisciplinary Program of Bioengineering, College of Engineering, Seoul National University, Seoul, 152-742, Korea.
authors.forename: Jung Sang
authors.initials: JS
authors.lastname: Cho
authors.affiliation: Department of Dental Biomaterials Science, Dental Research Institute & BK21 HLS Plus, School of Dentistry, Seoul National University, Daehakro 101, Jongno, Seoul, 110-749, Korea.
authors.forename: Jeong-Cheol
authors.initials: JC
authors.lastname: Lee
authors.affiliation: Interdisciplinary Program of Bioengineering, College of Engineering, Seoul National University, Seoul, 152-742, Korea.|Department of Dental Biomaterials Science, Dental Research Institute & BK21 HLS Plus, School of Dentistry, Seoul National University, Daehakro 101, Jongno, Seoul, 110-749, Korea.
authors.forename: Sang-Hoon
authors.initials: SH
authors.lastname: Rhee
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry*; D017886:Durapatite / Q000737:chemistry*; D006358:Hot Temperature; D009566:Nitrates / Q000737:chemistry*; D010316:Particle Size; D011208:Powders
chemical_list: D017610:Calcium Compounds; D009566:Nitrates; D011208:Powders; D017886:Durapatite; C059948:calcium nitrate
keywords: concentration; hydroxyapatite; particle size; sinterability; spray pyrolysis