Weeraphat Pon-OnSiwaporn MeejooI. Ming TangMahidol UniversityThe Institute of Science and Technology for Research and Development, Mahidol University2018-08-242018-08-242007-02-01International Journal of Nanoscience. Vol.6, No.1 (2007), 9-160219581X2-s2.0-34047201153https://repository.li.mahidol.ac.th/handle/20.500.14594/24252This research focuses on understanding the nature of the Fe ions substituted in hydroxyapatite ((HAP) Ca10-xFex(PO4)6(OH)2-xÿx: x = 0, 0.2 and 0.4) powder synthesized at temperatures between 500°C and 1000°C and their crystallization. The DSC scan indicates a solid state phase transition at about 757°C for the as-prepared powder HAP. The transformation of HAP to β-tricalcium phosphate (β-TCP, β-Ca3(PO4)2) is seen when the powder were heated to 750°C. The sizes of the crystallites were determined to be about 46-51 nm, 33-40nm and 33-59 nm for Fe content of 0, 0.2 and 0.4mol%, respectively. The ESR parameters for the Fe3+ions, g = 4.23 and 8.93 indicated that the ions were subjected to a rhombic ion crystal field within the HAP structures. The g values of ∼2.01 indicated that the particles were super-paramagnetic and ferromagnetic iron nanoparticles, having an average size about 0.2-0.5 μm in length. © World Scientific Publishing Company.Mahidol UniversityBiochemistry, Genetics and Molecular BiologyChemical EngineeringComputer ScienceEngineeringMaterials SciencePhysics and AstronomyArticleSCOPUS10.1142/S0219581X07004262