Microwave accelerated synthesis of nanosized calcium deficient hydroxyapatite

Abstract

Rapid synthesis of calcium deficient hydroxyapatite (CDHA, Ca(10-x)(HPO4)x(PO4)(6-x)(OH)(2-x)) with Ca/P ratio 1.5 was done by precipitation using calcium nitrate tetra-hydrate and phosphoric acid and subsequently subjecting to microwave irradiation in a domestic microwave oven for 15 min. Transmission electron microscopy analysis shows needle like morphology of CDHA having length 16-39 nm and width 7-16 nm. The synthesized CDHA has the characteristic HPO4(2-) vibration band at 875 cm(-1) in Fourier transform infrared (FT-IR) spectra. The X-ray powder diffraction (XRD) analysis shows a pattern corresponding to stoichiometric hydroxyapatite (HA) with broad peaks suggesting that CDHA particles were nanosized. Fourier transform Raman spectroscopy (FT-Raman) do not indicate any fluorescence band that is characteristic of non-stoichiometric HA. The thermal decomposition of CDHA to beta tricalcium phosphate (beta-TCP) was also studied for the additional confirmation. The nanosized CDHA was found to be stable up to 600 degrees C.

Luminescence properties of Eu2+ and Eu3+ doped calcium-deficient hydroxyapatite prepared in air

“…These Eu-doped calcium-deficient hydroxyapatite powders, designated as CDHA:Eu, possessed a hexagonal symmetry. The calculated lattice parameters of CDHA:Eu were a = 9.425Å and c = 6.880Å, which agree with those of CDHA reported by Siddharthan et al [9]. The coprecipitated CDHA:Eu powders were consisted of crystalline spherical nanoparticles in a size range of 50-150 nm as shown in Fig.…”

Calcium orthophosphates (CaPO 4 ): Occurrence and properties

“…Besides, it might be prepared by hydrolysis of a-TCP (TenHuisen and Brown 1998;Durucan andBrown 2000, 2002). Other preparation techniques of CDHA are known as well (Vallet-Regí et al 1997;Siddharthan et al 2004;Hutchens et al 2006;Mochales et al 2011). During aging, initially precipitated ACPs are restructured and transformed into CDHA.…”

F-substituted hydroxyapatite nanopowders: Thermal stability, sintering behaviour and mechanical properties

“…1.541 Å for Cu Ka radiation), u is the Bragg's diffraction angle (in degrees) and v is the full width at half maximum (FWHM). The diffraction peak at 25.88 (2u) corresponding to the (0 0 2) Miller plane family of HAp (JCPDS files #09-0432), and the diffraction peak at 32.98 (2u) corresponding to the (3 0 0) Miller plane family, were chosen to calculate the average crystal size along to the crystallographic axis c and a, respectively, v 0 corresponds to the instrumental width [19]. Cell parameters of pure and substituted HAps were estimated through the algorithm TREOR (Philips X'Pert Plus software).…”