Showing papers by "A. Ruban Kumar published in 2010"

Sol-gel synthesis of nanostructured hydroxyapatite powder in presence of polyethylene glycol

Abstract: A study on the morphological changes of nanostructured hydroxyapatite in presence of polyethylene glycol synthesized by sol–gel technique is presented. Equimolar solutions of Ca(NO 3 ) 2 ·4H 2 O and (NH 4 ) 2 HPO 4 dissolved in ethanol were used in the synthesis at 85 °C. Polyethylene glycol is added as an organic modifier. The product was sintered at 400, 750 and 1100 °C. The XRD and FTIR results indicated the presence of amorphous hydroxyapatite in as dried gel precursor and single phase HAP was obtained after heat treatment at 1100 °C at 4 h. SEM images of the precursor appear agglomerated leaving sub micrometric pores between them and the small particles seen embedded in each agglomerated cluster with an average diameter of 50–70 nm. At high temperatures the more flexible polyethylene glycol molecules induced the orientation growth which leads to the formation of HAP platelets.

Microwave assisted synthesis of hydroxyapatite nano strips

Abstract: Synthesis of hydroxyapatite (HAP) nano strips was carried out by chemical precipitation method followed by microwave irradiation. The microwave assisted reactions proceed at fast rates. It is found that the presence of the complex reagent EDTA plays an important role in the morphological changes of nanostructure hydroxyapatite. EDTA acts as a hexadentate unit by wrapping itself around the Ca2+ metal ion with, four oxygen and two nitrogen atoms and forms several five member chelate rings. The relative specific surface energies associated with the facets of the crystal determines the shape of the crystal. Scanning electron microscopy revealed the presence of hydroxyapatite nano strips with the range 50-100 nm in EDTA influenced HAP powders. Fourier transform-infrared spectroscopy (FT-IR) result combined with the X-ray diffraction (XRD) indicates the presence of amorphous hydroxyapatite (HAP) in the as-prepared material. X-ray patterns collected on the powder after heat-treatment at 1100 °C for 2 h in air exhibits single phase of HAP. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)