Effect of calcium deficiency on the mechanical properties of hydroxyapatite crystals

Viswanath, B and Shastry, VV and Ramamurty, U and Ravishankar, N (2010) Effect of calcium deficiency on the mechanical properties of hydroxyapatite crystals. In: Acta Materialia, 58 (14). pp. 4841-4848.

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Abstract

The deterioration of the mechanical properties of bone with age is related to several factors including the structure, organization and chemistry of the constituent phases; however, the relative contribution of each of these factors is not well understood. In this study, we have investigated the effect of chemistry (calcium deficiency) on the mechanical properties of single crystals of hydroxyapatite. Single crystals of stoichiometric crystals grown by the flux method and calcium-deficient platelet crystals grown using wet chemical methods were used as model systems. Using nanoindentation, we show that calcium deficiency leads to an 80% reduction in the hardness and elastic modulus and at least a 75% reduction in toughness in plate-shaped hydroxyapatite crystals. Measurement of local mechanical properties using nanoindentation and nanoscale chemistry through elemental mapping in a transmission electron microscope points to a direct correlation between the observed spatial variation in composition and the large scatter in the measured hardness and modulus values. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Item Type:	Journal Article
Publication:	Acta Materialia
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Keywords:	Hydroxyapatite;Calcium deficiency;Nanoindentation;Elastic modulus;Hardness
Department/Centre:	Division of Chemical Sciences > Materials Research Centre Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	03 Aug 2010 06:50
Last Modified:	19 Sep 2010 06:13
URI:	http://eprints.iisc.ac.in/id/eprint/31098

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