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Synthesis and Optimization of the Production of Millimeter‐Sized Hydroxyapatite Single Crystals by Cl − – OH − Ion Exchange
Author(s) -
GarcíaTuñon Esther,
Franco Jaime,
Eslava Salvador,
Bhakhri Vineet,
Saiz Eduardo,
Giuliani Finn,
Guitián Francisco
Publication year - 2013
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.12199
Subject(s) - nanoindentation , apatite , materials science , fourier transform infrared spectroscopy , ion exchange , ion , infrared spectroscopy , analytical chemistry (journal) , mineralogy , crystallography , chemical engineering , nuclear chemistry , chemistry , composite material , organic chemistry , chromatography , engineering
Millimeter‐sized hydroxyapatite ( HA ) single crystals were synthesized from chlorapatite ( ClAp ) crystals via the ionic exchange of Cl − for OH − at high temperature. X‐ray diffraction, Fourier‐transform infrared spectroscopy, and chloride content measurements were used to follow the progress of this conversion, and to assess the effect of the experimental conditions (temperature, time, and atmosphere). Cl − → OH − exchange took place homogeneously and was enhanced by firing in wet air. After firing at 1425°C for 2 h 92% of the Cl − ions were exchanged by OH − while maintaining crystal integrity. Temperatures above 1450°C damaged the surface of the crystals, destroying the hexagonal habit at 1500°C. The composition of these apatite crystals was close to bone mineral content. Their nanoindentation hardness (8.7 ± 1.0 GPa) and elastic nanoindentation modulus (120 ± 10 GPa) were similar to those of the starting ClAp (6.6 ± 1.5 GPa, and 110 ± 15 GPa, respectively). However, their average flexural strength was ~25% lower due to the formation of defects during the thermal treatments.