Rietveld Refinement of Sintered Magnesium Substituted Calcium Apatite

Abstract

The incorporation of magnesium in the synthetic apatite has been associated with biomineralization process and osteoporosis therapy in human and animals. Magnesium easily replaces calcium in the apatite lattice and influences or controls the hydroxyapatite crystallization processes. In this work, Mg-substituted calcium deficient apatite, with Mg/Ca ratio = 0.1, 0.15 and 0.2 were synthesized by precipitation method. Then, sintered at 1000 oC and compared with a commercial product labeled as tricalcium phosphate sintered at the 1000 oC. The sintered products showed tricalcium phosphate (β-TCP) structure. The Mg2+ substitution in the Ca(4) and Ca(5) sites of β-TCP and the lattice parameter changes were estimated using the Rietveld method. Using this method, the formulas Ca2.73(Mg0.27)(PO4)2, Ca2.71(Mg0.29)(PO4)2 and Ca2.70(Mg0.23Mg0.07)(PO4)2 were calculated for the samples with Mg/Ca ratio = 0.1, 0.15 and 0.2 respectively.

Substituted hydroxyapatites for biomedical applications: A review

“…Syntheses in bulk were realized by a precipitation method [46,71,172,173,[175][176][177][178][179][180][181][182][183][184][185][186], by sol-gel [187][188][189], in the presence of low molecular PAA [120], by the mechanochemical-hydrothermal route [174], by surfactantassisted microwave synthesis [190], by wet mixing [191] or by melting and extrusion [192].…”

“…different methods for preparing HA-like materials would probably result in different levels of hydration and possibly other defects in the materials.Changes in lattice parameters due to substitution have a direct impact on the properties of Mg-HA, compared to their non-substituted analogues[47,172,174,178]: the changes notably increase their solubility and biodegradability in physiological fluids, and favour their thermal conversion into Mg-substituted ß-tricalcium phosphate (ß-Ca 3-x Mg x (PO 4 ) 2 )[185,186].Cacciotti et al[179] studied the effect of Mg substitution on sinterability, and they proved that Mg incorporation induced increased residual porosity. The influence of Mg concentration (up to 1.8 wt.%) on the mechanical properties of Mg-HA was the topic of a detailed study by…”

Doped biphasic calcium phosphate: synthesis and structure

“…The synthesized doped material becomes completely amorphous in nature when the Mg content reaches above 35 atom% [172]. On the other hand, Mg-substitution favors thermal conversion of HA into β-TCP [176]. Zyman et al [177] explored the mechanical properties of Mg-doped HA, and found a decline in its compressive strength and microhardness, together with an increment in fracture toughness.…”

Incorporation of carbonate and magnesium ions into synthetic hydroxyapatite: The effect on physicochemical properties

“…Although several articles have already been published on the physicochemical properties of fluorapatites, carbonate-containing apatites and apatites with substituted and/or adsorbed various cations [1][2][3][4], only a few works were devoted to careful investigation of Mg 2+ -doped hydroxyapatite (Mg-HA) [5,8,[12][13][14][15][16][17][18] and Mg 2þ =CO 2À 3 co-substituted hydroxyapatite (Mg-CHA) [10,[19][20][21][22][23][24][25][26]. They reported various methods of the Mg-CHA syntheses, leading to various CO 2À 3 and Mg 2+ concentrations and different distributions of those ions between the crystal surface and the crystal lattice.…”