Sintering and Mechanical Properties of Magnesium and Fluorine Co-Substituted Hydroxyapatites

Nsar, S.; Hassine, A. Ben; Bouzouita, Khaled

doi:10.4236/jbnb.2013.41001

Cited by 9 publications

(7 citation statements)

References 45 publications

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“…The a variation was governed by two antagonist effects: firstly, the substitution of K + (0.138 nm) for Ca 2+ (0.100 nm) induced an increase in the a values; however, as it was reported in the literature, the substitution of a divalent cation by a monovalent one decreased the channel diameter of a parameter and in consequence, a markedly decreased [28,29,31]. Secondly, the bibliography on hydroxfluorapatites reported that a parameter increased with a decreasing degree of fluoridation [36,37]. In present work, a contraction of the lattice parameters suggested was attributed to K + substitution.…”

Section: Phase Analysismentioning

confidence: 82%

Sintering of Potassium Doped Hydroxy-Fluorapatite Bioceramics

et al. 2021

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The present study describes the influence of potassium and hydroxyl substitutions on the structural, thermal and mechanical properties of fluorapatite bioceramics. A set of non-stoichiometric ion-substituted compounds, with a chemical formula of Ca10−xKx(PO4)6F(2−2x)(OH)x with 0 ≤ x ≤ 1 synthesized by the wet precipitation method, were found to be single-phase apatites crystallizing in the hexagonal P63/m space group. The structural parameters, as well as the crystallite sizes, increased accordingly to the amount of added dopant-ions. The thermal behavior of these compounds, studied within the temperature range 500–1200 °C, indicated a partial decomposition of the apatitic phase and its transformation to tricalcium phosphate β-Ca3(PO4)2 at temperatures exceeding 750 °C. A relative density of the sintered samples achieved the highest value with x = 0.25 and reached about 95% after sintering at 1050 °C for 1 h. The microstructures of the sintered samples were of a trans-granular aspect and experienced an increase in the radius of their pores as x increased. The prepared bioceramic materials were mechanically characterized by means of Young’s modulus, flexural strength and fracture toughness measurements. The overall trend of these parameters evolved comparably to the relative density, and the maximum values obtained for x = 0.25 were measured to be 96 MPa, 47 MPa and 1.14 MPa·m1/2, respectively.

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Section: Phase Analysismentioning

confidence: 82%

Sintering of Potassium Doped Hydroxy-Fluorapatite Bioceramics

et al. 2021

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“…[20][21][22] Sheline [23] confirmed that the molten magnesium fluoride facilitates the decomposition of magnesia by investigating the electrolytic production of Mg from MgO both experimentally and theoretically. Wang [24] provided experimental evidence that magnesium fluoride is generated during the reduction of magnesia with 3 wt pct CaF 2 .…”

Section: Role Of Fluorine and Calcium Ionsmentioning

confidence: 89%

Mechanism of Calcium Fluoride Acceleration for Vacuum Carbothermic Reduction of Magnesia

Jiang

Liu

et al. 2015

Metall Mater Trans B

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The use of a small amount of calcium fluoride as an additive greatly accelerated the reduction of magnesia during the preparation of magnesium from magnesia using the vacuum carbothermic reduction method. At 1573 K (1300°C), the magnesia reaction rates of the samples with 1, 3, and 5 pct CaF 2 were all approximately 26 pct, three times that of free CaF 2 , and they were arranged in order of the calcium fluoride weight percentages at 1673 K (1400°C). The residues were analyzed using chemical analysis, XRD, SEM, EDS, and XRF. The possible acceleration mechanism was discussed. Calcium fluoride combined with magnesia and silicon dioxide to form a eutectic that melted as a channel to aid the solid-solid reaction between carbon and magnesia at approximately 1573 K (1300°C). Calcium fluoride in the molten state offered free calcium ions and fluorine ions. Fluorine ions entered and distorted the magnesia crystal lattice. The structural strength and chemical stability of the magnesia crystal lattice decreased, which facilitated the magnesia reduction by carbon. Calcium ions were employed to generate the calcium and magnesium silicate. The easyly evaporating fluorides, including magnesium fluoride and silicon tetrafluoride, were regarded as the main reason for the loss of fluorine.

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“…On the other hand, F − was combined with Ag + , Mg 2+ and Y 3+ in order to be co‐substituted within apatite lattice. Turkoz et al synthesised silver and fluoride doped hydroxyapatites by precipitation and verified that small amount of dopings resulted in high densities and fine grain microstructures, and that Ag + and F − ions incorporation led to increased microhardness values with respect to undoped HAp.…”

Section: Bi‐substituted Hydroxyapatite Powdersmentioning

confidence: 99%

“…Turkoz et al synthesised silver and fluoride doped hydroxyapatites by precipitation and verified that small amount of dopings resulted in high densities and fine grain microstructures, and that Ag + and F − ions incorporation led to increased microhardness values with respect to undoped HAp. Nsar et al produced magnesium and fluorine co‐substituted hydroxyapatites (Ca 9 Mg(PO 4 ) 6 (OH) 2− y F y , where y = 0, 0.5, 1.0, 1.5 and 2.0) by the hydrothermal method. They highlighted that the thermal stability, microstructure, sinterability, and mechanical properties strongly depend on the temperature of the thermal treatment and on the fluorine amount.…”

Section: Bi‐substituted Hydroxyapatite Powdersmentioning

confidence: 99%

Multisubstituted hydroxyapatite powders and coatings: The influence of the codoping on the hydroxyapatite performances

Cacciotti

2019

Int J Applied Ceramic Tech

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The biological apatite, whose the bone and teeth mineral phases are composed, remarkably differs from stoichiometric hydroxyapatite (HAp, Ca10(PO4)6(OH)2, Ca/P = 1.667). Indeed, it consists in carbonated Ca‐deficient (Ca/P < 1.667) apatite, characterised by the presence of several vicarious ions, either incorporated within the apatite lattice or just adsorbed on the crystal surface, including anionic (eg, F−, Cl−, SiO44- and CO3=) and/or cationic substitutions (eg, Na+, Mg2+, K+, Sr2+, Zn2+, Ba2+, Al3+). For this reason, recently, a continuous and rising attention has been devoted to the ionic substitutions within the hydroxyapatite lattice in order to resemble the chemical composition of the bone mineral component and to improve its chemical, physical and mostly biological properties, for applications in biomedical sector, particularly in dentistry, orthopaedics and bone tissue engineering. The present manuscript provides a complete overview about the bi‐substituted hydroxyapatites in form of powders and coatings, in order to evidence the effect of the co‐doping with different vicarious ions within HAp lattice on its physicochemical properties, such as microstructure, morphology, thermal stability, solubility, thermal decomposition, dissolution, grain size, mechanical strength, degradation kinetics, corrosion resistance, and biological responsiveness, in terms of in vitro bioactivity, cytotoxicity and antibacterial action.

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Sintering and Mechanical Properties of Magnesium and Fluorine Co-Substituted Hydroxyapatites

Cited by 9 publications

References 45 publications

Sintering of Potassium Doped Hydroxy-Fluorapatite Bioceramics

Sintering of Potassium Doped Hydroxy-Fluorapatite Bioceramics

Mechanism of Calcium Fluoride Acceleration for Vacuum Carbothermic Reduction of Magnesia

Multisubstituted hydroxyapatite powders and coatings: The influence of the codoping on the hydroxyapatite performances

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