Standard enthalpy, entropy and Gibbs free energy of formation of «A» type carbonate phosphocalcium hydroxyapatites

Jebri, Sonia; Khattech, Ismail; Jemal, M.

doi:10.1016/j.jct.2016.10.035

Cited by 15 publications

(7 citation statements)

References 29 publications

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“…Entropy ( S , Figure A) shows very little variations by increasing pressure. The temperature trend of this thermodynamic quantity is not available in literature, and the sole possible comparison is with a single point measured at 300 K by Jebri et al, which shows that the theoretical value is slightly underestimated. As for entropy, constant volume‐ and constant pressure‐specific heat (heat capacity, Figure B) do not sensibly vary with pressure, and they start diverging at about 300 K, with C V values lower than C p ones.…”

Section: Resultsmentioning

confidence: 99%

First principle investigation of the thermomechanical properties of type A carbonated apatite

Ulian

Valdrè

2019

Int J of Quantum Chemistry

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Calcium apatites with the general chemical formula (Ca, X) 10 (PO 4 , Y) 6 Z 2 represent a mineral family of utmost importance in several fields, for example, bone biology, biomaterials, and mineralogy. However, few works have focused on the mechanical properties of these phases, and in particular, no data are available on the thermomechanical and thermodynamic properties of carbonate-bearing (hydroxyl)apatites. In the present work, the equation of state of type A carbonated apatite (CAp, Ca 10 (PO 4 ) 6 CO 3 , space group P1) was calculated by ab initio quantum mechanical methods within the density functional theory (DFT) framework. Starting from athermal results (at 0 K), the combined effect of temperature and pressure was investigated through the quasiharmonic approximation (QHA). In athermal conditions, the equation of state of the CAp unit cell volume can be described by a third-order Birch-Murnaghan formulation, with parameters V 0 = 538.14(5) Å 3 , K 0 = 106.2(7) GPa, and K 0 = 4.6(4). The QHA well described the temperature and pressure dependence of the thermodynamics and mechanical properties of the mineral. For instance, the bulk modulus at 0 GPa and ambient temperature (300 K) is K T0 = 102.95 GPa, which is lower than that of stoichiometric apatite by about 6%. The unit cell thermal expansion coefficient between 0 and 600 K was also calculated and reported. The results are in line with the few available experimental data reported in literature on type AB carbonated hydroxylapatite. The reported findings further extend the knowledge of the mechanical and thermal behaviors of this important mineral found in biological environments, results that are useful for biotechnological and other applications of the (C)OHAp phases. K E Y W O R D S bone mineralogy, carbonated apatite, DFT, Gaussian-type orbitals, quasiharmonic approximation

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Section: Resultsmentioning

confidence: 99%

First principle investigation of the thermomechanical properties of type A carbonated apatite

Ulian

Valdrè

2019

Int J of Quantum Chemistry

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“…4g) show small peaks reflections since the first week that correspond to the most intense peaks of hydroxyapatite phase (31.7 and 46.7°). After the second week, the hydroxyapatite phase is confirmed by the presence of a third peak at 75.3° [23, 27]. In addition, a peak at 57° and 66° are detected that could relate to the octacalcium phosphate and calcium carbonate crystalline phases [28, 29].…”

Section: Resultsmentioning

confidence: 99%

Effect of extrapallial protein of Mytilus californianus on the process of in vitro biomineralization of chitosan scaffolds

Jaramillo-Martínez

Vargas-Requena

Rodríguez-Gónzalez

et al. 2019

Heliyon

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Biomineralization is the process by which diverse organisms have the capacity to create heterogeneous accumulations, derived from organic and inorganic compounds that induce the process of mineral formation. An example of this can be seen an extrapallial protein (EP) of Mytilus californianus , which is responsible for carrying out the biomineralization process. In order to determine their ability to perform the biomineralization process, EP protein was absorbed and mixed in chitosan scaffolds which were tested in simulated physiological fluid. The materials were analyzed by FTIR spectroscopy, field emission scanning electron microscopy-energy-dispersive electron X-ray spectroscopy andX-ray diffraction. Results confirmed that the EP protein stimulates the rapid growth of biological apatite on the chitosan scaffolds. The mixing method favored more the apatite growth as well as the formation of second nucleation sites than the immersion method.

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“…The results are reported in Ref. [11] for calcium, [12] for strontium, and [13] for barium, together with the formation of enthalpies of the corresponding reactants. The latter were picked from the literature.…”

Section: Phosphoric Acid Industry -Problems and Solutionsmentioning

confidence: 99%

“…All of them showed the IR bands characterizing such kinds of apatites and exhibit a nonmonotonous slight variation of "c" parameter, while "a" parameter and lattice volume increase appreciably over the carbonate content. The carbonate amount was determined by C-H-N analysis (for Cabearing compounds [11]), coulometry, and Rietveld processing (for Sr compounds [12]) or thermogravimetrically (for Ba compounds [13])…”

Section: Thermochemistry Of Some A-type Carbonate Apatitesmentioning

confidence: 99%

Thermochemistry and Kinetics of the Reactions of Apatite Phosphates with Acid Solutions (II)

Jemal¹

2017

Phosphoric Acid Industry - Problems and Solutions

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The principal material in the phosphate ores is composed of calcium fluorapatite Ca 10 (PO 4 ) 6 F 2 , in which the various components have been partially substituted by magnesium, sodium, carbonate, and hydroxyl ions. These substitutions affect the stability of the material and its reactivity toward the acid attack. The present chapter reports the influence of carbonates and magnesium on these properties. Using different calorimeters, dissolution experiments of carbonated and noncarbonated Ca and Ca/Mg apatites were carried out in acid solutions leading to thermochemical quantities. The results show that substitution of carbonate for F ions in the channel (to get A-type carbonate F-apatites) results in increasing the stability of the edifice, while substitution of CO 3 for PO 4 in fluor-or hydroxyapatites (to get B-type apatites) leads to a decrease in stability. The latter phenomenon was also observed when substituting magnesium for calcium in F-apatites. The presence of the former in the apatite structure results in an increase of the speed of dissolution in acid solution that is enhanced when carbonate is also replacing phosphate groups. Dissolution mechanism of synthesized Ca/Mg F-apatites seems to be a one-step process, while dissolution of a Gafsa (TN) natural phosphate to get superphosphate fertilizer is more complex.

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Standard enthalpy, entropy and Gibbs free energy of formation of «A» type carbonate phosphocalcium hydroxyapatites

Cited by 15 publications

References 29 publications

First principle investigation of the thermomechanical properties of type A carbonated apatite

First principle investigation of the thermomechanical properties of type A carbonated apatite

Effect of extrapallial protein of Mytilus californianus on the process of in vitro biomineralization of chitosan scaffolds

Thermochemistry and Kinetics of the Reactions of Apatite Phosphates with Acid Solutions (II)

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