Apatite Thermochemistry: The Simple Salt Approximation

Glasser, Leslie

doi:10.1021/acs.inorgchem.9b02343

Cited by 10 publications

(1 citation statement)

References 29 publications

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“…This latter permitted one to estimate the standard formation enthalpy H°f, entropy S° and Gibbs free energy Gf° of phosphate apatites based on their chemical composition [231] (Table 2), with a relative uncertainty of the order of 0.5-1%. This approach was cross-validated on the basis of the Simple Salt Approximation (SSA) [232]. Lately, the Therm'AP model has also been extended to additional metal cations [233] (namely Ni 2+ , Co 2+ , Mn 2+ and Fe 2+ ) that may also be relevant to the field of catalysis.…”

Section: Overview Of Apatites Thermodynamicsmentioning

confidence: 99%

Structure and Surface Study of Hydroxyapatite‐Based Materials

Costentin

Drouet

Salles

et al. 2022

Design and Applications of Hydroxyapatite‐Based Catalysts

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In addition to designing catalytic materials ever more active and selective, the emergence of new classes of greener catalysts remains very challenging. The apatite family system with hydroxyapatite (HA) structure appears as a good candidate for catalysis due to its ecocompatibility properties, its sorption ability toward organic molecules, and its tunable composition resulting into modulation of its surface properties. Depending on their mode of preparation, these inexpensive and environment-friendly apatitic calcium phosphates exhibit properties of relevance to catalysis, such as large surface area and various morphologies.However, most studies focused so far on the catalytic performance of these compounds, while the study of structure-reactivity relationships required for rationalized optimization remains rather limited. This chapter aims at providing tools to help understand the catalytic behavior of apatite compounds, giving details about their structure, surface properties, and reactivity; this will include both stoichiometric and nonstoichiometric compounds, sometimes biomimetic and potentially substituted. A special attention is dedicated to recent advances in the characterization of their structural properties (bulk and surface/interphase) that have a strong impact on their reactivity, through both experimental and computational approaches to study the mechanisms occurring in the structure or at the crystals surface, as well as thermodynamic and dynamical properties. Remaining characterization challenges for apatite-based catalysts will also be discussed. 1.an influence on the charges carried by the cation and on the related strength of the Ca-O interaction [127], which results in different adsorption properties with guest molecules. To go further, quantum calculations coupled with NMR (Nuclear Magnetic Resonance) resultsshowed the impact of the presence of OHions on the migration of Ca 2+ as well as the rotation of PO4 3groups [128]. In the hydroxyapatite structure, phosphate ions PO4 3are the largest components of the structure. As such, they provide a primary backbone via 3D compact-like piling, generating interstitial sites for the other ions of the structure. Metal cations such as Ca 2+ occupy two types of crystallographic sites, denoted Ca1 (4 sites per unit formula) and Ca2 (6 sites per unit formula), see Figure 2. Ca1 sites are localized along the trigonal axis with the coordinates (1/4, 3/4, 1/2) and (3/4, 1/4, 1/2), forming linear columns along the c-axis. Ca2 sites in contrast form equilateral triangles at z = 1/4 and z = 3/4 on the sixfold screw (senary) 63 axes. Adjacent Ca1 and Ca2 sites are linked through shared oxygen atoms from PO4 tetrahedra. Ca1 sites generate (distorted) polyhedra where the metal ion is in ninefold coordination, while in Ca2 sites it is in sevenfold coordination.The Ca2 triangles contribute to delimit so-called "apatitic channels" where ions such as OHare axially located (Figure 3) [116,120]. In calcium hydroxyapatite, the Ca2 triangular sites correspond to the narrow...

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Section: Overview Of Apatites Thermodynamicsmentioning

confidence: 99%

Structure and Surface Study of Hydroxyapatite‐Based Materials

Costentin

Drouet

Salles

et al. 2022

Design and Applications of Hydroxyapatite‐Based Catalysts

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The prediction method for standard enthalpies of apatites using the molar volume, lattice energy, and linear correlations from existing experimental data

Puzio

Manecki

2022

Contrib Mineral Petrol

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Experimental data of thermodynamic state functions and molar volume for phosphate, arsenate, and vanadate apatites containing Ca, Sr, Ba, Pb, end Cd at the cationic positions Me2+ and F, OH, Cl, Br, and I at the halide position X were collected. The apatite supergroup splits into distinct subgroups (populations) constituted by Me10(AO4)6X2 with the same Me2+ cations and tetrahedral AO43− anions but with different anions at the X position. Linear relationships between various parameters within apatite subgroups are observed. The prediction method for standard enthalpies of apatites (ΔHºf,el) is based on regression analysis of the linear correlations within the subgroups between ΔH°f,el of apatites and their molar volume Vm, lattice energy UPOT, and ΔH°f,el of their anions AO43− or X−. This allowed to predict 22 new ΔH°f,el values for apatites and materials with an apatite structure. The prediction precision is comparable to the experimental uncertainty obtained when reproducing experimental data using calorimetric measurements or dissolution experiments and can be applied to a wider range of apatites than other methods.

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Estimation of missing third-law standard entropy of apatite supergroup minerals using the optimized Volume-based Thermodynamics

Puzio,

Manecki

2024

Contrib Mineral Petrol

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The thermodynamic characterization of apatite minerals, critical for understanding geological processes and material applications, faces significant challenges due to the scarcity of experimental data, particularly standard entropy (S°) values. In this study, we address this gap by optimization of predictive method based on Volume-based Thermodynamics. In the proposed method, the optimization of the widely used Volume-based Thermodynamics is based on breaking down a single linear functional relationship of formula unit volume (Vm) with S° into a set of linear equations. The apatite supergroup splits into distinct subgroups (populations) formed by Me10(AO4)6X2 with the same Me2+ cations and tetrahedral AO43− anions but with different anions at the X position. Our approach leverages empirical correlations between Vm and S° within specific apatite subgroups. By analyzing the correlations within the subgroups, we established the system of precise linear relationships between S° and Vm, facilitating accurate S° predictions for a wide range of apatite compositions. The proposed approach represents a significant advancement over existing predictive methods offering unparalleled accuracy in estimating S° values for apatite minerals. Through rigorous regression analysis and validation against experimental data, we demonstrate the reliability and robustness of our predictive model across various apatite subgroups. Our findings provide crucial thermodynamic data for understudied apatite compositions and shed light on fundamental relationships between crystal structure and thermodynamic properties in apatite minerals. The precise estimation of S° values enables more accurate modeling of phase equilibria, reaction kinetics, and geological processes involving apatite minerals, facilitating advancements in diverse fields ranging from environmental geochemistry to material science.

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Apatite Thermochemistry: The Simple Salt Approximation

Cited by 10 publications

References 29 publications

Structure and Surface Study of Hydroxyapatite‐Based Materials

Structure and Surface Study of Hydroxyapatite‐Based Materials

The prediction method for standard enthalpies of apatites using the molar volume, lattice energy, and linear correlations from existing experimental data

Estimation of missing third-law standard entropy of apatite supergroup minerals using the optimized Volume-based Thermodynamics

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