Effect of Carbonate Content and Crystallinity on the Metastable Equilibrium Solubility Behavior of Carbonated Apatites

Baig, Arif; Fox, Jeffrey L.; Hsu, Jer; Wang, Zeren; Otsuka, Makoto; Higuchi, William I.; LeGeros, Racquel Z.

doi:10.1006/jcis.1996.0255

Cited by 69 publications

(73 citation statements)

References 8 publications

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“…5 that the MES is not simply related to the carbonate content of CAP. We have previously (27) shown, for a large number of CAPs prepared by the DCPD hydrolysis method, that CAP crystallinity was the dominant factor determining the magnitude of the MES, and, when crystallinity is taken into account, carbonate may have no further effect upon the MES. Furthermore, a recent study in our laboratory suggests that microstrain rather than crystallite size may dominate crystallinity in these CAP preparations (39).…”

Section: Resultsmentioning

confidence: 98%

“…For each plot, a smaller pIAP value corresponds to a solution with a higher degree of saturation. The fraction of CAP dissolved for a given solution then represents the fraction of CAP crystals with MESs that would be higher than that corresponding to the IAP value for that solution (25,27). As an example, a fraction of 0.54 (see dashed lines in these plots) was obtained for the 1.8% CAP equilibrated in a solution with 2.66 mM of Ca, 1.47 mM of PO 4 at the pH of 5.5 and the ionic strength of 0.50 M. The pIAPs for this same solution can be calculated as pIAP DCPD ϭ 8.0, pIAP OCP ϭ 105.75, pIAP TCP ϭ 32.7, pIAP HAP ϭ 118.0, pIAP CAP ϭ 116.9 (a CO 2 partial pressure of 2.65 ϫ 10 Ϫ4 atm was used for the atmosphere in Salt Lake City, UT), and pIAP TeCP ϭ 52.5.…”

Section: Resultsmentioning

confidence: 99%

“…Series of solutions corresponding to various levels of calcium and phosphate concentrations at a Ca/P ratio of 0.1, 1.67, or 10.0 were prepared by adding calculated amounts of CaCl 2 and NaH 2 PO 4 stock solutions to 0.1 M acetate buffer and then adjusting the pH of solution to 4.5, 5.5, or 6.5 by concentrated NaOH or HCl and the ionic strength to 0.50 M with defluoridated 4.0 M NaCl. Previously (25,27) it was shown that metastable equilibrium was generally attained in 2-8 days; thus a 2-day equilibration period was adopted for the present study.…”

Section: Buffer Solutions For the Mes Experimentsmentioning

confidence: 99%

“…The applicability of the concept of MES and MES distribution has recently been generalized to CAP preparations synthesized at different temperatures and having a range of carbonate content and crystallinities. The MES values obtained with these CAP preparations were found to correlate well with the CAP crystallinities determined by X-ray diffraction methods (27).…”

Section: Introductionmentioning

confidence: 95%

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Metastable Equilibrium Solubility Distribution of Carbonated Apatite as a Function of Solution Composition

Chhettry

Wang

Hsu

et al. 1999

Journal of Colloid and Interface Science

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Buffer Solutions For the Mes Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

See 2 more Smart Citations

Metastable Equilibrium Solubility Distribution of Carbonated Apatite as a Function of Solution Composition

Chhettry

Wang

Hsu

et al. 1999

Journal of Colloid and Interface Science

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“…O controle de tais parâmetros estruturais é importante, pois variam de acordo com a metodologia empregada na preparação da amostra 4 . Por exemplo, Baig et al 5 mostraram que a solubilidade aparente de apatitas carbonatadas apresenta forte correlação com o parâmetro de deformação Lorentziana da função de ajuste do perfil utilizada.…”

Section: Introductionunclassified

Síntese da hidroxiapatita e refinamento estrutural por difração de raios-x

Araújo¹,

Sena²,

Bastos

et al. 2007

Quím. Nova

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Recebido em 11/9/06; aceito em 27/4/07; publicado na web em 25/10/07 SYNTHESIS OF HYDROXYAPATITE AND STRUCTURAL REFINEMENT BY X-RAY DIFFRACTION. A sample of hydroxyapatite was synthesized and its crystalline structure was analyzed by X-ray diffraction by means of the Rietveld method. Two functions were used to fit the peak profiles, modified Voigt (TCHZ) and Pearson VII. The occupational factors and lattice parameters obtained by both models show that the sample does not contain relevant cationic substitutions. The interatomic distances from Ca1 to oxygens O1, O2 and O3 were adequate for a pure hydroxyapatite without defect at site Ca1. Besides, the use of multiple lines in planes (300) and (002) associated with the model Pearson VII resulted in good agreement with the TCHZ model with respect to the size-strain effects with an ellipsoidal shape of crystallites. In conclusion, the procedures adopted in the synthesis of hydroxyapatite produced a pure and crystalline material. The experimental results of transmission electron microscopy confirmed the predicted shape of crystals.Keywords: hydroxyapatite; X-ray diffraction; Rietveld method. INTRODUÇÃOOs fosfatos de cálcio sintéticos e naturais são amplamente empregados na medicina e na odontologia para a reparação de perdas de tecidos ósseos devido à sua alta compatibilidade. Dentre estes fosfatos, a hidroxiapatita Ca 10 (PO 4 ) 6 (OH) 2 -HAP possui grande importância pois é o que apresenta maior estabilidade termodinâmica próxima da temperatura ambiente 1 . Além disto, a possibilidade de revestir metais com estes fosfatos permite associar a resistência mecânica do substrato metálico com a bio-compatibilidade da hidroxiapatita. Entretanto, a hidroxiapatita permite diversas substituições atômicas durante seu processamento 2 que podem modificar seu desempenho clínico, devido às modificações quími-cas e estruturais. Assim sendo, suas diversas propriedades, tais como cristalinidade, substituição atômica (ou iônica), tamanho de cristalitos e anisotropia, precisam ser determinadas para que se assegure seu adequado comportamento in vivo No presente artigo, os alargamentos das linhas de difração de uma amostra de hidroxiapatita sintética (HAP) são analisados pelo método de refinamento de Rietveld 6 com duas funções de ajuste para o perfil da difração das linhas de reflexões com o objetivo de identificar se o procedimento de síntese foi adequado para se produzir uma hidroxiapatita pura; comparar os desempenhos destas funções por meio de seus parâmetros e de seus indicadores numé-ricos de ajuste ao padrão de difração experimental; obter informações sobre os valores dos parâmetros ocupacionais atômicos, parâmetros de rede e parâmetros posicionais para investigar possí-veis migrações catiônicas nos sítios do Ca ou aniônicas nos sítios do P e OH e obter uma visualização da forma média aparente dos cristalitos anisotrópicos no plano binário. PARTE EXPERIMENTAL MaterialUma amostra de HAP estequiométrica (razão molar Ca/P=1,67) foi produzida pela adição controlada de (NH 4 ) 2 HPO 4...

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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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Effect of Carbonate Content and Crystallinity on the Metastable Equilibrium Solubility Behavior of Carbonated Apatites

Cited by 69 publications

References 8 publications

Metastable Equilibrium Solubility Distribution of Carbonated Apatite as a Function of Solution Composition

Metastable Equilibrium Solubility Distribution of Carbonated Apatite as a Function of Solution Composition

Síntese da hidroxiapatita e refinamento estrutural por difração de raios-x

Structure and Surface Study of Hydroxyapatite‐Based Materials

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