Thermal behavior and phase transformations of nanosized carbonate apatite (Syria)

Petkova, V.; Yaneva, V.

doi:10.1007/s10973-009-0149-6

Cited by 16 publications

(10 citation statements)

References 34 publications

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“…Similar investigations were made with natural apatite from Syria, where the SiO 2 content is much higher [5].…”

Section: Introductionsupporting

confidence: 71%

“…Consequently, the apatite from Tunisia is not a typical FAp and is CFAp-B-type or CHAp-B-type [7]. This fact is confirmed by our earlier investigations as well [3,5,10,22]. The incorporation of CO 3 2-in apatite structure changes the crystal pole of PO 4 3-groups, weakening the bonds strength of oxygen from PO 4 3-with calcium.…”

Section: Ftir Measurementssupporting

confidence: 64%

“…Using this method apatite increases the reactivity as a result of decreasing particle size and increasing structural defects due to absorption of water vapor and CO 2 (from the air) and internal redistribution of anions and cations [3][4][5][6][7]. These processes determine formation of intermediate members belonging to apatite isomorphic series.…”

Section: Introductionmentioning

confidence: 99%

“…In the literature there exist many publications concerning valuation of isomorphism in natural and synthetic apatite with spectroscopic and X-ray diffraction (XRD) methods [4] and only a couple of articles regarding to isomorphism valuation use thermal analysis [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

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Structural and thermal transformations on high energy milling of natural apatite

Petkova

Koleva

Kostova

et al. 2014

J Therm Anal Calorim

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In this work we investigated the isomorphic substitution and thermal decomposition of sedimentary fluor apatite (FAp) (with Ca/P ratio [ 1.67) from Tunisia after high-energy-milling (HEM) activation at different times from 10 to 600 min. The chemical composition of the material includes: 29.6 % P 2 O 5 total and 46.5 % CaO (main components) and 3.5 % F; 0.55 % R 2 O 3 (R = Al, Fe); 1.1 % SO 3 ; 1.9 % SiO 2 (a low content in a comparison with other natural apatites from North Africa or Asia); 0.35 % MgO; 0.05 % Cl; 6.6 % CO 2 are impurities. HEM is a well-known approach for preparing various solid materials and for increasing their reactivity. The solid-state transformation of the initial and HEM-activated apatite samples was examined by chemical analysis, BET, powder XRD, FTIR spectroscopy, and thermal analysis. The structure of natural apatite allows isomorphic substitutions of carbonate, hydroxyl, and metal ions by PO 4 3-, Ca 2? , and F -. The obtained powder XRD data indicate an increased defectiveness of the apatite structure in the course of the HEM. The solid-state transformations of the initial and HEM-activated apatite are examined by TG-DTA analyses. It is found that the thermal stability of the activated samples decreases as compared to the initial sample. This is related to the increased defectivity of the apatite structure during the high-energy milling shown by the XRD data. The thermal analysis allows the differentiation of the structurally bonded A, B, and A-B types carbonate ions from these originating from the calcite and dolomite admixtures. The results obtained demonstrate that the mechanical distortion and the structural changes related to the migration of the carbonate ions from B type to A-type channel positions are the main factors responsible for the enhanced solubility of the high-energy activated FAp.

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“…Similar investigations were made with natural apatite from Syria, where the SiO 2 content is much higher [5].…”

Section: Introductionsupporting

confidence: 71%

Section: Ftir Measurementssupporting

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structural and thermal transformations on high energy milling of natural apatite

Petkova

Koleva

Kostova

et al. 2014

J Therm Anal Calorim

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“…4) reveal reflections corresponding to CaO. The data presented give evidence that carbonate located in the tetrahedral positions of the phosphate ion in the apatite structure is liberated as CO 2 [10] and CaO was formed.…”

Section: Thermal Behavior Of Ras-dhraa Phosphoritementioning

confidence: 67%

Investigation of the structural and mineralogical changes of Tunisian phosphorite during calcinations

Elgharbi¹,

Horchani−Naifer²,

Férid³

2014

J Therm Anal Calorim

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The thermal behavior of Tunisian phosphorite was investigated with X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR), and Raman spectroscopies and DTA-TG measurements. The XRD patterns showed that the chief mineral constituents of calcined samples are calcium oxide and fluorapatite, while those in the raw phosphorite are calcite, dolomite, fluorapatite, and carbonate-fluorapatite. Physicochemical transformations result in the oxidation of organic matter, disappearance of calcite and dolomite crystalline phases, and partial dissociation of structural carbonates. The FT-IR and Raman spectra showed modifications of some bands; a decrease in the intensity of the v 2 and v 3 vibrations of carbonate groups and the appearance of new bands at 520 and 926 cm -1 after calcination of phosphorites at 800°C. These bands were assigned to isomorphous substitutions of PO 4 3-in apatite by SiO 4 4-. Heat treatment alters the qualitative composition of the mineral as a result; the solubility of apatite in dilute citric acid was decreased.

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Starch:Pectin Acidic Sachets Development for Hydroxyapatite Nanoparticles Storage to Improve Phosphorus Release

et al. 2019

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Thermal behavior and phase transformations of nanosized carbonate apatite (Syria)

Cited by 16 publications

References 34 publications

Structural and thermal transformations on high energy milling of natural apatite

Structural and thermal transformations on high energy milling of natural apatite

Investigation of the structural and mineralogical changes of Tunisian phosphorite during calcinations

Starch:Pectin Acidic Sachets Development for Hydroxyapatite Nanoparticles Storage to Improve Phosphorus Release

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