Structural and spectroscopic studies of mechanochemically activated nanosized apatite from Syria

Yaneva, V.; Petrov, Ognyan; Petkova, V.

doi:10.1016/j.materresbull.2008.06.004

Cited by 14 publications

(32 citation statements)

References 6 publications

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“…3, Table 1). Powder XRD measurements display that the changes in the apatite composition lead to deformations of the apatite structure along the hexagonal axis [4,14]. The deformations are related to partial substitution of PO 4 by CO 3 and F -by OH -and/or CO 3 .…”

Section: Resultsmentioning

confidence: 99%

“…Chaikina [2] has referred the apatite from Tunisia to the group of ''main apatites'' because of the Ca/P ratio, equal to 1.67. According to the same classification, in this apatite there exists isomorphic substitution of PO 4 3-by CO 3 in tetrahedral position, where the charge compensation is made by OH -(CO 3 OH) 3-? PO 4 3-or (CO 3 F) 3-?…”

Section: Ftir Measurementsmentioning

confidence: 95%

“…The object of interest are intermediate members of this series, characterized by partially isomorphic substitution of anionic (PO 4 3-, OH -, F -) and cationic (Ca 2? ) parts, forming hydroxyl-carbonate-apatite (HCAp), hydroxyl-flour-apatite (HFAp), hydroxyl-carbonate-flour-apatite (HCFAp), etc [2].…”

Section: Introductionmentioning

confidence: 99%

“…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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Section: Resultsmentioning

confidence: 99%

Section: Ftir Measurementsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%