Structural Features of Oxyapatite
One of the most widely known representatives of the apatite family is hydroxyapatite, Ca<sub>10</sub>(PO<sub>4</sub>)<sub>6</sub>(OH)<sub>2</sub>. This mineral is a part of the human dental and bone tissues, and, therefore, is widely used in medicine....
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MDPI AG
2023-01-01
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| Online Access: | https://www.mdpi.com/2075-163X/13/1/102 |
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| author | Natalia V. Bulina Leon A. Avakyan Svetlana V. Makarova Igor B. Orehov Vladimir S. Bystrov |
| author_facet | Natalia V. Bulina Leon A. Avakyan Svetlana V. Makarova Igor B. Orehov Vladimir S. Bystrov |
| author_sort | Natalia V. Bulina |
| collection | DOAJ |
| description | One of the most widely known representatives of the apatite family is hydroxyapatite, Ca<sub>10</sub>(PO<sub>4</sub>)<sub>6</sub>(OH)<sub>2</sub>. This mineral is a part of the human dental and bone tissues, and, therefore, is widely used in medicine. Less known is oxyapatite, Ca<sub>10</sub>(PO<sub>4</sub>)<sub>6</sub>O, which has the same biocompatibility as hydroxyapatite. In this work, it is shown that oxyapatite can be obtained by heating hydroxyapatite powder at 1000 °C in vacuum. IR and NMR spectroscopy proved the absence of the hydroxyl groups in the apatite obtained. In the IR spectrum, the presence of new absorption bands of phosphate groups, indicating a symmetry disorder, was observed. Density functional theory modeling confirmed lowering of symmetry for the oxyapatite structure. Modeling the IR spectrum of oxyapatite made it possible to identify the experimentally observed new absorption bands. According to the modeling, the presence of a vacancy in a hydroxyl channel of the apatite structure lowered the symmetry. Powder X-ray diffraction data confirmed that full dehydroxylation of hydroxyapatite led to a decrease in symmetry to triclinic phase. Comparison of the formation energies showed that formation of the hydroxyapatite phase was more preferable than that of oxyapatite, which explains apatite’s tendency to rehydroxylation. It was shown that the solubility of oxyapatite in water was comparable to that of hydroxyapatite. |
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| format | Article |
| id | doaj.art-76b6992acc7d43e6a0c64dba79ad0554 |
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| issn | 2075-163X |
| language | English |
| last_indexed | 2024-03-09T11:37:05Z |
| publishDate | 2023-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Minerals |
| spelling | doaj.art-76b6992acc7d43e6a0c64dba79ad05542023-11-30T23:39:49ZengMDPI AGMinerals2075-163X2023-01-0113110210.3390/min13010102Structural Features of OxyapatiteNatalia V. Bulina0Leon A. Avakyan1Svetlana V. Makarova2Igor B. Orehov3Vladimir S. Bystrov4Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch of the Russian Academy of Sciences, 630128 Novosibirsk, RussiaPhysical Faculty, Southern Federal University, 344059 Rostov-on-Don, RussiaInstitute of Solid State Chemistry and Mechanochemistry, Siberian Branch of the Russian Academy of Sciences, 630128 Novosibirsk, RussiaInstitute of Solid State Chemistry and Mechanochemistry, Siberian Branch of the Russian Academy of Sciences, 630128 Novosibirsk, RussiaInstitute of Mathematical Problems of Biology, Keldysh Institute of Applied Mathematics, Russian Academy of Sciences, 142290 Pushchino, RussiaOne of the most widely known representatives of the apatite family is hydroxyapatite, Ca<sub>10</sub>(PO<sub>4</sub>)<sub>6</sub>(OH)<sub>2</sub>. This mineral is a part of the human dental and bone tissues, and, therefore, is widely used in medicine. Less known is oxyapatite, Ca<sub>10</sub>(PO<sub>4</sub>)<sub>6</sub>O, which has the same biocompatibility as hydroxyapatite. In this work, it is shown that oxyapatite can be obtained by heating hydroxyapatite powder at 1000 °C in vacuum. IR and NMR spectroscopy proved the absence of the hydroxyl groups in the apatite obtained. In the IR spectrum, the presence of new absorption bands of phosphate groups, indicating a symmetry disorder, was observed. Density functional theory modeling confirmed lowering of symmetry for the oxyapatite structure. Modeling the IR spectrum of oxyapatite made it possible to identify the experimentally observed new absorption bands. According to the modeling, the presence of a vacancy in a hydroxyl channel of the apatite structure lowered the symmetry. Powder X-ray diffraction data confirmed that full dehydroxylation of hydroxyapatite led to a decrease in symmetry to triclinic phase. Comparison of the formation energies showed that formation of the hydroxyapatite phase was more preferable than that of oxyapatite, which explains apatite’s tendency to rehydroxylation. It was shown that the solubility of oxyapatite in water was comparable to that of hydroxyapatite.https://www.mdpi.com/2075-163X/13/1/102oxyapatitecrystal structurepowder diffractionIRNMRdensity functional theory |
| spellingShingle | Natalia V. Bulina Leon A. Avakyan Svetlana V. Makarova Igor B. Orehov Vladimir S. Bystrov Structural Features of Oxyapatite Minerals oxyapatite crystal structure powder diffraction IR NMR density functional theory |
| title | Structural Features of Oxyapatite |
| title_full | Structural Features of Oxyapatite |
| title_fullStr | Structural Features of Oxyapatite |
| title_full_unstemmed | Structural Features of Oxyapatite |
| title_short | Structural Features of Oxyapatite |
| title_sort | structural features of oxyapatite |
| topic | oxyapatite crystal structure powder diffraction IR NMR density functional theory |
| url | https://www.mdpi.com/2075-163X/13/1/102 |
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