Tinaksite and Tokkoite: X-ray Powder Diffraction, Optical, and Vibrational Properties
In this study, natural tinaksite (K<sub>2</sub>Ca<sub>2</sub>NaTi[Si<sub>7</sub>O<sub>18</sub>OH]O) and tokkoite (K<sub>2</sub>Ca<sub>4</sub>[Si<sub>7</sub>O<sub>18</sub>OH](OH,F)) collected in charoite r...
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| Format: | Article |
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MDPI AG
2022-03-01
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| Series: | Crystals |
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| Online Access: | https://www.mdpi.com/2073-4352/12/3/377 |
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| author | Ekaterina Kaneva Roman Shendrik |
| author_facet | Ekaterina Kaneva Roman Shendrik |
| author_sort | Ekaterina Kaneva |
| collection | DOAJ |
| description | In this study, natural tinaksite (K<sub>2</sub>Ca<sub>2</sub>NaTi[Si<sub>7</sub>O<sub>18</sub>OH]O) and tokkoite (K<sub>2</sub>Ca<sub>4</sub>[Si<sub>7</sub>O<sub>18</sub>OH](OH,F)) collected in charoite rocks of the Murun alkaline massif (Siberia, Russia) were examined by X-ray diffraction and optical and vibrational spectroscopic methods. A comparative analysis of the experimental diffraction patterns with respect to the calculated X-ray powder diffraction patterns was carried out for tinaksite and tokkoite powders. The shift in the diffraction peaks of tinaksite is explained by the smaller values of the unit cell parameters <i>a</i> and <i>b</i> as compared with those of tokkoite. A similar shift of the peaks is also observed in the Raman and infrared absorption spectra; however, this feature is explained by the difference in the chemical composition of the minerals. The shoulder in the absorption spectra at about 800 nm in tinaksite and 700 nm in tokkoite corresponds to the presence of Mn<sup>2+</sup> and Fe<sup>3+</sup> absorption bands, the presence of which determines the color of tinaksite and tokkoite. The luminescence band with a maximum at about 540–550 nm in the photoluminescence spectra is related to Mn<sup>2+</sup> centers, while an additional band at about 610 nm can be associated with Ti<sup>3+</sup> centers in tinaksite. The intensity of the Fe<sup>3+</sup> ESR signal increases in both samples after heating, while the intensities of the bands associated with OH groups decrease in tinaksite and tokkoite. This characteristic is the result of iron oxidation and dehydrogenation reaction. |
| first_indexed | 2024-03-09T19:58:16Z |
| format | Article |
| id | doaj.art-a986eaac0ac64174aae3c011a27c9d76 |
| institution | Directory Open Access Journal |
| issn | 2073-4352 |
| language | English |
| last_indexed | 2024-03-09T19:58:16Z |
| publishDate | 2022-03-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Crystals |
| spelling | doaj.art-a986eaac0ac64174aae3c011a27c9d762023-11-24T00:51:48ZengMDPI AGCrystals2073-43522022-03-0112337710.3390/cryst12030377Tinaksite and Tokkoite: X-ray Powder Diffraction, Optical, and Vibrational PropertiesEkaterina Kaneva0Roman Shendrik1Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, 664033 Irkutsk, RussiaVinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, 664033 Irkutsk, RussiaIn this study, natural tinaksite (K<sub>2</sub>Ca<sub>2</sub>NaTi[Si<sub>7</sub>O<sub>18</sub>OH]O) and tokkoite (K<sub>2</sub>Ca<sub>4</sub>[Si<sub>7</sub>O<sub>18</sub>OH](OH,F)) collected in charoite rocks of the Murun alkaline massif (Siberia, Russia) were examined by X-ray diffraction and optical and vibrational spectroscopic methods. A comparative analysis of the experimental diffraction patterns with respect to the calculated X-ray powder diffraction patterns was carried out for tinaksite and tokkoite powders. The shift in the diffraction peaks of tinaksite is explained by the smaller values of the unit cell parameters <i>a</i> and <i>b</i> as compared with those of tokkoite. A similar shift of the peaks is also observed in the Raman and infrared absorption spectra; however, this feature is explained by the difference in the chemical composition of the minerals. The shoulder in the absorption spectra at about 800 nm in tinaksite and 700 nm in tokkoite corresponds to the presence of Mn<sup>2+</sup> and Fe<sup>3+</sup> absorption bands, the presence of which determines the color of tinaksite and tokkoite. The luminescence band with a maximum at about 540–550 nm in the photoluminescence spectra is related to Mn<sup>2+</sup> centers, while an additional band at about 610 nm can be associated with Ti<sup>3+</sup> centers in tinaksite. The intensity of the Fe<sup>3+</sup> ESR signal increases in both samples after heating, while the intensities of the bands associated with OH groups decrease in tinaksite and tokkoite. This characteristic is the result of iron oxidation and dehydrogenation reaction.https://www.mdpi.com/2073-4352/12/3/377tinaksitetokkoiteIR spectroscopyelectron spin resonanceabsorption spectroscopythermal behavior |
| spellingShingle | Ekaterina Kaneva Roman Shendrik Tinaksite and Tokkoite: X-ray Powder Diffraction, Optical, and Vibrational Properties Crystals tinaksite tokkoite IR spectroscopy electron spin resonance absorption spectroscopy thermal behavior |
| title | Tinaksite and Tokkoite: X-ray Powder Diffraction, Optical, and Vibrational Properties |
| title_full | Tinaksite and Tokkoite: X-ray Powder Diffraction, Optical, and Vibrational Properties |
| title_fullStr | Tinaksite and Tokkoite: X-ray Powder Diffraction, Optical, and Vibrational Properties |
| title_full_unstemmed | Tinaksite and Tokkoite: X-ray Powder Diffraction, Optical, and Vibrational Properties |
| title_short | Tinaksite and Tokkoite: X-ray Powder Diffraction, Optical, and Vibrational Properties |
| title_sort | tinaksite and tokkoite x ray powder diffraction optical and vibrational properties |
| topic | tinaksite tokkoite IR spectroscopy electron spin resonance absorption spectroscopy thermal behavior |
| url | https://www.mdpi.com/2073-4352/12/3/377 |
| work_keys_str_mv | AT ekaterinakaneva tinaksiteandtokkoitexraypowderdiffractionopticalandvibrationalproperties AT romanshendrik tinaksiteandtokkoitexraypowderdiffractionopticalandvibrationalproperties |