English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

In this study, natural tinaksite (K2Ca2NaTi[Si7O18OH]O) and tokkoite (K2Ca4[Si7O18OH](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 a and b 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 Mn2+ and Fe3+ 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 Mn2+ centers, while an additional band at about 610 nm can be associated with Ti3+ centers in tinaksite. The intensity of the Fe3+ 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.

Tinaksite and Tokkoite: X-ray Powder Diffraction, Optical, and Vibrational Properties