SYNTHESIS OF THALLIUM-LEUCITE (TLALSI2O6) PSEUDOMORPH AFTER ANALCIME
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dc.contributor.author | Kyono A. | |
dc.contributor.author | Kimata M. | |
dc.contributor.author | Shimizu M. | |
dc.contributor.author | Saito S. | |
dc.contributor.author | Nishida N. | |
dc.contributor.author | Hatta T. | |
dc.date.accessioned | 2021-01-13T07:31:50Z | |
dc.date.available | 2021-01-13T07:31:50Z | |
dc.date.issued | 1999 | |
dc.identifier | https://elibrary.ru/item.asp?id=13979853 | |
dc.identifier.citation | Mineralogical Magazine, 1999, , 1, 75-83 | |
dc.identifier.issn | 0026-461X | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/22806 | |
dc.description.abstract | Thallium leucite, TlAlSi2O6, has been synthesized at 450°C for 7 days, under ambient conditions, by the transformation of dehydrated analcime NaAlSi2O6 in the presence of excess TlCl. This substitution of Tl for Na leads to confirmation of a thallium-leucite pseudomorph after analcime. Their optical properties, X-ray powder diffraction patterns, electron microprobe analysis, infrared spectra, and X-ray photoelectron spectroscopy have characterized the synthetic Tl-leucites. The IR spectra show that the mid-IR modes T-O stretching and T-O-T bending vibrations for TlAlSi2O6 are more resemblant of those for analcime than for leucite, KAlSi2O6. This resemblance implies that Tl cation enters the W-site rather than the S-site in the analcime structure: Na (S) + H2O (W) Û + K (leucite) Û + Tl (Tl-leucite), where represents an S-site vacancy. The mechanism of this substitution is supported by the crystal chemical constraints: inasmuch as the S-site is smaller than the W-site, Tl+ cations being larger than Na+ plainly prefer the latter site to the former. One inference from the binding energy for Tl+ by XPS is that Tl+ occupies the extra-framework site in synthetic leucite pseudomorph, rather than the smaller tetrahedral site. The difference in Al/Si disordering between analcime and leucite and the nonstoichiometry due to the solid solution of the Si3O6 component into the leucite structure may provide a fundamental insight into understanding why TlAlSi2O6 deviates from the trend defined by K-, Rb- and CsAlSi2O6 leucite series on the a-c parameter diagram, inasmuch as these three cations in the leucite structure occupy the W-sites. Finally, synthesis of TlAlSi2 O6 leucite has an implication for the existence of other polymorphs due to different degrees of Al/Si disordering, except for high- and low-temperature leucites already known: natural leucites crystallized directly through igneous processes are different from those formed by substitution of K for Na in analcimes. | |
dc.title | SYNTHESIS OF THALLIUM-LEUCITE (TLALSI2O6) PSEUDOMORPH AFTER ANALCIME | |
dc.type | Статья |
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