Structural behavior of Tl-exchanged natrolite at high pressure depending on the composition of pressure-transmitting medium

The structural evolution of Tl-exchanged natrolite with idealized formula Tl 2 [Al 2 Si 3 O 10 ]·2H 2 O, compressed in penetrating (water:ethanol 1:1) and non-penetrating (paraffin) media, was studied up to 4 GPa. The presence of Tl + with non-bonded electron lone pairs, which can be either stereo-c...

Full description

Saved in:
Bibliographic Details
Published in:Physics and chemistry of minerals 2017-10, Vol.44 (9), p.615-626
Main Authors: Seryotkin, Yu. V., Bakakin, V. V., Likhacheva, A. Yu, Dementiev, S. N., Rashchenko, S. V.
Format: Article
Language:English
Subjects:
Cations
Coordination
Crystallography and Scattering Methods
Earth and Environmental Science
Earth Sciences
Ethanol
Geochemistry
High pressure
Mineral Resources
Mineralogy
Organic chemistry
Original Paper
Paraffins
Phase transitions
Structural behavior
Subsystems
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The structural evolution of Tl-exchanged natrolite with idealized formula Tl 2 [Al 2 Si 3 O 10 ]·2H 2 O, compressed in penetrating (water:ethanol 1:1) and non-penetrating (paraffin) media, was studied up to 4 GPa. The presence of Tl + with non-bonded electron lone pairs, which can be either stereo-chemically active or passive, determines distinctive features of the high-pressure behavior of the Tl-form. The effective volume of assemblages Tl + (O,H 2 O) n depends on the E-pairs activity: single-sided coordination correlates with smaller volumes. At ambient conditions, there are two types of Tl positions, only one of them having a nearly single-sided coordination as a characteristic of stereo-activity of the Tl + E pair. Upon the compression in paraffin, a phase transition occurs: a 5% volume contraction of flexible natrolite framework is accompanied by the conversion of all the Tl + cations into stereo-chemically active state with a single-sided coordination. This effect requires the reconstruction of all the extra-framework subsystems with the inversion of the cation and H 2 O positions. The compression in water-containing medium leads to the increase of H 2 O content up to three molecules pfu through the filling of partly vacant positions. This hinders a single-sided coordination of Tl ions and preserves the configuration of their ion-molecular subsystem. It is likely that the extra-framework subsystem is responsible for the super-structure modulation.
ISSN:0342-1791
1432-2021
DOI:10.1007/s00269-017-0887-0