TY - JOUR

T1 - Structural behavior of Tl-exchanged natrolite at high pressure depending on the composition of pressure-transmitting medium

AU - Seryotkin, Yu V.

AU - Bakakin, V. V.

AU - Likhacheva, A. Yu

AU - Dementiev, S. N.

AU - Rashchenko, S. V.

N1 - Publisher Copyright: © 2017, Springer-Verlag Berlin Heidelberg.

PY - 2017/10/1

Y1 - 2017/10/1

N2 - The structural evolution of Tl-exchanged natrolite with idealized formula Tl2[Al2Si3O10]·2H2O, 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,H2O)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 H2O positions. The compression in water-containing medium leads to the increase of H2O 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.

AB - The structural evolution of Tl-exchanged natrolite with idealized formula Tl2[Al2Si3O10]·2H2O, 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,H2O)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 H2O positions. The compression in water-containing medium leads to the increase of H2O 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.

KW - Crystal structure

KW - High pressure

KW - Phase transformation

KW - Pressure-induced hydration

KW - Tl-natrolite

KW - Water–cation assemblages

KW - X-ray powder diffraction

KW - Zeolites

KW - Water-cation assemblages

KW - THERMODYNAMIC PROPERTIES

KW - CRYSTAL-STRUCTURE

KW - NEUTRON-DIFFRACTION

KW - X-RAY-DIFFRACTION

KW - SINGLE-CRYSTAL

KW - POWDER DIFFRACTION

KW - PHASE-TRANSITION

KW - SUBSTITUTED NATROLITE

KW - INDUCED OVER-HYDRATION

KW - ZEOLITES

UR - http://www.scopus.com/inward/record.url?scp=85017191754&partnerID=8YFLogxK

U2 - 10.1007/s00269-017-0887-0

DO - 10.1007/s00269-017-0887-0

M3 - Article

AN - SCOPUS:85017191754

VL - 44

SP - 615

EP - 626

JO - Physics and Chemistry of Minerals

JF - Physics and Chemistry of Minerals

SN - 0342-1791

IS - 9

ER -