Rb-87 NMR spectra of hydrogen-bonded Rb3D(SO4)(2) and Rb3H(SO4)(2) crystals

Citation
A. Titze et al., Rb-87 NMR spectra of hydrogen-bonded Rb3D(SO4)(2) and Rb3H(SO4)(2) crystals, PHYS REV B, 59(18), 1999, pp. 11720-11726
Citations number
24
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
PHYSICAL REVIEW B-CONDENSED MATTER
ISSN journal
01631829 → ACNP
Volume
59
Issue
18
Year of publication
1999
Pages
11720 - 11726
Database
ISI
SICI code
0163-1829(19990501)59:18<11720:RNSOHR>2.0.ZU;2-P
Abstract
The paraelectric and antiferroelectric phases of Rb3D(SO4)(2) and Rb3H(SO4) (2) were investigated using rubidium NMR. The angle dependence of the secon d order quadrupole shifted central Rb-87 transitions was recorded at 300 K. It was found to be in full agreement with the symmetry elements of a monoc linic A2/a structure. The temperature dependence of the magnitude and asymm etry of the electrical field gradient (EFG) tensors at the Rb sites was det ermined using powder samples and revealed no differences, between protonate d and deuterated specimens. The antiferroelectric transition of Rb3D(SO4)(2 ) (T-N=82 K) is associated with a quadrupling of the unit cell. Below T-N t he magnitudes of the EFG at the Rb sites remain constant and smoothly tilt away from their high temperature orientations. The temperature dependence,o f the NMR line splittings associated with this tilt follows a power law imp lying an order parameter critical exponent of 0.21. [S0163-1829(99)07517-7] .