The effect of high pressure on the quadrupole interaction in iron-fluorine compounds
Christoe, Charles William
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/25794
Description
Title
The effect of high pressure on the quadrupole interaction in iron-fluorine compounds
Author(s)
Christoe, Charles William
Issue Date
1969
Doctoral Committee Chair(s)
Drickamer, H.G.
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
quadrupole interaction
iron-fluoride compounds
inter-atomic distance
Mossbauer spectra
compressibility
x-ray diffraction
Language
en
Abstract
Using the inter-atomic distance as a parameter, Mossbauer
spectra have been observed for the three isomorphic ferric compounds
K3FeF6, Na3
FeF6 and (NH4)3FeF6' In addition, the compressibility and
the pressure dependence of cia were determined by X-ray diffraction for
the ferrous compound FeF2 , In all of these compounds, the local
environment of the iron ion is a slightly distorted octahedron of
fluoride ions. A detailed analysis was made of the quadrupole pplitting
of the Mossbauer spectra for both the ferrous and the ferric salts.
The analysis proceeded along two lines: the usual pointcharge
approximation and a covalent approximation based upon configuration
interaction. Although the quadrupole splitting increased with pressure
in the ferric case--whereas it decreased in the ferrous case--the local
crystalline distortions were shown to decrease in both cases when the
pressure exceeded about fifty kilobars. The covalent contribution was
shown to be a significant portion of the total field gradient at the
iron sites for the ferric compounds; that is, it is of the same order
of magnitude as the gradient produced by the distorted octahedron.
For the ferrous compound, the covalent contribution was shown to be
negligible compared to the gradient produced by the ferrous valence
electron, although it did tend to diminish the latter effect. Both
the point-charge and the covalent models predict zero quadrupole
splitting in the event of a truly regular octahedral (or tetrahedral)
iron environment.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
