A Mossbauer study of divalent iron in silver chloride crystals
Tumolillo, Thomas Anthony
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https://hdl.handle.net/2142/25785
Description
Title
A Mossbauer study of divalent iron in silver chloride crystals
Author(s)
Tumolillo, Thomas Anthony
Issue Date
1969
Doctoral Committee Chair(s)
Frauenfelder, Hans
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Mossbauer
divalent iron
silver chloride crystals
quadrupole relaxation rate
quadrupole splitting
Language
en
Abstract
The temperature dependence. of the quadrupole splitting and the quadrupole
relaxation rate has been investigated by means of the Mossbauer effect for
divalent iron, initially diffused as S7Co into single crystals of silver
chloride. The divalent iron ion substitutes for the monovalent silver ion
and associates with a charge compensating positive ion vacancy in a next nearest
neighbor site. The distortion of the cubic environment of the iron
ion by the vacancy produces the quadrupole splitting. The thermal motion of
the vacancy around the iron ion gives rise to random fluctuations in the
electric field gradient at the iron nucleus (quadrupole relaxation). Using a
suitable model to describe the Mossbauer line shape in the presence of
fluctuating hyperfine fields we have measured the activation energy for a
vacancy jump and obtained, E = (0.07 ± 0.02)eV.
Mossbauer measurements on single crystals of AgCl(Fe++) in magnetic
fields at 4.20K showed that the sign of the quadrupole interaction is positive.
The interpretation of the magnetic field measurements in the spin Hamiltonian
formalism also were consistent with the vacancies occupying next-nearest neighbor
sites with respect to the Fe+ + impurity.
Methods for the calculation of theoretical Mossbauer spectra in
fluctuating and static hyperfine fields are developed and used in the interpretation
of the Mossbauer measurements.
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