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https://hdl.handle.net/2142/23971
Description
Title
The chlorine ion diffusion in potassium chloride
Author(s)
Fuller, Robert Gohl
Issue Date
1965
Doctoral Committee Chair(s)
Maurer, R.J.
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
chlorine ion
ion diffusion
potassium chloride
diffusion coefficient
Harshaw single crystals
Language
en
Abstract
The diffusion coefficient of the chlorine ion in
Harshaw potassium chloride crystals and in potassium
chloride crystals containing strontium has been measured.
The measurements were made with radioactive chlorine 36 and
sectioning techniques. The chlorine ion diffusion coefficient
of the Harshaw single crystals is well represented by
D == Doexp(-W!kT) cm2/sec
from 560°C to 760°C. The value of W was found to be
2.12 + 0.05 eV and D was found to be 61 cm 2 /sec. The un-
~ , 0
certainty in the value of W produces a corresponding
uncertainty in Do from 34 cm2/sec to 110 cm2/sec.
The diffusion data for the crystals containing
strontium were not explicable on the basis of a single anion
vacancy mechanism alone. The assumption that the diffusion
of the chlorine ion occurs by a vacancy pair mechanism and
a single anion vacancy mechanism is in good agreement with
the experimental data and the diffusion parameters obtained
are in good agreement with their theoretical values. Based
on this assumption the diffusion coefficient of the chlorine
ion in KC1 is expressed as
D = Da n1.. on + D pal.. rs
The following results were obtained:
Danion = 36.51 exp(-2.l05 eV/kT) cm
2
/see
D . = 8.561 x 10 3 exp(-2.654 eV/kT) cm 2 /see. pa1.rs
This analysis also permitted the determination of the
fractional concentration of vacancies in pure KCl, no' which
was found to be
n ;: 43.91 exp{-2.313 eV!2 kT). o
The subtraction of the exponent in the no equation from the
exponent in the Danion equation gives the jump activation
energy of a single anion vacancy the value 0.948 eVe
In this analysis the low temperature data from the
regions where the log D versus 1fT curves have positive
curvature were omitted. The regions of po~itive curvature
were the Harshaw data for temperatures below 560°C and the
data from the crystal containing 469 parts per million mole
fraction strontium for temperatures below 645°C. The
possibilities of this anomalous behavior arising from dislocation
effects or impurity effects are discussed.
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