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Chapter VII Reactivity at Dislocation….
Table: 7.1 The values of activation energy and pre-exponential factor for pure and amino
acid doped KDP crystals.
Sample Activation energy
kJ/mol
Pre-Exponential Factor
Pure KDP 21.95 1.96 X 10 9
KDP + 0.3 Wt.% L- histidine 19.59 2.75X10 6
KDP + 0.4 Wt.% L- histidine 20.33 5.39X10 6
KDP + 0.5 Wt.% L- histidine 19.82 3.58X10 6
KDP + 0.3 Wt.% L- threonine 18.63 1.40X10 6
KDP + 0.4 Wt.% L- threonine 18.43 1.23X10 6
KDP + 0.5 Wt.% L- threonine 18.51 1.36X10 6
KDP + 0.3 Wt.% DL-methionine 17.54 4.09X10 5
KDP + 0.4 Wt.% DL-methionine 17.21 4.48X10 5
KDP + 0.5 Wt.% DL-methionine 17.47 5.67X10 5
Table 7.1 summarizes the values of activation energy and pre-exponential
factors, calculated for pure and amino acids doped KDP crystals. The Arrhenius
plots of logarithm of average pit width W versus reciprocal of absolute
temperature T for pure KDP crystal and various weight percentage amino acids
(L-histinine, L- threonine & DL-methionine) doped KDP crystals respectively, are
shown in figures (7.4-7.6). From the slope of the plots the values of activation
energy and pre-exponential factors were calculated.
Log W
-1.0
-1.1
-1.2
-1.3
-1.4
-1.5
-1.6
Pure KDP
KDP + 0.3 Wt. % L-histidine
KDP + 0.4 Wt. % L-histidine
KDP + 0.5 Wt. % L-histidine
0.00320 0.00324 0.00328 0.00332 0.00336
Figure: 7.4 Plots of log W 1/T for pure and L-histidine doped KDP crystal.
1/T
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