NNR IN RAPIDLY ROTATED METALS By - Nottingham eTheses ...

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TABLE 6.3. DEPENDENCE OF T1 ON LATTICE PARAMETER a
SAMPLE
T1 (ms)
at 200 K
a (10-10 m) a13 (10-121 m13)
T1a -13
(10118 m-13 s)
CuC1 12.4 5.406 3.37 3.7
CuBr 31 5.691 6.58 4.7
CuI 59 6.043 14.31 4.1
although E(T*) has almost reached unity for all three halides, it
is below the point at which ionic diffusion contributes to the
overall relaxation time in any of the samples. From equation (6.1)
and with the assumption that E(T*) is the same for each halide,
the relaxation times obey the relationship
a d3v3y 202a13
1D
The velocity of sound v is given by C/d where C is the appropriate
elastic constant. Hence
Ta dlC3/2 -2e 2a 13
1yD
Although the value of d' increases by 17% from CuCl through CuBr to
CuI(87), 6p (from the values reported above) decreases by 24%.
Consequently the product d1AD remains approximately constant. The
variations of C and y over the range of cuprous halides are not
known but may reasonably be assumed to be small. In that case the
five-fold increase in T1 from CuCl to Cul must be attributed to the