The self-diffusion of Cd in CdS

The self-diffusivity of Cd in CdS, D(Cd), has been measured by a radiotracer technique between 500 and 850 degrees C at the minimum total pressure (p Cd min ) and saturated Cd pressure (p Cd sat ) and also as a function of p Cd at 675, 750 and 850 degrees C. Above 700 degrees C D(Cd, p Cd sat )=(0.058/sub // * 1.44)exp(-(1.85+or-0.03) eV/kT) cm 2 s -1 and D(Cd, p Cd min )=(1.53/sub // * 3.17) exp(-(2.47+or-0.11)eV/kT) cm 2 s -1 , whereas below 700 degrees C D(Cd,p Cd sat )=(672/sub // * 16.3) exp(-(2.67+or-0.22) eV/kT) cm 2 s -1 and D(Cd, p Cd min )=(7.6+or-2.8)*10 -14 cm 2 s -1 . Above 700 degrees C the results are satisfactorily explained in terms of a Cd i .. or a doubly ionised Cd i -related donor and a (Cd i x Cd i . )pair or a Cd s defect diffusion mechanism. Below 700 degrees C the situation is much less clear although there are indications of a V Cd or V Cd -related mechanism.