Crystallization of bi doped Sb₈Te₂

A rotating disc technique has been applied to measure the crystallization rate dependence of Sb8Te2 on bismuth. The laser amorphised state shows an order of magnitude increase in crystallization rate upon doping with 8 at.% bismuth. This is consistent with static measurements on as-deposited films. Ab-initio methods were used to relax a long period, Sb₂ Te₃, stacking model. The X-ray diffraction pattern was calculated from the relaxed structure and found to be consistent with experimental data; the lattice parameters of the relaxed structures were a = 4:22Å and c = 32:80Å in the case of the undoped film, a = 4:22 { 4:23Å and c = 32:78 { 33:00Å for a Bi concentration of 5.5 at. %. The calculated bulk modulus was found to increase upon doping with Bi; suggesting an increase in the crystalline viscosity. The increased crystallization rate is therefore explained in terms of either a decrease in viscosity in the amorphous phase or a reduction in the surface tension of crystalline nuclei upon doping with Bi.