In situ observation of electrical resistivity increase via creep-induced dislocations in n-type PbTe

A decrease in electrical conductivity is measured in situ in n-type PbTe during dislocation-climb creep deformation at 673 K. Transmission electron microscopy reveals the accumulation of high density of immobile dislocations that form stable subgrains which increase in density with increasing strain from 8 to 20%. At a constant applied stress, we conclude the increase in immobile dislocation density is primarily responsible for the continuous increase in the electrical resistivity with strain. With the assumption of constant dislocation velocity at a constant applied stress, the mobile dislocation density is a constant so the increase of immobile dislocation density with strain should dictate the total dislocation density increase during creep deformation. This effect of creep deformation on electrical conductivity, and thermoelectric properties in general, should help design materials and operational conditions to limit such adverse effects on device efficiency while engineering thermal conductivity reductions.