Electron and phonon scattering Thermoelectricity in potassium and alloys at very low temperatures

An experimental study has been made at very low temperatures of the thermoelectric power of potassium and alloys with sodium, rubidium and caesium as solutes. The results enable a clear separation to be made between the ‘ electron diffusion ’and‘ phonon drag' components of thermoelectric power. Comparison of the results with theory has led to a number of useful conclusions about phonon and electron scattering in potassium; we believe our results also confirm that the Fermi surface in pure potassium must be nearly spherical and we have drawn conclusions about the influence of rubidium and caesium in distorting the Fermi surface of potassium. Our interpretation of the data on phonon scattering by impurities has led us to consider the possible role of coherent scattering of lattice waves when the impurity concentration becomes fairly high. It appears that of the three impurities, rubidium probably strains the parent lattice least when it is present in solid solution.