Hall Coefficient and Oxygen Stoichiometry in YBa sub 2 Cu sub 3 O sub (7-delta) Elevated Temperatures.

The Hall coefficient and resistivity of polycrystalline ceramic samples of YBa sub 2 Cu sub 3 O sub (7-delta) were measured at elevated temperatures and at various ambient O sub 2 partial pressures and correlated with separate thermogravimetric measurements of delta. In the region where the oxygen stoichiometry reaches equilibrium with external O sub 2, it is shown by isothermal plots that the Hall number density decays exponentially with increasing delta and the effective Hall mobility is weakly dependent on delta. Although transport coefficients are temperature dependent, this result lends support to the picture that oxygen doping in the cuprate acts mainly to modulate the density of hole carriers.