Thermoelectric power and thermal conductivity of neutron-irradiated YBa2Cu3O7- delta.

Abstract

Thermoelectric power and thermal conductivity have been measured as a function of temperature on ceramic ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$ exposed to fast-neutron fluences of up to 6\ifmmode\times\else\texttimes\fi{}${10}^{18}$ n${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$. Irradiation causes large changes in the magnitude and temperature variation of the thermopower and, for the highest doses, results in a complete suppression of the peak in thermal conductivity that is characteristic of the nonirradiated 1:2:3 superconducting ceramics below ${T}_{c}$. The likely physical origin of the changes are the defects created in the structure by fast neutrons that drastically limit the mean-free path of phonons and the charge carriers.