Resistivity and thermoelectric-power measurements of ${\mathrm{Pr}}_{\mathit{x}}$${\mathrm{Y}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Ba}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$ up to 1200 K and an electronic-structure analysis

We report measurements of absolute thermoelectric power and resistivity in ${\mathrm{Pr}}_{\mathit{x}}$${\mathrm{Y}}_{1\mathrm{-}\mathit{x}}$${\mathrm{Ba}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$, as function of x and δ, over a wide temperature range. At high temperature, the substitution of Pr for Y does not affect the thermopower and resistivity; Pr behaves then as a trivalent ion: ${\mathrm{Pr}}^{3+}$. For small x and δ the effects of substitution of Y by Pr and of oxygen deficiency on the low-temperature resistivity are additive. A simple electronic-structure model is proposed to account for thermopower as function of temperature, x, and δ.