Normal state conduction in Gd(Ba<Subscript>2–x</Subscript>Pr<Subscript>x</Subscript>)Cu<Subscript>3</Subscript>O<Subscript> <Emphasis Type="Bold">7+δ </Subscript>
The normal state resistivity of single phase polycrystalline Gd(Ba<Subscript>2–x </Subscript>Pr<Subscript> x </Subscript>)Cu<Subscript>3</Subscript>O<Subscript>7+δ</Subscript> samples with 0.0≤x≤0.50 have been investigated. There is a distinct metal-insulator transition at <InlineEquation ID="IEq1"> <EquationSource Format="MATHTYPE">% MathType!MTEF!2!1!+- % feaafaart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiEamaaDa % aaleaacaWGJbaabaGaaeytaiaabMeacaqGubaaaOGaeyypa0JaaGim % aiaac6cacaaIYaaaaa!3DA8! </EquationSource> <EquationSource Format="TEX">$$ x_c^{{\rm{MIT}}} =0.2 $$ </EquationSource> </InlineEquation>and a superconductor-insulator transition at <InlineEquation ID="IEq2"> <EquationSource Format="MATHTYPE">% MathType!MTEF!2!1!+- % feaafaart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamiEamaaDa % aaleaacaWGJbaabaGaae4uaiaabMeacaqGubaaaOGaeyypa0JaaGim % aiaac6cacaaIZaGaaGynaaaa!3E6E! </EquationSource> <EquationSource Format="TEX">$$ x_c^{{\rm{SIT}}} =0.35 $$ </EquationSource> </InlineEquation>with the increase of x. The two-dimensional variable range hopping is dominant in the normal state resistivity of the samples. The localization length, hopping range, and hopping energy of carriers show that Pr doping strongly localizes the carriers in normal state, and finally causes the suppression of superconductivity. Copyright EDP Sciences, Springer-Verlag 2003
