Jonker “Pecir” Analysis of Oxide Superconductors

Data for the normal state of the superconducting oxide systems YBa 2 Cu 3 O 6+y , and the nonsuperconducting system La 3 Ba 3 Cu 6 O 12.5+y , when plotted as thermoelectric coefficient versus logarithm of conductivity, exhibit Jonker “pear” behavior, confirming the semiconducting character of these materials. The symmetry of the plots indicates similar conduction parameters (density‐of‐states (DOS), transport constants, and mobilities) for p ‐ and n ‐type mechanisms. Band gaps on the order of 0.5 eV are obtained. DOS—mobility products for the above‐mentioned systems and La 2‐x Ba x CuO 4 and Bi 2 Sr 2 CaCu 2 O 8 scale roughly according to the density of copper ions in these materials and fall in the range 10 20 to 10 21 (cm·V·s) −1 . Assuming DOS equal to copper content results in mobilities on the order of 0.15 cm 2 ·V −1 · s −1 . These results are discussed in terms of possible semiconduction mechanisms.