Jonker “Pecir” Analysis of Oxide Superconductors

Data for the normal state of the superconducting oxide systems YBa₂Cu₃O_6+y, and the nonsuperconducting system La₃Ba₃Cu₆O_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‐xBa_xCuO₄ and Bi₂Sr₂CaCu₂O₈ scale roughly according to the density of copper ions in these materials and fall in the range 10²⁰ to 10²¹ (cm·V·s)⁻¹. Assuming DOS equal to copper content results in mobilities on the order of 0.15 cm²·V⁻¹· s⁻¹. These results are discussed in terms of possible semiconduction mechanisms.