Data for the normal state of the superconducting oxide systems YBa2Cu306+, and E U B~~C U~O~+~, and the nonsuperconducting system L~~B~~C U~O I Z .~+~, 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 La2-,BaXCuO4 and BiZSrZCaCu208 scale roughly according to the density of copper ions in these materials and fall in the range 10'' to 10" (cm -V -s)-'. Assuming DOS equal to copper content results in mobilities on the order of 0.15 cm*.V-'*s-'. These results are discussed in terms of possible semiconduction mechanisms.[

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High-temperature (650" to SSOOC) electrical conductivity and Seebeck coefficient measurements as functions of oxygen partial pressure and temperature in polycrystalline lanthanum cuprate support a defect model consisting of oxygen interstitials charge compensated by electron holes. The La : Cu ratio was therefore estimated to be 2.000 ? 0.001. By comparison with existing oxygen nonstoichiometry data, the high-temperature electron hole mobility and density-ofstates were estimated. [

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