High‐Temperature Electrical Properties of the Bi_2.1Sr_1.9(Ca_1–xY_x)Cu₂O_y Solid Solution

Abstract

By a combination of conventional physical property measurements and high-temperature electrical property studies, the solid solution limit, transport parameters, and potential defect regimes of the Bi,,Sr,,(Ca,_.Y,)Cu,O, solid solution were established. A continuous solid solution extends to x = 0.7 or 0.8. The electrical properties indicate that the product of the hole density-of-states and mobility for semiconducting compositions is approximately an order of magnitude smaller than for the other p-type superconducting cuprates. A pronounced drop in hole concentration accompanies the tetragonal-to-orthorhombic transition at x = 0.5, whereafter superconductivity disappears. The electrical properties also indicate that a composition x 2 0.7 is the appropriate "reference" compound for the solid solution series. Upon doping this yttrium-rich insulating composition with calcium, holes are introduced. With increased calcium content (decreased yttrium content) the system exhibits several defect regimes reminiscent of the behavior in the La,-,AE,CuO, (AE = Sr or Ba) system.Oxygen defects (interstitial and vacancies) are believed to play an important role in the defect structure.

Defect Analysis of Ionically Compensated Quadruple and Quintuple Perovskite Layered Cuprates with Ti Blocking Layers

“…Since thermopower and conductivity will often track with the majority electronic species according to Eqs. [5] and [6], a log conductivity}log pO or thermopower}1/¹ plot can provide useful information about the pO or temperature dependence of dominant electronic species.…”

“…[34] (5,6,28). The corresponding ln for Q"20 V/K in a Jonker measurement can be then used for a simple calculation of n , where "2n e and /I4) "Ce :…”