The effect of Zn substitution on the state of oxygen deficiency and hole concentration in Y1−xCaxBa2(Cu1−yZny)3O7−δ

We have investigated the effect of Zn substitution on the hole content, p, and the oxygen deficiency, δ, for a series of high-quality crystalline c-axis oriented thin films and polycrystalline Y1−xCaxBa2(Cu1−yZny)3O7−δ compounds over a wide range of composition (x, y, and δ). p was determined from the room-temperature thermopower, S[290 K]. When annealed at a given temperature and oxygen partial pressure, a small but systematic variation in S[290 K] was observed with Zn, for all the samples. From the analysis of the temperature derivative of resistivity, dρ/dT, at 300 K, which varies almost linearly with p, irrespective of the composition of the sample, and the thermo-gravimetric analysis (TGA), we have found that annealing under identical conditions makes the Zn-substituted compounds somewhat more oxygen deficient compared to the Zn-free ones.