A Positron Lifetime Study on Y1−xPrxBa2Cu3O7−δ

The temperature dependence of the positron lifetime was measured in the range from 80 to 400 K for Y1−xPrxBa2Cu3O7−δ (x = 0, 0.1, 0.3, 0.5, 0.7 and 1.0). The mean lifetime showed a clear temperature dependence for YBa2Cu3O7−δ. As Pr is doped, the temperature dependence becomes weaker systematically. There is no temperature dependence of the mean lifetime for PrBa2Cu3O7−δ. Two components can be extracted for the samples with x = 0, 0.1, 0.3 and 0.5 at lower temperatures. The long-lived lifetime is 188 ps and does not depend on either the Pr concentration or the temperature. The bulk lifetime of Y1−xPrxBa2Cu3O7−δ is 164 ps, regardless of the Pr concentration. Positron trapping effect is also discussed.