Defect formation in the intermediate layers of YBa2Cu3O7-d superconductors depending on oxygen сontents
Анотація
In YBa2Cu3O7-d superconductors with 0≤δ<0.6 the defect formation in the intermediate layers depending on oxygen content was revealed under γ-irradiation with doses 8-250 kGy. In YBa2Cu3O7 the subthreshold creation of Ba, Cu1, O1 defects, which give rise to lowering of the annihilation rate of positrons and lattice parameter c, disorder of Cu-O chains, dominates. The defect formation is weakened with δ growth. In YBa2Cu3O6.7 superconductor the subthreshold pushing out of atoms occurs at low temperatures and in O1→O5 transitions, while in compounds with δ>0.3 the subthreshold defect formation in the intermediate layers is not observed. The subthreshold defect formation is related to the Coulomb ejection of atoms from the lattice sites in the field of the weakly damped low‑frequency collective excitations enhanced by irradiation in YBa2Cu3O7-d superconductors with δ≤0.3.
Посилання
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