Local chemistry and vibrational behavior of the rare-earth in the high Tc superconductor EuBa2Cu3O7−□

Temperature dependent 151Eu Mossbauer spectroscopy experiments on the high Tc≧90K superconductor EuBa2Cu3O7 in the range of 4.2K < T < 300K display evidence of Eu3+ site only. No evidence of Eu2+ sites is observed. Variation of isomer-shift σ(T) and recoil-free-fraction f(T) shows that the mean square displacement (lnf) and mean square velocity (σ) of the Eu3+ site are both characterized by a Debye temperature θD=280(5)K. No discernible evidence of a phonon mediated structural transition as a precursor to Tc is observed in the temperature range examined.