NMR and Mössbauer Study of Al₂O₃-Eu₂O₃

Abstract

Alumina-europia mixed oxides with 5 and 10 wt.% Eu₂O₃ were studied by Mössbauer spectroscopy, ²⁷Al MAS-NMR and X-ray diffraction (XRD). The samples were prepared by the sol-gel technique. The XRD patterns for the calcined samples show a broad peak around 2θ = 30° which is assigned to the Eu₂O₃; after treatment with hydrogen at 1073 K no reduction to Eu⁺² or Eu⁰ was observed. The NMR spectra show three peaks, which are assigned to the octahedral, pentahedral and tetrahedral aluminum sites; the intensity of each peak depends on the concentration of europium ions. The Mössbauer spectra of the calcined samples show a single peak near zero velocity which is attributed to the Eu⁺³; after H₂ treatment at 1073 K similar spectra were obtained, suggesting Eu⁺³ is not reducibly at this temperature.