Fundamental aspects of Am and Cm In Zirconia-based materials: investigations using X-ray diffraction and Raman spectroscopy

Abstract

We have investigated incorporation of americium and curium in selected zirconia-based materials. Fundamental aspects were explored via X-ray diffraction and Raman spectroscopy. First explored was the pseudo ternary system, AmO2-ZrO2-Y2O3. It was found that stable, cubic solid solutions (AmxZrl-x.Yy)O2-2/y can be obtained for selected compositions. The cell parameters of the cubic phases were established as being linear with the AmO2 content. For the Cm2O3-ZrO2 system, it was determined that diphasic materials are produced, except for two compositions: 25mol% and 50 mol% of CmO1,5. For these compositions a single-phase cubic fluorite type solid solution (a=5.2lÅ ±0.01) and a pyrochlore oxide Cm2Zr2O7 (a=10.63 Å ±0.02) are formed, respectively. The stability of pyrochlore oxides is also being investigated as a function of self-irradiation, using shorter-lived isotopes, one being the californium pyrochlore 249Cf2Zr2O7. We obtained evidence that after six months of storage the pyrochlore oxide is undergoing structural changes. Additional studies are in progress.