EXAFS study of the Ti and Zr local structure in Gd2(Zr1-xTix)2O7 and (Gd1-yNdy)2(Zr1-zCez)2O7 pyrochlore matrices for nuclear waste dispos

The aim of this proposal is to perform an EXAFS experiment at the Zr and Ti K-edges on the following pyrochlore systems: a) Gd2(Zr1-xTix)2O7 solid solutions, which are promising compositions as matrices for the immobilization of actinides, and b) single and double doped (Gd1-yNdy)2(Zr1-zCez)2O7 compounds, to simulate the actinides immobilization (Nd3+ and Ce4+ are used as surrogates for incorporated Am3+ and Pu4+, respectively). This study will show any variation as a function of composition and temperature of the local order and structure of the Ti and Zr B-site octahedra, helping to rationalise the structural phase behaviour of these compounds related with their application for nuclear waste disposal.