X-Ray diffraction study of oxygen deficient Y$_2$Ti$_2$O$_{7-\delta}$ pyrochlore powders synthesized by high-energy ball milling (HEBM)

Guillaume Josserand (1) , Laurent Chaffron (1) , Joel Ribis (2) , Pierre-Francois Giroux (1) , Thierry Gloriant (3) , David Simeone (2)

1 LTMEx - Laboratoire des Technologies des Matériaux EXtrêmes
2 LA2M - Laboratoire d'Analyse Microstructurale des Matériaux
3 ISCR - Institut des Sciences Chimiques de Rennes

Y$_2$Ti$_2$O$_7$ pyrochlore are widely used for various applications, from oxygen transport to materials strengthening. Ultra-pure oxygen deficient Y$_2$Ti$_2$O$_{7-\delta}$ pyrochlore powders synthesized by high-energy ball milling (HEBM) are studied by X-ray diffraction (XRD). Rietveld analysis of diffraction patterns reveals that a large oxygen sub-stoichiometry can be accommodated in this material with only minor structural changes. This accommodation results from the ability of Ti ions to change their valence state, which is confirmed by complementary EELS analysis. It may also explain why Y$_2$Ti$_2$O$_7$ is both radiation and mechanical milling resistant. This work highlights the fact that selection of cations allows rigid ionic structures like pyrochlore to accommodate a large amount of point defects.

Keywords: Oxygen-deficient pyrochlore; X-ray diffraction; Defective ionic structure

Domains: Material chemistry

Guillaume Josserand, Laurent Chaffron, Joel Ribis, Pierre-Francois Giroux, Thierry Gloriant, et al.. X-Ray diffraction study of oxygen deficient Y$_2$Ti$_2$O$_{7-\delta}$ pyrochlore powders synthesized by high-energy ball milling (HEBM). Journal of Solid State Chemistry, 2022, 315, pp.123446. ⟨10.1016/j.jssc.2022.123446⟩. ⟨cea-03773105⟩