Oxygen is intercalated, using a solution-based route at ambient temper
ature, into a pyrochlore oxide, thus establishing a new class of pyroc
hlore-based interstitial solid solutions: the specific system studied
is Ce2Zr2O7 and compositions in the range Ce2Zr2O7+x, 0 < x < 0.36 are
obtained; the structure of the most oxygen rich composition has been
elucidated by powder neutron diffraction.