Structure of (ZrO2)(x)(SiO2)(1-x) xerogels (x=0.1, 0.2, 0.3 and 0.4) from FTIR, Si-29 and O-17 MAS NMR and EXAFS

A combination of Si-29 and O-17 MAS NMR, EXAFS and FTIR spectroscopy has be en used to study the atomic structure of(ZrO2)(x)(SiO2)(1-x) (x = 0.1, 0.2, 0.3 and 0.4) xerogels prepared by reacting partially hydrolysed tetraethyl orthosilicate with zirconium(rv) propoxide. Results from (ZrO2)(0.1)(SiO2) (0.9) samples reveal the oxides to be atomically mixed with no evidence of phase separation. In these samples, the nearest neighbour environment of zi rconium is similar to that found in cubic zirconia. In the (ZrO2)(0.4)(SiO2 )(0.6) samples, phase separation occurs with a significant proportion of th e zirconium present as amorphous ZrO2 with a local structure similar to tha t of monoclinic zirconia. O-17 MAS NMR and EXAFS have proven valuable techn iques for gauging the level of atomic mixing in these materials.