Sol-gel synthesis of tunable cerium titanate materials

Abstract

Cerium titanate structures present a high technological interest because of their optical and catalytic properties. This work reports the synthesis of these materials by a sol-gel methodology which allows to obtain mixed oxides with Ti(IV)/Ce(III), Ti(IV)/Ce(IV) or Ti(IV)/Ce(III)-Ce(IV) species. Crystallization of CeO2-TiO2 mixed oxides and Ce2Ti2O7 pyrochlore phase has been corroborated by XRD and Raman spectroscopy. Magnetic and EPR measurements have been performed in order to clarify the oxidation state of cerium ions in the system, due to the easy oxidation of Ce(III). The firing atmosphere is crucial for the Ce(III)/Ce(IV) ratio which is responsible for the different structure, also affecting to the coloration (yellow, green, brown). This methodology offers the possibility to modulate the Ce3+/Ce4+ content and particle sizes providing more ecological coloured pigments based on rare earth elements which could be interesting materials for advanced applications in catalysis