Issue 43, 2015

Ce0.4IIICe0.6IVAlO3.3 – an unexpected product of a solid state reaction in the CeO2–Al2O3 system

Abstract

Phase transformations in the highly dispersed CeO2–Al2O3 system subjected to heating under reducing and oxidizing atmospheres were studied by HRTEM, EDX, XRD, ICP, TPR and magnetic susceptibility measurements. It has been found that the nanocrystalline CeIIIAlO3 phase with a hexagonal structure appearing in the system during reduction in H2 at 850 °C transforms upon oxidation at 175–200 °C into a similar hexagonal phase with structural formula Ce0.4IIICe0.6IVAlO3.3. The Ce0.4IIICe0.6IVAlO3.3 phase is unstable in air above 600 °C and decomposes to nanocrystalline CeO2 and alumina. Reduction in hydrogen at 700 °C transforms the Ce0.4IIICe0.6IVAlO3.3 back to hexagonal CeIIIAlO3, which at 1000 °C (in hydrogen flow) recrystallizes into the well-known, tetragonal CeAlO3. The red–ox behaviour of the hexagonal CeAlO3 is compared with that of CeO2 and the possible implications for catalysis are discussed.

Graphical abstract: Ce0.4IIICe0.6IVAlO3.3 – an unexpected product of a solid state reaction in the CeO2–Al2O3 system

Supplementary files

Article information

Article type
Paper
Submitted
03 Aug 2015
Accepted
23 Sep 2015
First published
23 Sep 2015

CrystEngComm, 2015,17, 8282-8288

Ce0.4IIICe0.6IVAlO3.3 – an unexpected product of a solid state reaction in the CeO2–Al2O3 system

M. A. Małecka and L. Kępiński, CrystEngComm, 2015, 17, 8282 DOI: 10.1039/C5CE01549A

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