Aluminum Titanate (Al2TiO5) ceramics: complementary Al and Ti K-XAS studies

N. RENDTORFF; L. ANDRINI; R. MOREIRA TOJA; M.A. VIOLINI; M. GAUNA; M.S. CONCONI; F.G. REQUEJO

Campinas

Encuentro; LNLS 26th Annual Users? Meeting (RAU); 2016

LNLS

Aluminum titanate (Al2TiO5) ceramics are excellent thermal shock-resistant materials due to theirunique combination of low thermal expansion and low Young?s modulus. These are adequate forinsulating and severe thermomechanical applications [1]. Based in X-Ray and neutron diffractionstudies, Al2TiO5 was found to be one of several materials, which are isomorphous with the mineralpseudobrookite (Fe2TiO5) [2]. In this structure, each Al3+ or Ti4+ cations are surrounded by six oxygenions forming distorted oxygen octahedral. Apparently, these AlO6 or TiO6 octahedra form (0 0 1)oriented double chains weakly bonded by shared edges. This structural feature might be responsiblefor the strong thermal expansion anisotropy, which generates localized internal stresses to causesevere micro-cracking.In this study we present an Al-K XANES and a Ti-K XANES/EXAFS study of two differentaluminum titanates: one obtained from the calcination (1500 °C) of Alumina and Anatase [1], andanother from commercial powder (industrial grade). Complementary XRD - Rietveld analysis wasalso performed for long-range order studies.Spectra features obtained for the two different samples were described and compared. No importantdifferences were observed between both studied powders. In agreement with the mentionedexperimental evidence, the detected local structure consists in distorted octahedral sites in both cases.