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RESEARCH PRODUCT

Effect of thermal treatment on the structural evolution of 3:2 and 2:1 mullite monophasic gels

Javier AlarcónFrancisco Jose TorresFrancisco EstevanEsther Ruiz De Sola

subject

Materials scienceSpinelMineralogychemistry.chemical_elementMulliteThermal treatmentengineering.materialCondensed Matter PhysicsStructural evolutionElectronic Optical and Magnetic MaterialsChemical engineeringchemistryOctahedronAluminiumReagentMaterials ChemistryCeramics and CompositesengineeringOrthorhombic crystal system

description

Abstract Single phase mullite gels with composition 3Al2O3 · 2SiO2 (3:2) and 2Al2O3 · SiO2 (2:1) were prepared by the semialkoxide method using aluminum nitrate nonahydrate and tetraethylorthosilicate as reagents. The influence of the thermal processing conditions on the reaction sequence was investigated. Both 3:2 and 2:1 mullite gels formed orthorhombic mullite under fast heating (40 °C/min) at 900 °C. Slow heatings delayed the formation of mullite in both gel compositions but no formation of spinel was detected between 1000 °C and 1100 °C. The slow transformation of pentacoordinated aluminum to octahedral and tetrahedral arrangements probably depends on the larger size and extent of the alumina-rich inhomogeneities in gels slowly heated.

yearjournalcountryeditionlanguage
2005-05-01Journal of Non-Crystalline Solids
https://doi.org/10.1016/j.jnoncrysol.2005.02.017