Preparation of Al2TiO5-ZrO2 mixed powders via sol-gel process - Code: DP7

Abstract

Sol-gel routes in the ternary system Al2O3-TiO5-ZrO2 were investigated to prepare Al2TiO5-ZrO2 mixed powders. The preparation of ZrTiO4 and Al2TiO5 was studied before going on with the ternary system. Zirconium titanate precursor gels were prepared from Ti(OPri)4 and Zr(OPrn)4 mixtures. The crystallization of ZrTiO4 develops at T<700°C. Al2TiO5 was prepared by different ways, using mixtures of Al(OBus)2(C6H9O3) with Ti(OPri)4 (i), or with acetic acid addition (ii). Route (i) leads to a separate crystallization of TiO2 and α-Al2O3, with subsequent formation of β-Al2TiO5 at T≈1360°C. Although the pseudobrookite β-Al2TiO5 is thermodynamically unstable below 1280°C, route (ii) leads to the crystallization of metastable β-Al2TiO5 at T≈800°C. At increasing temperature, β-Al2TiO5 decomposes into TiO2 and α-Al2O3, then the two compounds react to form stable β-Al2TiO5. For the ternary system, all the preparation routes which were studied lead to ZrTiO4 and α-Al2O3 with subsequent reaction (at T≈1500°C) to give β-Al2TiO5 and ZrO2. © 1994 Kluwer Academic Publishers.