Oxygen self-diffusion in cylindrical single-crystal mullite

A mixture of SiO2 and Al2O3 was prepared from metal alkoxides and fired at 1650 degrees C to form mullite and an SiO2-rich glass phase.. After leachin g out the glass phase, crystalline mullite powder was obtained. Transmissio n electron microscopy examination revealed the powder to be cylindrical par ticles of single-crystal mullite. A diffusion experiment was performed on t he mullite to determine the oxygen diffusion coefficient. This could be exp ressed as D-oxy = 1.32 x 10(-6) exp[-397 kJ/RT] m(2) s(-1) in the range of 1100 to 1300 degrees C. This falls along the line extended through the oxyg en diffusion coefficient of forsterite, which is similar in crystal structu re to mullite. (C) 1999 The Electrochemical Society. S0013-4651(99)04-050-1 . All rights reserved.