Atomistic simulations on mullite Al2(Al2+2xSi2−2x)O10−x in a variable range of composition

Two structural models representative of the average structure of mullite Al2(Al2+2xSi2−2x)O10−x□x have been developed. The models have been used to perform a quantum mechanical (ab initio) calculation with the Castep program (Accelrys®) in order to evaluate the internal energy of mullite with a compositional range of x = 0.25–0.492. In addition, the real sillimanite structure (x = 0) has been compared with the computational results.