AL,SI ORDERING IN CHABAZITES - A MONTE-CARLO STUDY

The Al,Si distribution in the framework of chabazites has been studied as a function of the Al loading by Monte Carlo simulations. The atom ordering has been characterized by several thermodynamic variables and order parameters obtained from the simulations at room temperature. O ne finds three different Al,Si ordering patterns, whose stability limi ts are defined from characteristic changes in the thermodynamic variab les. Long-range order is found in the atom distribution for Al loading higher than 0.44. We have found similarities with the Al,Si distribut ion in other zeolitic frameworks which include six-membered rings.