Computational study of tetrahedral Al–Si ordering in muscovite

摘要: The nature of Al–Si ordering across the tetrahedral sites in muscovite, K2Al4(Si6Al2O20)(OH)4, was investigated using various computational techniques. Values atomic exchange interaction parameters J l were obtained. From these parameters, a two-dimensional scheme deduced. transition temperature Tc for this is 1900 K. There are several possible schemes three dimensions, based on different stacking sequences ordered sheets sites. Monte Carlo simulations both and three-dimensional performed, but simulation only seen, implying that too slow to be attained during timescale simulation. effect interactions raise 2140 simulation, frequency occurrence 4Si0Al, 3Si1Al, 2Si2Al 1Si3Al clusters determined, which match those inferred by 29Si MAS–NMR measurements reasonably well. In fact, suggests cation seen experiments corresponds configuration with considerable short-range order no long-range order, similar state at just above an phase transition.