Molecular H2O in armenite, BaCa2Al6Si9O30 center dot 2H(2)O, and epididymite, Na2Be2Si6O15 center dot H2O: Heat capacity, entropy and local-bonding behavior of confined H2O in microporous

Armenite, ideal formula BaCa(2)Al(6)Si(9)O(30)center dot 2H(2)O, and its dehydrated analog BaCa(2)Al(6)Si(9)O(30) and epididymite, ideal formula Na(2)Be(2)Si(6)O(15)center dot H(2)O, and its dehydrated analog Na(2)Be(2)Si(6)O(15) were studied by low-temperature relaxation calorimetry between 5 and 300 K to determine the heat capacity, C(p), behavior of their confined H(2)O. Differential thermal analysis and thermogravimetry measurements, FTIR spectroscopy, electron microprobe analysis and powder Rietveld refinements were under-taken to characterize the phases and the local environment around the H(2)O molecule.