Aging and non-ergodicity in superprotonic water non-stoichiometric phases of MzHy(AO(4)) ((z plus y)/2)center dot xH(2)O crystals

The evidence for the glass transitions were obtained in highly conducting d isordered phases of Cs5H3(SO4)(4) . xH(2)O (x approximate to 0.5) (PCHS), C s5H3(SeO4)(4) . xH(2)O (x < 0.4) (PCHSe) and K9H6(SO4)(8)H . xH(2)O (x < 0. 2) (NKHS) single crystals by dielectric spectroscopy, calorimetric and ultr asonic techniques. Temperatures of glass transitions T-g were found at 210, 240 and 270 K for NKHS, PCHS and PCHSe, respectively. Aging and irreversib ility of physical proper-ties were found above the glass-transition tempera ture. Both the dc- and ac-conductivity strongly depend on the history of in vestigated crystals which was changed by varying the cooling rate. Slow dyn amics is also detected on acoustic and thermal properties. The power law gi ves a good fit of time evolution of different properties at T < T-g, but ab ove T-g a long time behavior is more complicated. The role of crystalline w ater in the aging processes is discussed. (C) 1999 Elsevier Science B.V. Al l rights reserved.