Browsing by Author "Yakushkin, E. D."

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Influence of NH4-Rb substitution on the phase transitions with different kinds of proton disorder in mixed [(NH4)1-xRbx]3H(SO4)2 crystals
(1998-09) Baranov, A. I.; Dolbinina, V. V.; Yakushkin, E. D.; Vinnichenko, Yu. V.; Schmidt, V. Hugo; Lanceros-Mendez, S.
The role of ammonium ions in order–disorder ferroelastic, ferroelectric and structural phase transitions was studied in mixed [(NH4)1–x Rb x ]3H(SO4)2 0 < x < 1 crystals by dielectric spectroscopy and ac calorimetry. A new superprotonic phase was detected in compounds with x > 0·6. It was found that small Rb concentrations, x < 0·05, strongly smear out the temperature anomalies of dielectric constant and specific heat for phase transitions II–III, III–IV, IV–V and V–VIII. At x > 0·09 these phase transitions are fully suppressed. Finally, for Rb concentrations 0·05 < x < 0·9 a proton glass phase appears below 35 K.