Rb5H7(PO4)4 as a New Example of the Superprotonic Conductor
Статья (Full article),
, E-ISSN: 1862-0760
||Ac-impedance spectroscopy; Proton conductivity; Rb 5 H 7 (PO 4 ) 4; Superprotonic conductors; Thermal analysis
Gaydamaka Anna A.
Ponomareva Valentina G.
Bagryantseva Irina N.
Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch of the Russian Academy of Sciences
Novosibirsk State University
Thermal and transport properties, as well as spectral characteristics of Rb5H7(PO4)4, have been investigated by several methods. It was shown that Rb5H7(PO4)4 undergoes a reversible phase transition at Tp ~ 237 °С. However, the interval of the high-temperature phase stability is quite narrow, about 15 °С. The initial dehydration event in Rb5H7(PO4)4 occurs at 200 °С. The conductivity measurements were performed under highly humidified conditions (PH2O ≈ 0.56 atm.) to suppress dehydration of the title salt. The phase transition leads to the sharp increase of proton conductivity up to 10−2 S/cm. The reverse transition goes slowly with significant hysteresis on cooling. Thus, the superprotonic conductivity of Rb5H7(PO4)4 was determined. The possibility of superionic phase stabilization by humidification was shown. The IR- and Raman spectra have been recorded at room temperature and discussed in relation to the crystal structure.