Polarized Raman spectra of Cs5H3(SO4)4· H2O single crystals

Abstract

The Raman spectra of the superprotonic conductor Cs,H,(S0,),.H20 have been investigated in the 300-500 K range. An assignment of bands due to internal and external vibrations in term of approximate type of motions is proposed. The spectroscopic results are used for discussing crystal structures of different phases, the type of structural disorder and phase transitions.

Evidence for a Quasi-Two-Dimensional Proton Glass State inCs5H3(SO4Lushnikov1, Gvasaliya2, Fedoseev3 et al. 2001Phys. Rev. Lett.Self Cite5000View full textAdd to dashboardCite

“…A pronounced increase in damping of basal plane phonons sets in near 320 K, while the onset of similar behavior for the phonons with q ph k C 6 does not occur until 350 K. Above 360 K, we could not detect the Brillouin component in the light scattering spectra. A similar behavior was observed in Raman scattering experiments, where the background and quasielastic scattering contribution increased sharply in the vicinity of T 360 K [9], indicating significant changes in the light scattering conditions in the crystal (formation of cracks, inhomogeneities, etc.). In Ref.…”

“…At room temperature, the PCHS crystals belong to the hexagonal system with space group P6 3 ͞mmc (a 6.2455 Å, c 29.690 Å; V 1003 Å 3 ; Z 2) [7]. Events of particular interest occur in the vicinity of T c1 414 K and T c2 360 K. At T c1 , a superprotonic phase transition is accompanied by a symmetry change P6͞mmm , P6 3 ͞mmc [7,8], and at T c2 an isostructural phase transition takes place, associated with changes in the local symmetry of SO 4 tetrahedra [9][10][11]. No other anomalies associated with structural changes in protonic samples were observed.…”

Studies of structure, thermal, and electrical properties for Cs 5 H 3 (SO 4 ) 4 crystal

“…On the other hand, the Cs 5 H 3 (SO 4 ) 4 ·xH 2 O crystal undergoes two successive phase transitions, which the symmetry changes from hexagonal (space group P6 3 /mmc, phase II) to hexagonal (space group P6/mmm, phase I) at 414 K, and a glass-like state is realized at below 260 K [8][9][10][11][12][13]. But the structure of this crystal in phase I has not been determined yet.…”

Brillouin light scattering anomalies and new phase transition in Cs5H3(SO4)4 crystals

“…The properties of PCTS crystals have been widely studied. For instance, their structure was analyzed by X-ray diffraction [1,3], the conductivity mechanism was studied by dielectric measurements [1,4], neutron scattering [5] and NMR spectroscopy [6], and the vibration spectrum was investigated by IR, Raman, Brillouin and neutron scattering in a wide temperature range [7][8][9][10]. Nevertheless, the sequence of phase transitions is still unclear.…”