title: Superionic phase transition in KHSO4: a temperature-dependent Raman investigation.
abstract: Temperature-dependent Raman spectroscopic studies have been carried out on KHSO4 single crystals in the temperature range 298-493 K. A structural phase transition driven by the lattice and molecular disorder is observed at 473 K. The spectral data enable an understanding of the nature of the lattice disorder across the phase transition leading to the superionic phase. The disorder in the HSO4- polymeric hydrogen-bonded chain leading to a higher symmetry in the high temperature phase is clearly captured from our Raman results. The internal S-OH and S−O stretching modes and, to a limited extent, the external modes throw light on the disorder mechanism and the enhancement of conductivity after transition.
authors.affiliation: Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064, India.
authors.forename: Diptikanta
authors.initials: D
authors.lastname: Swain
authors.forename: Venkata Srinu
authors.initials: VS
authors.lastname: Bhadram
authors.forename: Gopal K
authors.initials: GK
authors.lastname: Pradhan
authors.forename: S Venkataprasad
authors.initials: SV
authors.lastname: Bhat
authors.forename: Chandrabhas
authors.initials: C
authors.lastname: Narayana
authors.forename: C N R
authors.initials: CN
authors.lastname: Rao
mesh_terms: D044367:Phase Transition; D013059:Spectrum Analysis, Raman; D013431:Sulfates / Q000737:chemistry*; D013696:Temperature
chemical_list: D013431:Sulfates; C031512:potassium sulfate