H-bond network dynamics of the solid-state protonic conductor Rb3H(SeO4)2 from FTIR and IINS measurements

Ion conduction in proton- and related defect (super) ionic conductors: Mechanical, electronic and structure parameters

“…For mobile ion-type SICs, the B-curve is drawn with G = 10.8 and H = 0.85. SPCs and Li-ion conductors are also plotted on B-curve within a small scatter [46][47][48][49][50][51][52][53][54][55][56]. Impurity H + -ion [38,57,58] and O-ion defect conductors [5][6][7]17,59,60] are plotted on the A-curve that is drawn with G = 9.8 and H = 0.55.…”

“…4 since the compound plotted near B-or Acurve takes large or small fourth-order anharmonicity of the vibration mode and also the first-or second-order phase transition [8][9][10][11]16,27,[34][35][36][37][38][70][71][72][73][74]. Rb 3 H(SeO 4 ) 2 plotted on the position between A-and Bcurves takes the mixture of the first-and second-order phase transitions [46,47].…”

Proton Conduction Path in Rb3H(SeO4)2Studied by High Temperature Neutron Single Crystal Diffraction

“…In this direction, the distribution is broad and shallow with a small maximum at the center of the hydrogen bond. This feature well represents the large librational motion of OH, which is considered to prelude the proton conduction [11,13,23].…”

“…In the distribution, there are small bumps between the neighboring hydrogen bonds (marked by a star). As was mentioned above, the [H(SeO 4 ) 2 ] 3dimer is considered to transform into [SeO 4 ] 2and [HSeO 4 ]monomer during the proton transfer, and the concentration of the [HSeO 4 ]drastically increases above T s [23]. In the monomer state, the proton in the monomer can be temporarily at an interstitial site.…”

“…The proton conduction in the superprotonic phase is considered to be of the Grotthuss mechanism where protons are transferred through translational and rotational steps involving breaking and formation of the hydrogen bonds [21]. It has been proposed that the [H(SeO 4 ) 2 ] 3dimer temporarily has the form of [SeO 4 ] 2and [HSeO 4 ]during the transfer process [22,23], and there might be interstitial sites for protons [11]. The neutron diffraction technique has been well utilized to study ionic conductors, such as oxygen and lithium ion conductors, especially for the observation of the ionic conduction path [24].…”