Superionic phase transitions in hydrogen bonded crystals

Плакида, Н. М.

doi:10.1002/pssb.2221350113

Cited by 15 publications

(8 citation statements)

References 10 publications

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“…[2][3][4] The roomtemperature phase ͑so-called phase II͒ is monoclinic 2 The superionic phase I above T c ϭ412 K in CsDSO 4 ͑or T c ϭ417 K in CsHSO 4 ͒ is tetragonal with the space group I4 1 /amd and aϭ5.741 Å and cϭ14.315 Å. The first-order superionic phase transition is triggered by an orientational disordering of the SO 4 tetrahedra and a resulting rearrangement of the hydrogen bond network where unfilled deuteron sites appear.…”

Section: Introductionmentioning

confidence: 99%

NMR study of deuteron interbond motion inCsDSO4

Arčon¹,

Blinc²,

Dolinšek³

et al. 1997

Phys. Rev. B

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A one-dimensional ͑1D͒ and two-dimensional ͑2D͒ NMR study of deuteron inter-H bond motion in CsDSO 4 has been performed. At room temperature we have a system of infinite zig-zag H-bonded chains which appears static on the 1D deuteron time scale. 2D exchange NMR shows the existence of inter-H-bond deuteron exchange. The temperature dependence of the deuteron spectra demonstrates that orientational disordering of the HSO 4 groups takes place as T→T c resulting in the formation of the links between previously isolated H-bonded chains and the creation of a 2D H-bonded network. From the temperature dependence of the spectra the order parameter measuring the difference in the occupation of the H bonds along the chains and perpendicular to the chains, has been determined. ͓S0163-1829͑97͒00614-0͔

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Section: Introductionmentioning

confidence: 99%

NMR study of deuteron interbond motion inCsDSO4

Arčon¹,

Blinc²,

Dolinšek³

et al. 1997

Phys. Rev. B

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“…The existence of a superprotonic transition in CsH 2 PO 4 demonstrates that solid acids, in which all the oxygen atoms are hydrogen bonded at low temperature, can exhibit such transitions. The order−disorder model that is appropriate for describing the high-temperature phase of CsHSO 4 , and presumably, also of M 3 H(XO 4 ) 2 compounds such as Rb 3 H(SeO 4 ) 2 , and which would have ruled out a transition in CsH 2 PO 4 , accordingly does not apply here. In those other materials, there is a close structural relationship between the superprotonic and ordered phases, whereas no such simple relationship appears to exist in CsH 2 PO 4 .…”

Section: Discussionmentioning

confidence: 99%

“…Cesium cations reside at sites between these layers. Plakida 10 has treated the superprotonic phase transition in the related compound, CsHSO 4 , in terms of a microscopic model that assumes an order-disorder relationship between the low-and high-temperature phases. Although not stated explicitly, such a model rules out the possibility of a superprotonic transition in a compound such as CsH 2 PO 4 , in which all oxygen atoms participate in hydrogen bond formation.…”

Section: Introductionmentioning

confidence: 99%

High-Temperature Behavior of CsH₂PO₄ under Both Ambient and High Pressure Conditions

et al. 2003

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The high-temperature behavior of CsH2PO4 has been carefully examined under both ambient and high pressure (1.0 ± 0.2 GPa) conditions. Ambient pressure experiments encompassed thermal analysis, AC impedance spectroscopy, 1H NMR spectroscopy, and polarized light microscopy. Simultaneous thermogravimetric analysis, differential scanning calorimetry, and evolved gas analysis by mass spectroscopy demonstrated that a structural transition with an enthalpy of 49.0 ± 2.5 J/g occurred at 228 ± 2 °C, just prior to thermal decomposition. The details of the decomposition pathway were highly dependent on sample surface area, however the structural transformation, a superprotonic transition, was not. Polarized light microscopy showed the high temperature phase to be optically isotropic in nature, consistent with earlier suggestions that this phase is cubic. The conductivity of CsH2PO4, as revealed by the impedance measurements, exhibited a sharp increase at the transition temperature, from 1.2 × 10-5 to 9.0 × 10-3 Ω1-cm-1, followed by a rapid decline due to dehydration. In addition, chemically adsorbed surface water was shown to increase the conductivity of polycrystalline CsH2PO4 over well-dried samples, even at mildly elevated temperatures (>200 °C). At high pressure an apparent irreversible phase transition at 150 °C and a reversible superprotonic phase transition at 260 °C were observed by impedance spectroscopy. At the superprotonic transition, the conductivity increased sharply by ∼3 orders of magnitude to 3.5 × 10-2 Ω1-cm-1 at 275 °C. This high conductivity phase was stable to the highest temperature examined, 375 °C, and exhibited reproducible and highly Arrhenius conduction behavior, with an activation energy for charge transport of 0.35 eV. Upon cooling, CsH2PO4 remained in the high-temperature phase to a temperature of 240 °C.

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“…The microscopic theory of phase transition in protonic conductors was described as correlation between short range proton and hydrogen bond [8]. It was observed that KHSO4 crystals showed a structural phase transition at 468 K [9]. It is of interest to elucidate the influence of both deuteration and dopant on the please transition temperature.…”

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confidence: 99%

“…The unit cell dimensions are a = 8. 9, b = 9.19 and c = 18.93~ Sunandana [7] detected the existence of two types of sulphate ions using electron spin resonance technique. In type I forming HSO4-dimers, which are joined through two hydrogen bonds, type II forming a polymeric chain along the a axis by means…”

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confidence: 99%

Crystal lattice dynamics and phase transitions mechanism in potassium hydro (deutrium) sulphate crystals

Kassem

1991

Journal of Thermal Analysis

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The phase transition in KHSO4 crystals of varying deutrium content and different Cu 2+ concentration is studied. The specific heat at constant pressure, Cp, and DTA measurements are investigated. The measurements are carried out in the vicinity of phase transition Tc = 468 K. Multiple ~+eaks are observed in the temperature dependence of Cp and a noticeable change due to Cu dopant. This behaviour can be attributed to the fact of order disappearance in partial melting of proton in sublattice.Among solid electrolytes, it is usual to distinguish superionic conductors, which above certain temperature Ts have anomalously high ionic conductivity. One of the most thoroughly investigated families of superionic conductor [1-4] is the group of materials represented by the general formula: (M = Na, K, Rb, Cs atom or N2H5 and NH4 group; BX4 = SO4", SeO4" or BcF4").Potassium hydrogen sulphates, KHSO4, posses orthorhombic symmetry with space group D~ and 16 molecules per unit cell [5,6]. The unit cell dimensions are a = 8. 9, b = 9.19 and c = 18.93~ Sunandana [7] detected the existence of two types of sulphate ions using electron spin resonance technique. In type I forming HSO4-dimers, which are joined through two hydrogen bonds, type II forming a polymeric chain along the a axis by means

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Superionic phase transitions in hydrogen bonded crystals

Cited by 15 publications

References 10 publications

NMR study of deuteron interbond motion inCsDSO4

NMR study of deuteron interbond motion inCsDSO4

High-Temperature Behavior of CsH₂PO₄ under Both Ambient and High Pressure Conditions

Crystal lattice dynamics and phase transitions mechanism in potassium hydro (deutrium) sulphate crystals

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Superionic phase transitions in hydrogen bonded crystals

Cited by 15 publications

References 10 publications

NMR study of deuteron interbond motion inCsDSO4

NMR study of deuteron interbond motion inCsDSO4

High-Temperature Behavior of CsH2PO4 under Both Ambient and High Pressure Conditions

Crystal lattice dynamics and phase transitions mechanism in potassium hydro (deutrium) sulphate crystals

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High-Temperature Behavior of CsH₂PO₄ under Both Ambient and High Pressure Conditions