Model for proton conductivity in phase III of (NH4)3H(SeO4)2 along the c-axis

Masłowski, Tomasz; Zdanowska-Fra̧czek, M.; Lindner, Łukasz

doi:10.1016/j.ssi.2017.02.015

Cited by 8 publications

(5 citation statements)

References 35 publications

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“…It is the reason for the reduction of the actual (average) height of the potential barrier for proton movement and, in consequence, to an increase in conductivity. Such a distortion occurring close to the phase boundary was confirmed by a one-dimensional numerical model of proton diffusion simulated by means of the kinetic Monte Carlo method (Masłowski et al, 2017).…”

Section: Figurementioning

confidence: 69%

A closer look at superionic phase transition in (NH₄)₄H₂(SeO₄)₃: impedance spectroscopy under pressure

Lindner

Zdanowska-Fra̧czek

Czapla

et al. 2020

Acta Crystallogr Sect B

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The proton-conducting material (NH 4 ) 4 H 2 (SeO 4 ) 3 is examined to check whether its conductivity spectra are sensitive to subtle changes in the crystal structure and proton dynamics caused by external pressure. The AC conductivity was measured using impedance spectroscopy, in the frequency range from 100 Hz to 1 MHz, at temperatures 260 K < T < 400 K and pressures 0.1 MPa < p < 500 MPa. On the basis of the impedance spectra, carefully analyzed at different thermodynamic conditions, the p-T phase diagram of the crystal is constructed. It is found to be linear in the pressure range of the experiment, with the pressure coefficient value dT s /dp = À0.023 K MPa À1 . The hydrostatic pressure effect on proton conductivity is also presented and discussed. Measurements of the electrical conductivity versus time were performed at a selected temperature T = 352.3 K and at pressures 0.1 MPa < p < 360 MPa. At fixed thermodynamic conditions (p = 302 MPa, T = 352.3 K), the sluggish solid-solid transformation from low conducting to superionic phase was induced. It is established that the kinetics of this transformation can be described by the Avrami model with an effective Avrami index value of about 4, which corresponds to the classical value associated with the homogeneous nucleation and three-dimensional growth of a new phase.

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Section: Figurementioning

confidence: 69%

A closer look at superionic phase transition in (NH₄)₄H₂(SeO₄)₃: impedance spectroscopy under pressure

Lindner

Zdanowska-Fra̧czek

Czapla

et al. 2020

Acta Crystallogr Sect B

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“…It is worth noting that the change in the electric properties of the TeAHSe crystals from poor conductor to superionic one is a result of a weakening of the N–H···O subnetwork created by NH 4 + cations. These N–H···O bonds are long, weak, and unstable even at room temperature, so NH 4 + and SeO 4 – orientational disorder at high temperatures leads to these bonds’ elongation , and, in consequence, to the diffusion of ammonium cations.…”

Section: Results and Discussionmentioning

confidence: 99%

“…Therefore, the ammonia cations diffusion in the TeAHSe bulk should be very well visible in the temperature dependence of the 1 H NMR absorption signal moments ratio M 4 /M 2 2 . Figure 6 − orientational disorder at high temperatures leads to these bonds' elongation 19,20 and, in consequence, to the diffusion of ammonium cations.…”

Section: Resultsmentioning

confidence: 99%

“…These results indicate that the change in electrical properties of the (NH 4 ) 4 H 2 (SeO 4 ) 3 crystal from an insulator to a superionic conductor is closely related to the dynamic processes taking place in the subnetwork of H-bonds created by NH 4 cations. The effective shape of the H-bond potential, which is the main factor responsible for the proton diffusion, comes from the interplay of the H-bond length and the amplitude of lattice vibrations and may not be limited to a static situation. , The N–H···O bonds are long, and the subnetwork they form is weak. Even a small change in temperature may significantly change the H-bond potential which trapped protons and NH 4 ions.…”

Section: Discussionmentioning

confidence: 99%

“…The effective shape of the H-bond potential, which is the main factor responsible for the proton diffusion, comes from the interplay of the H-bond length and the amplitude of lattice vibrations and may not be limited to a static situation. 19,20 The N−H•••O bonds are long, and the subnetwork they form is weak. Even a small change in temperature may significantly change the H-bond potential which trapped protons and NH 4 ions.…”

Section: Discussionmentioning

confidence: 99%

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A Closer Look at Structural Relaxation in Superionic (NH₄)₄H₂(SeO₄)₃: ¹H NMR Studies

2021

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Structural relaxation and the role of molecular and proton dynamics in the electrolyte system, (NH 4 ) 4 H 2 (SeO 4 ) 3 (TeAHSe), are studied at ambient pressure, as a function of temperature and time, by using the solidstate 1 H NMR technique. Analysis of 1 H NMR spectra collected in the temperature range from 20 to 400 K yielded information about the dynamics of protons in the ordered and disordered crystalline TeAHSe phases. It has been shown that in the low-temperature phase TeAHSe is a proton conductor. In contrast, the electric charge carriers in the superionic phase are protons and NH 4 + ions. Therefore, the electrical conductivity in the superionic phase of TeAHSe is a combination of the chemical exchange of protons, proton diffusion within hydrogen bonds, and diffusion of ammonia cations in the bulk of the crystal. We also demonstrate that the enhanced charge transport in the superionic phase of TeAHSe mainly results from the NH 4 + cation diffusion process. The unique data from the time evolution of NMR spectra taken at a constant temperature just below the phase transition provide the first direct evidence of ammonium cations involvement in the lowtemperature structure recovery (structural relaxation). We proposed a scenario of the process of structural relaxation in the TeAHSe crystal as well as the origin of the phase transformation mechanism to the superionic stage.

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Ferric sulfophenyl phosphate bonded with phosphotungstic acid as a novel intercalated high-temperature inorganic-organic proton conductor

Wang

Sun

Hao

et al. 2018

Materials Chemistry and Physics

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Model for proton conductivity in phase III of (NH4)3H(SeO4)2 along the c-axis

Cited by 8 publications

References 35 publications

A closer look at superionic phase transition in (NH₄)₄H₂(SeO₄)₃: impedance spectroscopy under pressure

A closer look at superionic phase transition in (NH₄)₄H₂(SeO₄)₃: impedance spectroscopy under pressure

A Closer Look at Structural Relaxation in Superionic (NH₄)₄H₂(SeO₄)₃: ¹H NMR Studies

Ferric sulfophenyl phosphate bonded with phosphotungstic acid as a novel intercalated high-temperature inorganic-organic proton conductor

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Model for proton conductivity in phase III of (NH4)3H(SeO4)2 along the c-axis

Cited by 8 publications

References 35 publications

A closer look at superionic phase transition in (NH4)4H2(SeO4)3: impedance spectroscopy under pressure

A closer look at superionic phase transition in (NH4)4H2(SeO4)3: impedance spectroscopy under pressure

A Closer Look at Structural Relaxation in Superionic (NH4)4H2(SeO4)3: 1H NMR Studies

Ferric sulfophenyl phosphate bonded with phosphotungstic acid as a novel intercalated high-temperature inorganic-organic proton conductor

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Product

Resources

About

A closer look at superionic phase transition in (NH₄)₄H₂(SeO₄)₃: impedance spectroscopy under pressure

A closer look at superionic phase transition in (NH₄)₄H₂(SeO₄)₃: impedance spectroscopy under pressure

A Closer Look at Structural Relaxation in Superionic (NH₄)₄H₂(SeO₄)₃: ¹H NMR Studies