On the mean kinetic energy of the proton in strong hydrogen bonded systems

Finkelstein, Y.; Moreh, R.; Shang, Shun‐Li; Shchur, Ya.; Wang, Yi; Liu, Zhe

doi:10.1063/1.4940730

Cited by 12 publications

(21 citation statements)

References 61 publications

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“…As mentioned in the Introduction, in BZCY72 a large redshift of the OH-stretch infrared absorption band is observed in BZCY72, suggesting that strong hydrogen bond interactions mediate a fast proton transfer process [21,22]. At first glance, this situation seems to be similar to the case of the superprotonic conductor material trirubidium hydrogen bisulfate, Rb 3 H(SO 4 ) 2 , where a huge redshift of the OH stretch occurs combined with a low KE value of the H-atom, KE(H)= 113 meV, as verified by NCS measurements [91] and by DFT calculation [92]. The values of KE(H) = 113 meV, reported in [91], may be contrasted with values of KE(H) obtained, in a harmonic approximation as KE(H)=0.5 ZPE(H), from the values of ZPE(H) listed in tables 3 and 4, being 147±4 meV for the orthorhombic and 173±6 meV for the rhombohedral phase of BZCY72, respectively.…”

Section: Protons In Bzcy72supporting

confidence: 62%

Nuclear dynamics in BaZr_0.7Ce_0.2Y_0.1O_3−δ proton conductor as observed by neutron diffraction and Compton scattering

et al. 2020

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Concurrent neutron Compton scattering (NCS) and neutron diffraction experiments at temperatures between 70 K and 300 K have been performed on proton-conducting hydrated BaZr 0.7 Ce 0.2 Y 0.1 O 3−δ (BZCY72) fabricated by spark plasma sintering. A combined neutron data analysis, augmented with density functional theory modelling of lattice dynamics, has enabled, for the first time, a mass-selective appraisal of the combined thermal and nuclear quantum effect on nuclear dynamics and thermodynamic stability of this technologically important proton conducting perovskite oxide. The analysis suggests that the nuclear dynamics in hydrated BZCY72 is a result of a subtle interplay of harmonic, anharmonic and thermal effects, with the increased anharmonic character of the lattice dynamics above the orthorhombic to rhombohedral phase transition at 85 K. The anharmonic effect seems to be most pronounced in the case of oxygen and cerium. The analysis of the proton momentum distribution reveals that the concentration of the hydrogen in the BZCY72 lattice is constant across the orthorhombic to rhombohedral phase transition and further down to the room temperature. Moreover, the average hydrogen concentration obtained from our analysis of the mass-resolved neutron Compton scattering data seems to be commensurate with the total vacancy concentration in the BZCY72 framework. The calculation of the vibrational enthalpy of both phases allows obtaining the value of the enthalpy of the orthorhombic to the rhombohedral phase transition of −3.1±1 kJ mol −1 . Finally, our analysis of the nuclear kinetic energy of the proton obtained from NCS and the oxygen-oxygen distance distributions obtained from ND allows to conclude that BZCY72 in both the orthorhombic and rhombohedral phase at 70 K and 100 K respectively falls into the category of the KDP-type crystals where proton is probably under the influence of a double-well potential and forms hydrogen bonds of moderate strength. The obtained results have important ramifications for this technological important material. ( ) ·· · Materials most commonly used are solid-state solutions of Y-doped BaCeO 3 and BaZrO 3 [8-11]. Both endmembers exhibit outstanding protonic conductivities up to 10 -2 S cm −1 at 450°C [12].between chemical stability and easy fabrication, respectively offered by the end-members, special interest is taken in the composition BaZr 0.7 Ce 0.2 Y 0.1 O 3−δ (BZCY72) [6,13].In perovskite-type proton conductors, protons are not a part of the oxide lattice nor their stoichiometry. Instead, they are present as hydroxide defects, also known as protonic defects which they form together with oxide ions in equilibrium with an ambient stable hydrogen carrier. In most cases, water vapour is absorbed by the surface and dissociates into a hydroxide ion, which fills an oxygen vacancy, while the remaining proton forms a covalent bond with the surface oxygen [14][15][16].The crystal structure of BZCY72 has been precisely worked out by Mather et al employing combined highresolution neutron ...

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Section: Protons In Bzcy72supporting

confidence: 62%

Nuclear dynamics in BaZr_0.7Ce_0.2Y_0.1O_3−δ proton conductor as observed by neutron diffraction and Compton scattering

et al. 2020

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“…In addition, estimates of Ke(X) for pure metallic Debye solids are given in Figure 3 (see Ref. [7]) showing that Ke of covalently bonded metals in the present study are clearly higher than those in ionic and metallic solids. This observation strengthens the validity of our approach of deducing atomic KE values.…”

Section: Y Finkelstein Et Al Journal Of Materials Science and Chemimentioning

confidence: 99%

“…Calculated (full circles) and experimental (ECS-triangles, NRPS-Square) room temperature kinetic energies of the elements in the oxide samples (current study-red), in ferroelectrics and protonic superconductors (green [7] [21]) and in pure metals. [7] Solid curves are drawn to lead the eye. ) compared to that of the crystalline form (the supercell calculation), which could indicate a stronger Ti-O stretching in the nano-particles form.…”

Section: Y Finkelstein Et Al Journal Of Materials Science and Chemimentioning

confidence: 99%

“…This later method assumes the harmonic approximation (HA) and a decoupling between the various modes contributing to <KE>, the input data are taken from experiment [10]. Note that the SE approach utilizing simulated PVDOS was found to correctly reproduce Ke(H) values even in strongly anharmonic systems such as in KDP type crystals [7], Rb 3 H(SO 4 ) 2 [7] and H 2 O@Beryl [8], indicating that anharmonicity has probably only small effect on the atomic kinetic energy [10].…”

Section: Introductionmentioning

confidence: 99%

“…Recently, calculations comprising VDOS and PVDOS, were used to study average atomic kinetic energies, <KE>, in some benchmark systems involving hydrogen bonds (HBs), e.g. in ice Ih and liquid water [5], highly compressed ice VII [6], ferroelectric crystals of the KDP-type [7], the Rb 3 H(SO 4 ) 2 superprotonic conductor [7] and water nano-confined in Beryl [8]. Very recently, the same idea was also applied for studying the anisotropy of Ke(H) in the ferro-and para-electric phases of CDP (CsH 2 PO 4 ) [9].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

On the Atomic Kinetic Energies in Ceramic Oxides

Finkelstein¹,

Moreh²,

Shneck³

2017

MSCE

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We calculated the mean atomic kinetic energy, , of the X atom (X = Si, Ti, Hf, O) in some ceramic oxides, SiO 2 , TiO 2 and HfO 2 using the published partial vibrational density of states (PVDOS). These were simulated by means of lattice dynamics, molecular dynamics and density functional theory.The predicted values are compared to those recently obtained by electron Compton scattering (ECS), with an overall good agreement of ~4%. In accord with calculations, the ECS measurements reveal a small, but detectable, dependence of on the fine structural details of the oxide, e.g. whether it is in a crystalline or amorphous form, and whether it exhibits surface or bulk characteristics. This study illustrates the limitations and the potential of PVDOS simulations in predicting experimental atomic kinetic energies, and can be viewed as a promising approach for elucidating valuable structural and dynamical information of ceramic oxides and other materials.

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On H-dynamics of supercooled water confined in nanoporous silica

Finkelstein

Moreh

2019

Chemical Physics

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On the mean kinetic energy of the proton in strong hydrogen bonded systems

Cited by 12 publications

References 61 publications

Nuclear dynamics in BaZr_0.7Ce_0.2Y_0.1O_3−δ proton conductor as observed by neutron diffraction and Compton scattering

Nuclear dynamics in BaZr_0.7Ce_0.2Y_0.1O_3−δ proton conductor as observed by neutron diffraction and Compton scattering

On the Atomic Kinetic Energies in Ceramic Oxides

On H-dynamics of supercooled water confined in nanoporous silica

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On the mean kinetic energy of the proton in strong hydrogen bonded systems

Cited by 12 publications

References 61 publications

Nuclear dynamics in BaZr0.7Ce0.2Y0.1O3−δ proton conductor as observed by neutron diffraction and Compton scattering

Nuclear dynamics in BaZr0.7Ce0.2Y0.1O3−δ proton conductor as observed by neutron diffraction and Compton scattering

On the Atomic Kinetic Energies in Ceramic Oxides

On H-dynamics of supercooled water confined in nanoporous silica

Contact Info

Product

Resources

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Nuclear dynamics in BaZr_0.7Ce_0.2Y_0.1O_3−δ proton conductor as observed by neutron diffraction and Compton scattering

Nuclear dynamics in BaZr_0.7Ce_0.2Y_0.1O_3−δ proton conductor as observed by neutron diffraction and Compton scattering