scholarly journals Low temperature oxygen diffusion mechanisms in Nd2NiO4+δ and Pr2NiO4+δvia large anharmonic displacements, explored by single crystal neutron diffraction

2015 ◽  
Vol 3 (42) ◽  
pp. 21140-21148 ◽  
Author(s):  
M. Ceretti ◽  
O. Wahyudi ◽  
A. Cousson ◽  
A. Villesuzanne ◽  
M. Meven ◽  
...  
Keyword(s):  
Low Temperature ◽  
Neutron Diffraction ◽  
Neutron Scattering ◽  
Single Crystal ◽  
Oxygen Diffusion ◽  
Apical Oxygen ◽  
Diffusion Pathway ◽  
Energy Diffusion ◽  
Diffusion Mechanisms ◽  
Oxygen Atoms

Quasi-continuous shallow energy diffusion pathway and anharmonic double potential of the apical oxygen atoms in Pr2NiO4.25 explored by single crystal neutron scattering at 400 °C.

scholarly journals Neutron Diffraction Investigation on the Symmetrical Hydrogen Bond in K3H(SO4)2

2014 ◽  
Vol 70 (a1) ◽  
pp. C1114-C1114
Author(s):  
In-Hwan Oh ◽  
Yoo-Jung Sohn ◽  
Martin Meven ◽  
Gernot Heger
Keyword(s):  
Hydrogen Bond ◽  
Low Temperature ◽  
Neutron Diffraction ◽  
Single Crystal ◽  
Bond Length ◽  
Title Compound ◽  
Monoclinic Space Group ◽  
Intermediate Form ◽  
Hydrogen Atoms ◽  
Oxygen Atoms

In this work, we present a structure investigation on K3H(SO4)2 by single crystal neutron diffraction. Letovicite with a chemical composition (NH4)3H(SO4)2 belongs to a large family of M3(H,D)(XO4)2 compounds, where M = K+, Rb+, (NH4)+, Cs+, Tl+ and X = Se6+ and S6+. This compound crystallizes in the monoclinic space group A2/a with a = 9.789(7) Å, b = 5.6815(9) Å, c = 14.703(2) Å and β = 103.03(4)0at 300K. At 2.3K, the lattice parameters are a = 9.687(20) Å, b = 5.648(13) Å, c = 14.613(9) Å and β = 103.23(14)0. Data at 2.3K were measured up to (sinθ/λ) = 0.807Å-1 with the single crystal neutron diffractormeter HEiDi at the FRM-II, Germany. H/D shows a dynamic disorder at high temperature, which can be related to very high proton conductivity. In letovicite, two types of disorder related with hydrogen atoms are reported [1]. Although letovicite shows various phase transitions owing to the proton ordering at low temperature, K3H(SO4)2, without the possibility of an orientational disorder of NH4+, undergoes no phase transition at low temperature. At room temperature, the title compound is isostructural to lectovicite, and has an inversion center in the middle of the SO4-H-SO4 dimer. The bond length, 2.483(3) Å, and bond angle, 1800, support the hypothesis that the disordered proton shows a double-well potential, if the distance between the oxygen atoms of the hydrogen bond Ro-o are longer than a critical bond length rc(2.47 Å for protons and 2.40 Å for deuterons) [2]. However, it is not easy to determine if the hydrogen bond is a low-barrier hydrogen bond (LBHB) or centered hydrogen bond (centered HB). Based on an analysis of the anisotropic parameters, the bond lengths and elongation of the hydrogen atom toward the two oxygen atoms by neutron single crystal diffraction experiments at 300K and 2.3K, it seems that the hydrogen bond in the title compound can be classified as a centered hydrogen bond or intermediate form between a cigar-like shape and the disk-like shape [3].

Infrared furnace for in situ neutron single-crystal diffraction studies in controlled gas atmospheres at high temperatures

2021 ◽  
Vol 54 (3) ◽  
Author(s):  
Fernando Magro ◽  
Monica Ceretti ◽  
Martin Meven ◽  
Werner Paulus
Keyword(s):  
Neutron Diffraction ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Single Crystal ◽  
Oxygen Diffusion ◽  
Room Temperature ◽  
Structural Changes ◽  
High Temperature Furnace ◽  
Diffusion Mechanisms

To understand oxygen diffusion mechanisms in non-stoichiometric oxides, the possibility to explore structural changes as a function of the oxygen partial pressure with temperature and related oxygen bulk stoichiometry is mandatory. This article reports on the realization of a high-temperature furnace, suitable for single-crystal neutron diffraction, working continuously at temperatures of up to 1000°C at different and adjustable partial gas pressures of up to 2 bar (1 bar = 100 kPa). This allows exploration of the phase diagrams of non-stoichiometric oxides under in situ conditions and controlled oxygen partial pressure. As a pilot study, the structural changes of Pr2NiO4+δ were explored at room temperature (δ ≃ 0.24) and at 900°C under 1 bar P(O2) (δ ≃ 0.13) as well as under secondary vacuum (approximately 10−5 mbar) conditions yielding a δ close to zero. The strong anharmonic displacements of the apical oxygen atoms along the [110] shallow diffusion pathway, which were previously observed at room temperature and 400°C, become more isotropic at 900°C. The study shows that the anisotropic oxygen displacements, here related to lattice instabilities, play a major role in understanding oxygen diffusion pathways and related activation energies at moderate temperatures. This also shows the importance of the availability of reaction cells for single-crystal neutron diffraction to explore the phase diagram and associated structural changes of non-stoichiometric oxygen ion conductors and respective diffusion mechanisms.

Low-frequency single-crystal Raman, far-infrared, and inelastic neutron scattering studies of acetanilide at low temperature

1991 ◽  
Vol 95 (13) ◽  
pp. 5281-5286 ◽  
Author(s):  
Clifford T. Johnston ◽  
Stephen F. Agnew ◽  
Juergen Eckert ◽  
Llewellyn H. Jones ◽  
Basil I. Swanson ◽  
...  
Keyword(s):  
Low Temperature ◽  
Neutron Scattering ◽  
Single Crystal ◽  
Inelastic Neutron Scattering ◽  
Low Frequency ◽  
Far Infrared ◽  
Inelastic Neutron

X-ray and neutron diffraction investigation at 298 K of NH4I · NH3 and ND4I · ND3 containing the cation H3N – H … NH3+ and D3N – D … ND3+

1992 ◽  
Vol 200 (3-4) ◽  
Author(s):  
H. J. Berthold ◽  
E. Vonholdt ◽  
R. Wartchow ◽  
T. Vogt
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Neutron Diffraction ◽  
Single Crystal ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
Single Crystal Structure ◽  
X Ray ◽  
Single Crystal Structure Analysis

AbstractNHA single crystal structure analysis of NThe deuterated compound NThe structures of the ordered low temperature phases will be reported separately.

A Re-investigation of the Crystal Structure of the Perovskite PbZrO3 by X-ray and Neutron Diffraction

1997 ◽  
Vol 53 (1) ◽  
pp. 135-142 ◽  
Author(s):  
D. L. Corker ◽  
A. M. Glazer ◽  
J. Dec ◽  
K. Roleder ◽  
R. W. Whatmore
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Neutron Diffraction ◽  
Single Crystal ◽  
Lead Zirconate ◽  
Conclusive Evidence ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Investigations

The crystal structure of the perovskite lead zirconate PbZrO3 has been redetermined using single-crystal X-ray diffraction (Mo Kα radiation, λ = 0.71069 Å). Single-crystal data at 100 K: space group. Pbam, a = 5.884 (1), b = 11.787 (3), c = 8.231 (2) Å, V = 570.85 Å3 with Z = 8, μ = 612.6 cm−1, D x = 8.06 Mg m−3, F(000) = 1168, final R = 0.033, wR = 0.061 over 555 reflections with I > 2σ(I). An investigation is made into previous contradicting reports of a possible disorder in the O atoms and their origin by examining the crystal pseudo-symmetry. Information distinguishing an ordered and disordered oxygen substructure is shown to reside in weak l odd reflections. Because of their extremely low intensities these reflections have not contributed sufficiently in previous X-ray structure investigations and hence, to date, conclusive evidence differentiating between ordered and disordered models has not been possible. By collecting single-crystal X-ray data at low temperature and by using exceptionally long scans on selected hkl, l odd, reflections, a new accurate structure determination is presented and discussed, showing the true ordered oxygen positions. Because of the large difference in scattering factors between lead and oxygen when using X-rays, a neutron diffraction Rietveld refinement using polycrystalline samples (D1A instrument, ILL, λ = 1.90788 Å) is also reported as further evidence to support the true ordered oxygen structure revealed by the low-temperature X-ray analysis.

Observation of Low Temperature Oxygen Diffusion in Deuterium-Doped YBa2Cu3O6 Single Crystal by SIMS

1995 ◽  
pp. 385-388
Author(s):  
Shigeki Tsukui ◽  
Takao Yamamoto ◽  
Motoaki Adachi ◽  
Yoshihiko Shono ◽  
Keisuke Kawabata ◽  
...  
Keyword(s):  
Low Temperature ◽  
Single Crystal ◽  
Oxygen Diffusion

Low-Temperature Single-Crystal Raman and Neutron-Diffraction Study of the Hydrogenous Ammonium Copper(II) Tutton Salt and the Deuterated Analogue in the Metastable State

2003 ◽  
Vol 42 (25) ◽  
pp. 8524-8533 ◽  
Author(s):  
Christopher Dobe ◽  
Graham Carver ◽  
Hans-Beat Bürgi ◽  
Philip L. W. Tregenna-Piggott ◽  
Garry J. McIntyre ◽  
...  
Keyword(s):  
Low Temperature ◽  
Neutron Diffraction ◽  
Single Crystal ◽  
Diffraction Study ◽  
Metastable State ◽  
Neutron Diffraction Study ◽  
Deuterated Analogue
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