Disorder of (NH4)3H(SO4)2 in the high-temperature phase I

2011 ◽  
Vol 67 (2) ◽  
pp. 116-121 ◽  
Author(s):  
Yoo Jung Sohn ◽  
Karine M. Sparta ◽  
Martin Meven ◽  
Gernot Heger
Keyword(s):  
High Temperature ◽  
Hydrogen Bonds ◽  
Phase I ◽  
Careful Consideration ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Atom Model ◽  
Disordered Crystal ◽  
Proton Migration ◽  
Atom Position

The highly disordered crystal structure of triammonium hydrogen disulfate, (NH4)3H(SO4)2, in the high-temperature phase I was studied using single-crystal neutron diffraction. It is known that the O atom involved in hydrogen bonding between neighbouring SO4 tetrahedra is disordered and takes a split-atom position, building a two-dimensional hydrogen-bond network in the (001) plane. The H atoms in these SO4–H—SO4 hydrogen bonds are disordered and hence refined with a split-atom model. Moreover, from the much larger anisotropic mean-square displacements of ammonium protons the NH_4^+ groups were refined with a reasonable split-atom model, and their motional behaviour was also analysed by rigid-body treatment. Finally, careful consideration was given to show possible supplementary proton migration between the ammonium protons and those of the hydrogen bonds in this high-temperature phase.

Temperature dependence of intramolecular disorder in the high-temperature phase of poly(tetrafluoroethylene) (phase I)

1988 ◽  
Vol 21 (4) ◽  
pp. 1174-1176 ◽  
Author(s):  
C. De Rosa ◽  
G. Guerra ◽  
V. Petraccone ◽  
R. Centore ◽  
P. Corradini
Keyword(s):  
High Temperature ◽  
Phase I ◽  
Temperature Dependence ◽  
High Temperature Phase ◽  
Temperature Phase

Hydrogen-Bonding and Phase Transitions in Proton-Conducting Solid Acids

1998 ◽  
Vol 547 ◽  
Author(s):  
Sossina M. Haile
Keyword(s):  
High Temperature ◽  
Hydrogen Bonds ◽  
Solid Acid ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Temperature Structure ◽  
System A ◽  
Superprotonic Phase ◽  
Oxygen Site ◽  
Oxygen Atoms

AbstractFrom an investigation of the structures and electrical properties of compounds in the CsHSO4 - CsH2PO4 system, a simple model is presented for predicting whether or not a solid acid will undergo a structural transition to a disordered, superprotonic phase. Such a transition was measured in ß-Cs3(HSO4)2(H2-x(SxP1-x)O4), α-Cs3(HSO4)2(H2PO4) and Cs2(HSO4)(H2PO4), but not CsH2PO4. It is proposed that entropy drives any solid acid to a high-temperature structure in which the oxygen atoms participate equally in forming hydrogen bonds. If the H:XO4 ratio is not precisely 2:1, such chemical equivalence of oxygen atoms can only be achieved if the structure transforms to a state in which proton occupancies at hydrogen bonds are less than one and/or oxygen site occupancies are less than one. This disorder simultaneously leads to fast proton transport in the high-temperature phase, and thus superprotonic conductivity.

Ab initio structure determination of the high-temperature phase of anhydrous caffeine by X-ray powder diffraction

2005 ◽  
Vol 61 (3) ◽  
pp. 329-334 ◽  
Author(s):  
Patrick Derollez ◽  
Natália T. Correia ◽  
Florence Danède ◽  
Frédéric Capet ◽  
Frédéric Affouard ◽  
...  
Keyword(s):  
High Temperature ◽  
Phase I ◽  
Metastable State ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Rietveld Refinements ◽  
X Ray ◽  
Ab Initio Structure

The high-temperature phase I of anhydrous caffeine was obtained by heating and annealing the purified commercial form II at 450 K. This phase I can be maintained at low temperature in a metastable state. A powder X-ray diffraction pattern was recorded at 278 K with a laboratory diffractometer equipped with an INEL curved position-sensitive detector CPS120. Phase I is dynamically orientationally disordered (the so-called plastic phase). The Rietveld refinements were achieved with rigid-body constraints. It was assumed that on each site, a molecule can adopt three preferential orientations with equal occupation probability. Under a deep undercooling of phase I, below 250 K, the metastable state enters in a glassy crystal state.

Phase Transitions in CsSnCl3 and CsPbBr3 An NMR and NQR Study

1991 ◽  
Vol 46 (4) ◽  
pp. 329-336 ◽  
Author(s):  
Surendra Sharma ◽  
Norbert Weiden ◽  
Alarich Weiss
Keyword(s):  
Phase Transitions ◽  
High Temperature ◽  
Phase I ◽  
Powder Diffraction ◽  
Perovskite Structure ◽  
Room Temperature ◽  
Monoclinic Phase ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
X Ray

Abstract The phase transitions in CsSnCl3 and CsPbBr3 have been studied by X-ray powder diffraction, by 81Br-NQR and by 'H-, 119Sn-, and 113Cs-NMR. At room temperature in air CsSnCl3 forms a hydrate which can be dehydrated to the monoclinic phase II of CsSnCl3. The high temperature phase I has the Perovskite structure, as the X-ray and NMR experiments show. The three phases of CsPbBr3, known from literature, have been corroborated. The results are discussed in the framework of the group ABX3, A = alkalimetal ion, B = IV main group ion, and X = Halogen ion

scholarly journals Disorder of the (NH4)3H(SO4)2in the high-temperature phase I: single-crystal neutron diffraction

2010 ◽  
Vol 66 (a1) ◽  
pp. s279-s279 ◽  
Author(s):  
Yoo Jung Sohn ◽  
Karine Sparta ◽  
Sebastian Prinz ◽  
Martin Meven ◽  
Helmut Klapper ◽  
...  
Keyword(s):  
High Temperature ◽  
Neutron Diffraction ◽  
Phase I ◽  
Single Crystal ◽  
High Temperature Phase ◽  
Temperature Phase

scholarly journals The order/disorder phase transition of hypophosphorous acid H3PO2

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Martin Nastran ◽  
Berthold Stöger
Keyword(s):  
Phase Transition ◽  
Hydrogen Bonding ◽  
High Temperature ◽  
Low Temperature ◽  
Hydrogen Bonds ◽  
Rotation Axis ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Hypophosphorous Acid ◽  
Disorder Phase Transition

Abstract Hypophosphorous acid, H3PO2 is dimorphic with a phase transition in the 200–225 K range. The H3PO2 molecules are connected by hydrogen bonding to infinite chains extending in the [100] direction. In the high-temperature phase (P21212, Z ′ = 1 2 ${Z}^{\prime }=\frac{1}{2}$ ), the hydrogen bonds are disordered about a two-fold rotation axis. On cooling below the phase transition temperature, the hydrogen bonds become ordered, resulting in a symmetry reduction of the klassengleiche type of index 2. In the low-temperature phase (P212121, Z ′ = 1 ${Z}^{\prime }=1$ ), the c parameter is doubled with respect to the high-temperature phase. The hydrogen-bonding topology of the high- and low-temperature phases are double-infinite directed and undirected linear graphs, respectively.

Structural Study of TlH2PO4 and TlD2PO4 in the High Temperature Phase

1995 ◽  
Vol 5 (7) ◽  
pp. 763-769 ◽  
Author(s):  
S. Rios ◽  
W. Paulus ◽  
A. Cousson ◽  
M. Quilichini ◽  
G. Heger ◽  
...  
Keyword(s):  
High Temperature ◽  
Structural Study ◽  
High Temperature Phase ◽  
Temperature Phase

LATTICE DYNAMICS CALCULATIONS FOR SOLID BIPHENYL IN THE HIGH TEMPERATURE PHASE

1981 ◽  
Vol 42 (C6) ◽  
pp. C6-599-C6-601 ◽  
Author(s):  
T. Wasiutynski ◽  
I. Natkaniec ◽  
A. I. Belushkin
Keyword(s):  
High Temperature ◽  
Lattice Dynamics ◽  
High Temperature Phase ◽  
Temperature Phase
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