Strain Driven Two-Dimensional Phase Transition in PbSnF4 Superionic Conductor

1994 ◽  
Vol 369 ◽  
Author(s):  
Georges Denes ◽  
M.C. Madamba ◽  
J.M. Parris
Keyword(s):  
Phase Transition ◽  
Structural Change ◽  
Chemical Composition ◽  
Lead Nitrate ◽  
Unit Cell ◽  
Minor Amount ◽  
Two Dimensional ◽  
Detectable Change ◽  
A Minor ◽  
Nonuniform Strain

AbstractWhen a minor amount of HF is added to the SnF2 reacted with lead nitrate in aqueous solutions to prepare PbSnF4, a phase transition from tetragonal α-PbSnF4 to orthorhombíc o-PbSnF4 takes place. The transition is essentially bidimensional and takes place in the (a,b) plane of the unit-cell. The compactness of the structure increases at the transition. No essential structural change occurs: the transition is most likely displacive and it is driven by bidimensional nonuniform strain acting along the aand baxes of the unit-cell. This transition is similar to ferroic transitions (in this case, paraelastic → ferroelastic). No detectable change of chemical composition occurs at the transition, and the reason why the presence of HF in the reaction mixture causes the transition remains unknown.

Two phases of {[CsPH(η6-2,4,6- t Bu3C6H2)]2(η3-toluene)0.5} x : their structures and interconversions

2000 ◽  
Vol 56 (2) ◽  
pp. 210-214
Author(s):  
Thomas E. Concolino ◽  
Kin-Chung Lam ◽  
Ilia A. Guzei ◽  
Arnold L. Rheingold ◽  
Gerd W. Rabe
Keyword(s):  
Phase Transition ◽  
Solid State ◽  
Unit Cell Volume ◽  
Structural Features ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Disorder Phase Transition ◽  
Two Phases ◽  
A Minor

The solvent-bridged caesium phosphide {[CsPH(η 6-2,4,6- t Bu3C6H2)]2(η 3-toluene)0.5} x , catena-[(μ-η3-toluene)-bis[caesium(2,4,6-tri-tert-butylphenylphosphide)]], undergoes a reversible solid-state, order–disorder phase transition characterized by the doubling of the unit-cell volume at low temperature achieved by doubling one unit-cell vector. The unit-cell parameters at 293 (2) K (form A) are: a = 11.147 (4), b = 14.615 (4), c = 14.806 (5) Å, α = 70.57 (3), β = 71.85 (3), γ = 72.93 (2)°, V = 2112.5 (12) Å3, Z = 2, ρcalc = 1.362 g cm−3, R 1 = 0.0513 for 5462 reflections, wR 2 = 0.0947 for all data. The unit-cell parameters at 173 (2) K (form B) are: a = 14.6241 (3), b = 14.7393 (3), c = 22.0720 (4) Å, α = 72.2117 (7), β = 73.3659 (8), γ = 70.2953 (7)°, V = 4174.8 (2) Å3, Z = 4, ρcalc = 1.379 g cm−3, R 1 = 0.0405 for 14 010 reflections, wR 2 = 0.1326 for all data. With a minor change, the key structural features discussed previously for form A [Rabe et al. (1998). Inorg. Chem. 37, 4235–4245] remain unchanged. The η 3-toluene ligand is observed to be disordered at 293 (2) K and ordered at 173 (2) K, with the order–disorder phase transition occurring at approximately 278 (2) K.

scholarly journals High-Pressure Raman and Infrared Spectroscopic Study of Prehnite

Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 312
Author(s):  
Nancy L. Ross ◽  
Theresa A. Detrie ◽  
Zhenxian Liu
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Structural Change ◽  
Chemical Composition ◽  
Infrared Spectra ◽  
Infrared Spectroscopic Study ◽  
Framework Structure ◽  
Natural Sample ◽  
Reversible Phase Transition ◽  
Reversible Phase

High-pressure Raman and infrared spectra of a natural sample of prehnite, with a chemical composition of Ca2(Al0.74,Fe0.26)2Si3O10(OH)2, are presented. Analyses of the spectra indicate that prehnite undergoes a reversible structural change between 6 and 8 GPa that is most likely associated with a subtle alteration in the orientation and/or deformation of the polyhedra comprising the framework of the structure. At pressures in excess of ~11 GPa, the high-pressure spectra indicate that prehnite undergoes a reversible phase transition involving the collapse of the framework structure.

Temperature Effect on the Two-Dimensional Phase Transition Kinetics of Adenine Adsorbed at the Hg Electrode/Aqueous Solution Interface

2003 ◽  
Vol 68 (8) ◽  
pp. 1407-1419 ◽  
Author(s):  
Claudio Fontanesi ◽  
Roberto Andreoli ◽  
Luca Benedetti ◽  
Roberto Giovanardi ◽  
Paolo Ferrarini
Keyword(s):  
Phase Transition ◽  
Aqueous Solution ◽  
Phase Change ◽  
Temperature Effect ◽  
Transition Rate ◽  
Effect Of Temperature ◽  
Two Dimensional ◽  
Solution Interface ◽  
Phase Transition Kinetics ◽  
Kinetics Of

The kinetics of the liquid-like → solid-like 2D phase transition of adenine adsorbed at the Hg/aqueous solution interface is studied. Attention is focused on the effect of temperature on the rate of phase change; an increase in temperature is found to cause a decrease of transition rate.

scholarly journals Avocado-Derived Biomass: Chemical Composition and Antioxidant Potential

Proceedings ◽  
2020 ◽  
Vol 70 (1) ◽  
pp. 100
Author(s):  
Minerva C. García-Vargas ◽  
María del Mar Contreras ◽  
Irene Gómez-Cruz ◽  
Juan Miguel Romero-García ◽  
Eulogio Castro
Keyword(s):  
Chemical Composition ◽  
Phenolic Content ◽  
Antioxidant Properties ◽  
Total Phenolic ◽  
Nutritional Properties ◽  
Aqueous Fraction ◽  
Extraction Solvent ◽  
Main Components ◽  
A Minor ◽  
Derivatives Of

Avocado has become fashionable due to its great organoleptic and nutritional properties. It is consumed as a fresh product and it is also processed to obtain salad oil and guacamole. In all cases, the only usable portion is the pulp. Therefore, to be a more sustainable and profitable agribusiness, it is important to recognize which compounds from the peel and the stone waste can be converted into valuable bio-products. Therefore, their chemical composition was determined according to the National Renewable Energy Laboratory, the total phenolic content by the Folin-Ciocalteu method and the antioxidant properties by the FRAP and TEAC assays. The main components of the peel and stone were acid-insoluble lignin (35.0% and 15.3%, respectively), polymeric sugars (23.6% and 43.9%, respectively), and the aqueous extractives (15.5% and 16.9%, respectively). Both biomasses contain lipids and protein, but a minor proportion (<6%). The valorization of lignin and sugars is of interest given the high content; stones are a rich source of glucose (93.2% of the polymeric fraction), which could be used to obtain biofuels or derivatives of interest. The extractive fraction of the peel contained the highest number of phenolic compounds (4.7 g/100 g biomass), mainly concentrated in the aqueous fraction (i.e., 87%) compared to the ethanol one, which was subsequently extracted. It correlated with major antioxidant activity and, therefore, the peel can be applied to obtain antioxidants and water can be used as an environmentally friendly extraction solvent.

scholarly journals Odour-active compounds in liquid malt extracts for the baking industry

2021 ◽  
Author(s):  
Nadine S. Rögner ◽  
Veronika Mall ◽  
Martin Steinhaus
Keyword(s):  
Threshold Value ◽  
Starting Material ◽  
Minor Amount ◽  
Malt Extract ◽  
Important Process ◽  
Gas Chromatography Olfactometry ◽  
Odour Threshold ◽  
A Minor ◽  
Baking Industry ◽  
Insight Into

AbstractAn odorant screening by gas chromatography–olfactometry (GC–O) and a crude aroma extract dilution analysis (AEDA) applied to the volatiles isolated from a light and a dark liquid malt extract (LME) by solvent extraction and solvent-assisted flavour evaporation (SAFE) identified 28 odorants. Fifteen major odorants were subsequently quantitated and odour activity values (OAVs) were calculated as ratio of the concentration to the respective odour threshold value (OTV). Important odorants in the light LME included 3-(methylsulfanyl)propanal (OAV 1500), (E)-β-damascenone (OAV 430), and 4-ethenyl-2-methoxyphenol (OAV 91). In the dark LME, sotolon (OAV 780), 3-(methylsulfanyl)propanal (OAV 550), (E)-β-damascenone (OAV 410), acetic acid (OAV 160), and maltol (OAV 120) were of particular importance. To get an insight into the changes during malt extract production, the quantitations were extended to the malt used as the starting material for both LMEs. Addition of a minor amount of water to malt before volatile extraction was shown to be effective to cover the free as well as the bound malt odorants. Results showed that some LME odorants originated from the starting material whereas others were formed during processing. Important process-induced LME odorants included (E)-β-damascenone and 4-ethenyl-2-methoxyphenol in the light LME as well as maltol, sotolon, (E)-β-damascenone, and 2-methoxyphenol in the dark LME. In summary, the odorant formation during LME production was shown to be more important than the transfer of odorants from the malt.

scholarly journals Quantum effects on the BKT phase transition of two-dimensional Josephson arrays

2000 ◽  
Vol 61 (17) ◽  
pp. 11289-11292 ◽  
Author(s):  
Alessandro Cuccoli ◽  
Andrea Fubini ◽  
Valerio Tognetti ◽  
Ruggero Vaia
Keyword(s):  
Phase Transition ◽  
Quantum Effects ◽  
Two Dimensional ◽  
Josephson Arrays ◽  
Bkt Phase Transition

Numerical Analysis of Two-Phase Pipe Flow of Liquid Helium Using Multi-Fluid Model

2001 ◽  
Vol 123 (4) ◽  
pp. 811-818 ◽  
Author(s):  
Jun Ishimoto ◽  
Mamoru Oike ◽  
Kenjiro Kamijo
Keyword(s):  
Phase Transition ◽  
Gas Phase ◽  
Liquid Helium ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Numerical Results ◽  
Phase Flow ◽  
Two Dimensional ◽  
Two Phase ◽  
Normal Fluid

The two-dimensional characteristics of the vapor-liquid two-phase flow of liquid helium in a pipe are numerically investigated to realize the further development and high performance of new cryogenic engineering applications. First, the governing equations of the two-phase flow of liquid helium based on the unsteady thermal nonequilibrium multi-fluid model are presented and several flow characteristics are numerically calculated, taking into account the effect of superfluidity. Based on the numerical results, the two-dimensional structure of the two-phase flow of liquid helium is shown in detail, and it is also found that the phase transition of the normal fluid to the superfluid and the generation of superfluid counterflow against normal fluid flow are conspicuous in the large gas phase volume fraction region where the liquid to gas phase change actively occurs. Furthermore, it is clarified that the mechanism of the He I to He II phase transition caused by the temperature decrease is due to the deprivation of latent heat for vaporization from the liquid phase. According to these theoretical results, the fundamental characteristics of the cryogenic two-phase flow are predicted. The numerical results obtained should contribute to the realization of advanced cryogenic industrial applications.

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