Evidence for the charge-ordered state and phase separation at room temperature in half-doped La0.5Ca0.5MnO3 films

2006 ◽  
Vol 89 (5) ◽  
pp. 052502 ◽  
Author(s):  
S. Y. Park ◽  
Y. H. Hyun ◽  
Y. P. Lee ◽  
V. L. Svetchnikov ◽  
K. W. Kim ◽  
...  
Keyword(s):  
Phase Separation ◽  
Room Temperature ◽  
Ordered State

Metal-Alkali Catalytic Valorization of Lignocellulose Towards Aromatics and Small Molecular Alcohols and Acids in a Holistic Approach

2021 ◽  
Author(s):  
Wei Lv ◽  
Yuting Zhu ◽  
Weiqi Mai ◽  
Changhui Zhu ◽  
Qifeng Pi ◽  
...  
Keyword(s):  
Phase Separation ◽  
Room Temperature ◽  
Holistic Approach ◽  
Woody Biomass ◽  
Solvent System ◽  
Effective Strategy ◽  
One Pot ◽  
Reaction Phase ◽  
Alkali Catalysts ◽  
O Phase

Abstract In this work, we developed an approach of one-pot completely catalytic conversion of woody biomass into two value product streams: lignin-derived aromatics (68.54% monomer and 29.65% oligomer yields of lignin) and (semi-)cellulose-derived small molecular alcohols (about 59.60% of biomass mass). These could be afforded by conducting lignocellulose depolymerization over metal-alkaline catalysts in a mixture n-butanol/H2O solvent system at 250 °C and 30 bar H2. In the valorization process, the homogenous mixture of n-butanol-H2O solvents extract and depolymerize both lignin and hemicellulose, while the catalysts and H2 are essential to cleave the inter-/intramolecular linkages of lignocellulose into target products. After the reaction, phase separation of n-butanol and H2O takes place when systematic temperature at room temperature, providing a mild and effective strategy to isolate lignin-derived aromatics (n-butanol phase) from small molecular alcohols/acids (aqueous phase). Ru/C and alkali catalysts are collected by filtration from n-butanol phase and H2O phase, respectively. Meanwhile, the effect of metal-alkali coupled catalysts enables facilitating the cleavage of β-O-4 linkage of lignin and increasing the attainability of (semi-)cellulose-derived oligomers and the small molecular alcohols. This catalytic system provides a versatile valorization approach for biomass catalytic to bio-based chemicals.

In situ high temperature X-ray diffraction study of the kinetics of phase separation in the uranium-plutonium mixed oxide (U0.55Pu0.45)O2-x

2014 ◽  
Vol 1645 ◽  
Author(s):  
Romain VAUCHY ◽  
Renaud.C. BELIN ◽  
Anne-Charlotte ROBISSON ◽  
Fiqiri HODAJ
Keyword(s):  
Phase Separation ◽  
Room Temperature ◽  
Mixed Oxides ◽  
Oxygen Stoichiometry ◽  
X Ray Diffraction ◽  
Fundamental Interest ◽  
X Ray ◽  
Uranium Plutonium ◽  
Kinetics Of

ABSTRACTUranium-plutonium mixed oxides incorporating high amounts of plutonium are considered for future nuclear reactors. For plutonium content higher than 20%, a phase separation occurs, depending on the temperature and on the oxygen stoichiometry. This phase separation phenomenon is still not precisely described, especially at high plutonium content. Here, using an original in situ fast X-ray diffraction device dedicated to radioactive materials, we evidenced a phase separation occurring during rapid cooling from 1773 K to room temperature at the rate of 0.05 and 2 K per second for a (U0.55Pu0.45)O2-x compound under a reducing atmosphere. The results show that the cooling rate does not impact the lattice parameters of the obtained phases at room temperature but their fraction. In addition to their obvious fundamental interest, these results are of utmost importance in the prospect of using uranium-plutonium mixed oxides with high plutonium content as nuclear fuels.

Phase Separation and Destabilization of the Charge-Ordered State in Cr-Doped Manganites

2001 ◽  
Vol 70 (1) ◽  
pp. 267-271 ◽  
Author(s):  
Ryuichi Shoji ◽  
Shigeo Mori ◽  
Naoki Yamamoto ◽  
Akihiko Machida ◽  
Yutaka Moritomo ◽  
...  
Keyword(s):  
Phase Separation ◽  
Doped Manganites ◽  
Ordered State

Elektronische Wechselwirkung zwischen Kohlenmonoxyd und aufgedampften Ge-Filmen mit reiner oder mit Sauerstoff vorbelegter Oberfläche

1963 ◽  
Vol 18 (5) ◽  
pp. 633-638
Author(s):  
R. Suhrmann ◽  
M. Kruel ◽  
G. Wedler
Keyword(s):  
Room Temperature ◽  
High Vacuum ◽  
Electron Donors ◽  
Band Model ◽  
Electronic Interaction ◽  
Electric Resistance ◽  
Before And After ◽  
Adsorption Of Co ◽  
Higher Temperature ◽  
Ordered State

Ge-films are evaporated under high vacuum conditions at 77°K. They are investigated either in the disordered state (before annealing at a higher temperature) or in the ordered state after annealing. The electric resistance R and the photoelectric work function Φ are measured before and after the influence of known amounts of carbon monoxide. R is plotted as a function of time and coverage n, Φ as a function of n. At 77°K an electronic interaction between the CO molecules and the Ge-film follows from an observed irreversible and reversible increase in R; Φ is not altered. The discussion by means of a band model shows that the CO molecules act as electron donors. At room temperature no interaction is found. Films precovered with oxygen show two simultaneous reactions during the adsorption of CO: a stronger adsorption on the spots precovered with oxygen and a weaker one on the bare Ge surface.

Direct evidence for charge ordering and electronic phase separation in BixSr1−xMnO3 at room temperature

2005 ◽  
Vol 370 (1-4) ◽  
pp. 172-177 ◽  
Author(s):  
A. Gupta ◽  
S.B. Samanta ◽  
V.P.S. Awana ◽  
H. Kishan ◽  
A.M. Awasthi ◽  
...  
Keyword(s):  
Phase Separation ◽  
Room Temperature ◽  
Direct Evidence ◽  
Charge Ordering ◽  
Electronic Phase Separation ◽  
Electronic Phase

Continuous flow vortex fluidic production of biodiesel

RSC Advances ◽  
2014 ◽  
Vol 4 (91) ◽  
pp. 49850-49854 ◽  
Author(s):  
Joshua Britton ◽  
Colin L. Raston
Keyword(s):  
Phase Separation ◽  
Sunflower Oil ◽  
Continuous Flow ◽  
Room Temperature ◽  
Flow Vortex ◽  
Spontaneous Phase

Vortex fluidic synthesis of biodiesel from sunflower oil under continuous flow at room temperature, with spontaneous phase separation.

Slow Decay of Reflection High Energy Electron Diffraction Oscillations in Cal1-xMgxF2

1996 ◽  
Vol 441 ◽  
Author(s):  
Mitsuhiro Kushibe ◽  
Yuriy V. Shusterman ◽  
Nikolai L. Yakovlev ◽  
Leo J. Schowalter
Keyword(s):  
Phase Separation ◽  
Electron Diffraction ◽  
Lattice Constant ◽  
Room Temperature ◽  
High Energy ◽  
Energy Electron ◽  
Scanning Tunneling ◽  
High Energy Electron ◽  
Tunneling Microscopy ◽  
Slow Decay

AbstractMagnesium is incorporated into the growth of Ca1-xMgxF2 to reduce the lattice constant of fluorite (CaF2) which is 0.6% larger than that of Si at room temperature. When grown epitaxially on Si(111) substrates at 300°C, the lattice constant of the alloy became smaller than that of Si by 1.5% when the Mg concentration was around 20%. At higher Mg concentrations, the lattice constant did not decrease any further. This invariability of the lattice constant was caused by a phase separation of the Ca1-xMgxF2 layer into a Mg-rich region and a Mg-deficient region. When the growth temperature was increased, the critical Mg concentration for the phase separation became smaller. When Ca1-xMgxF2 was grown on vicinal Si(111) substrates, the reflection high energy electron diffraction (RHEED) intensity oscillations reflected no change in the composition, suggesting segregation of a Mg-rich phase along the steps. Nevertheless, the oscillations in the intensity of the specular spot for Ca1-xMgxF2 lasted longer than those observed for pure CaF2, suggesting a flatter surface for the alloy. Scanning tunneling microscopy (STM) observations support this model.

scholarly journals Chasing Aqueous Biphasic Systems from Simple Salts by Exploring the LiTFSI

2018 ◽  
Author(s):  
Nicolas Dubouis ◽  
Chanbum Park ◽  
Michael Deschamps ◽  
Soufiane Abdelghani-Idrissi ◽  
Matej Kanduč ◽  
...  
Keyword(s):  
Phase Separation ◽  
Room Temperature ◽  
Fundamental Question ◽  
Aqueous Biphasic Systems ◽  
Wide Range ◽  
Battery Systems ◽  
Aqueous Biphasic ◽  
Biphasic Systems ◽  
And Control ◽  
Liquid Liquid Phase Separation

<i>Aqueous Biphasic Systems (ABS), in which two aqueous phases with different compositions coexist as separate liquids, have first been reported over a century ago with polymer solutions. Recent observations of ABS forming from concentrated mixtures of inorganic salts and ionic liquids raise the fundamental question of how "different" the components of such mixtures should be for a liquid-liquid phase separation to occur. Here we show that even two monovalent salts sharing a common cation (lithium) but with different anions, namely LiCl and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), may result in the formation of ABSs over a wide range of compositions at room temperature. Using a combination of experimental techniques and molecular simulations, we analyze the coexistence diagram and the mechanism driving the phase separation, arising from the different anion sizes. The understanding and control of ABS may provide new avenues for aqueous-based battery systems. </i>

scholarly journals Chasing Aqueous Biphasic Systems from simple salts by exploring the LiTFSI/LiCl/H2O phase diagram

2019 ◽  
Author(s):  
Nicolas Dubouis ◽  
Chanbum Park ◽  
Michael Deschamps ◽  
Soufiane Abdelghani-Idrissi ◽  
Matej Kanduč ◽  
...  
Keyword(s):  
Phase Separation ◽  
Room Temperature ◽  
Fundamental Question ◽  
Aqueous Biphasic Systems ◽  
Wide Range ◽  
Battery Systems ◽  
Aqueous Biphasic ◽  
Biphasic Systems ◽  
And Control ◽  
Liquid Liquid Phase Separation

<i>Aqueous Biphasic Systems (ABS), in which two aqueous phases with different compositions coexist as separate liquids, have first been reported over a century ago with polymer solutions. Recent observations of ABS forming from concentrated mixtures of inorganic salts and ionic liquids raise the fundamental question of how "different" the components of such mixtures should be for a liquid-liquid phase separation to occur. Here we show that even two monovalent salts sharing a common cation (lithium) but with different anions, namely LiCl and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), may result in the formation of ABSs over a wide range of compositions at room temperature. Using a combination of experimental techniques and molecular simulations, we analyze the coexistence diagram and the mechanism driving the phase separation, arising from the different anion sizes. The understanding and control of ABS may provide new avenues for aqueous-based battery systems. </i>

Sign in / Sign up

Export Citation Format

Share Document