Ab INITIO CALCULATION OF THE LixCoO2 PHASE DIAGRAM

1997 ◽  
Vol 496 ◽  
Author(s):  
Anton Van Der Ven ◽  
Mehmet K Aydinol ◽  
Gerbrand Ceder
Keyword(s):  
Phase Diagram ◽  
First Principles ◽  
Driving Forces ◽  
Intercalation Compound ◽  
Phase Region ◽  
Metal Insulator Transition ◽  
Two Phase ◽  
Metal Insulator ◽  
The Past ◽  
Li Batteries

ABSTRACTThe electrochemical properties of the layered intercalation compound LiCoO2 used as a cathode in Li batteries have been investigated extensively in the past 15 years. Despite this research, little is known about the nature and thermodynamic driving forces for the phase transformations that occur as the Li concentration is varied. In this work, the phase diagram of LixCoO2 is calculated from first principles for x ranging from 0 to 1. Our calculations indicate that there is a tendency for Li ordering at x = 1/2 in agreement with experiment [1]. At low Li concentration, we find that a staged compound is stable in which the Li ions selectively segregate to every other Li plane leaving the remaining Li planes vacant. We find that the two phase region observed at high Li concentration is not due to Li ordering and speculate that it is driven by a metal-insulator transition which occurs at concentrations slightly below x < 1.

Orbital change manipulation metal–insulator transition temperature in W-doped VO2

2015 ◽  
Vol 17 (17) ◽  
pp. 11638-11646 ◽  
Author(s):  
Xinfeng He ◽  
Yijie Zeng ◽  
Xiaofeng Xu ◽  
Congcong Gu ◽  
Fei Chen ◽  
...  
Keyword(s):  
Phase Transition ◽  
Infrared Spectroscopy ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
First Principles ◽  
Insulator Transition ◽  
First Principles Calculations ◽  
Orbital Structure ◽  
Metal Insulator Transition ◽  
Metal Insulator

Using ultraviolet-infrared spectroscopy and first principles calculations, it is revealed that changes in the orbital structure can regulate the W-doped VO2 phase transition temperature.

Rheological and structural studies on heat-induced gelation of concentrated skim milk

1995 ◽  
Vol 62 (2) ◽  
pp. 257-267 ◽  
Author(s):  
Atsumi Tobitani ◽  
Haruyoshi Yamamoto ◽  
Toshiaki Shioya ◽  
Simon B. Ross-Murphy
Keyword(s):  
Phase Diagram ◽  
Laser Light ◽  
Skim Milk ◽  
Phase Region ◽  
Polymer Physics ◽  
Phase Behaviour ◽  
Two Phase ◽  
Effects Of Ph ◽  
Higher Temperature ◽  
Temperature Side

SUMMARYHeat-induced gelation of milk was studied using both rheological and structural techniques. The sample was a conventional skim milk, concentrated with an ultrafiltration membrane, which formed gels when heated at appropriate pH. We investigated some factors that are considered to affect the gelation, such as concentration, pH and rennet treatment. The gelation process was monitored with a high precision oscillatory shear rheometer and the structure of gels was evaluated with quasi-elastic laser light scattering. From these results the gelation and phase separation behaviour were determined. By combining the results for different concentrations a phase diagram was obtained, which indicated that skim milk had a two-phase region on the higher temperature side. The effects of pH and rennet treatment were also evaluated with the aid of this phase diagram. The results were discussed on the basis of concepts of the phase behaviour of polymers, which were successfully developed in polymer physics.

Strain control of orbital polarization and correlated metal-insulator transition in La2CoMnO6 from first principles

2011 ◽  
Vol 99 (20) ◽  
pp. 202110 ◽  
Author(s):  
Shuhui Lv ◽  
Hongping Li ◽  
Zhongchang Wang ◽  
Lin Han ◽  
Yao Liu ◽  
...  
Keyword(s):  
First Principles ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Strain Control ◽  
Metal Insulator

scholarly journals Identification of a monoclinic metallic state in VO2 from a modified first-principles approach

2019 ◽  
Vol 33 (12) ◽  
pp. 1950148
Author(s):  
Yongcheng Liang ◽  
Ping Qin ◽  
Zhiyong Liang ◽  
Lizhen Zhang ◽  
Xun Yuan ◽  
...  
Keyword(s):  
First Principles ◽  
Lattice Distortion ◽  
Insulator Transition ◽  
Metallic State ◽  
Strongly Correlated ◽  
Electron Systems ◽  
First Principles Calculations ◽  
Monoclinic Structure ◽  
Metal Insulator Transition ◽  
Metal Insulator

Metal-insulator transition (MIT) underlies many remarkable and technologically important phenomena in VO2. Even though its monoclinic structure had before been the reserve of the insulating state, recent experiments have observed an unexpected monoclinic metallic state. Here, we use a modified approach combining first-principles calculations with orbital-biased potentials to reproduce the correct stability ordering and electronic structures of different phases of VO2. We identify a ferromagnetic monoclinic metal that is likely to be the experimentally observed mysterious metastable state. Furthermore, the calculations show that an isostructural insulator-metal electronic transition is followed by the lattice distortion from the monoclinic structure to the rutile one. These results not only explain the experimental observations of the monoclinic metallic state and the decoupled structural and electronic transitions of VO2, but also provide a useful understanding for the metal-insulator transition in other strongly correlated d electron systems.

High-pressureV51NMR study of the magnetic phase diagram and metal-insulator transition in quasi-one-dimensionalβ-Na0.33V2O5

2009 ◽  
Vol 79 (8) ◽  
Author(s):  
Taisuke Suzuki ◽  
Ichihiro Yamauchi ◽  
Yasuhiro Shimizu ◽  
Masayuki Itoh ◽  
Nao Takeshita ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Magnetic Phase ◽  
Magnetic Phase Diagram ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator

scholarly journals Continuous Localisation - Delocalisation Transition at Intermediate Electron Densities

1999 ◽  
Vol 52 (5) ◽  
pp. 779
Author(s):  
D. Neilson ◽  
J. S. Thakur
Keyword(s):  
Phase Diagram ◽  
Temperature Phase ◽  
Electron Correlations ◽  
Zero Temperature ◽  
Semiconductor Substrate ◽  
Electron Densities ◽  
Metal Insulator Transition ◽  
Continuous Transition ◽  
Metal Insulator ◽  
Temperature Phase Diagram

We find in 2D electron layers in quantum transistors that the interplay between the electron correlations and their interactions with defects in the semiconductor substrate generates a continuous localisation–delocalisation transition for intermediate electron densities (5 ≲ rs ≲ 9). We distinguish this transition from the discontinuous metal–insulator transition which is observed at lower electron densities (rs ≳ 10). The approach we use is based on the behaviour of electrons at low densities. We take into account the interactions between electrons and also their interactions with disorder. We determine a zero temperature phase diagram of localised and delocalised states as a function of electron and impurity densities. The phase boundary of the continuous transition is determined by the localisation length of the electrons.

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