Theoretical Analysis of Phase-Transition Temperature of Hydrogen-Bonded Dielectric Materials Induced by H/D Isotope Effect

2013 ◽  
pp. 303-329
Author(s):  
Takayoshi Ishimoto ◽  
Masanori Tachikawa
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Theoretical Analysis ◽  
Isotope Effect ◽  
Phase Transition Temperature ◽  
Dielectric Materials ◽  
Hydrogen Bonded

Theoretical Study on the Phase Transition and the H/D Isotope Effect of Squaric Acid

2012 ◽  
Vol 189 ◽  
pp. 169-177 ◽  
Author(s):  
Takayoshi Ishimoto ◽  
Masanori Tachikawa
Keyword(s):  
Phase Transition ◽  
Isotope Effect ◽  
First Principles ◽  
Dielectric Material ◽  
Dielectric Materials ◽  
First Principles Calculation ◽  
Squaric Acid ◽  
Teller Distortion ◽  
Unit Structure ◽  
Hydrogen Bonded

We investigated the phase transition and the isotope effect in squaric acid (H2C4O4, abbreviated H2SQ), a hydrogen-bonded dielectric material. Using first-principles calculation, we found that Jahn-Teller distortion of the unit structure (C4H4O4) was the major driving force for the phase transition in the H2SQ crystal. In order to elucidate the isotope effect on the phase transition in deuterated squaric acid (D2SQ), we employed the multi-component molecular orbital (MC_MO) method, which directly takes into account the quantum effects of protons and deuterons. Using this model, we successfully predicted the difference between the phase transition temperature of H2SQ and that of D2SQ to be 192K, which is in reasonable agreement with the experimental value of 145 K. We found that the isotope effect in the H2SQ/D2SQ system was based more on shrinking distribution of the deuteron wave rather than that of the proton wave. When the MC_MO method was coupled with adequate cluster models, first-principles calculations were effective to determining the origin of the phase transition and the H/D isotope effect in hydrogen-bonded dielectric materials.

A prominent dielectric material with extremely high-temperature and reversible phase transition in the high thermally stable perovskite-like architecture

2015 ◽  
Vol 3 (24) ◽  
pp. 6350-6358 ◽  
Author(s):  
Fang-Fang Wang ◽  
Cheng Chen ◽  
Yi Zhang ◽  
Heng-Yun Ye ◽  
Qiong Ye ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Dielectric Material ◽  
Dielectric Materials ◽  
Dielectric Anomaly ◽  
Thermally Stable ◽  
Reversible Phase Transition ◽  
Reversible Phase

A perovskite-like dielectric material (C3N2H5)·[Mn(HCOO)3] (1), exhibiting remarkably high Tc (phase transition temperature) and pronounced dielectric anomaly, can be considered as a model of novel extremely high-temperature dielectric materials.

The structure of membranes and membrane proteins embedded in amorphous ice

1992 ◽  
Vol 50 (1) ◽  
pp. 432-433
Author(s):  
Uwe Lücken ◽  
Joachim Jäger
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Membrane Proteins ◽  
Phase Transition Temperature ◽  
Lipid Vesicles ◽  
Freezing Stress ◽  
Amorphous Ice ◽  
Different Temperatures ◽  
Band Pass ◽  
Lipid Polymorphism

TEM imaging of frozen-hydrated lipid vesicles has been done by several groups Thermotrophic and lyotrophic polymorphism has been reported. By using image processing, computer simulation and tilt experiments, we tried to learn about the influence of freezing-stress and defocus artifacts on the lipid polymorphism and fine structure of the bilayer profile. We show integrated membrane proteins do modulate the bilayer structure and the morphology of the vesicles.Phase transitions of DMPC vesicles were visualized after freezing under equilibrium conditions at different temperatures in a controlled-environment vitrification system. Below the main phase transition temperature of 24°C (Fig. 1), vesicles show a facetted appearance due to the quasicrystalline areas. A gradual increase in temperature leads to melting processes with different morphology in the bilayer profile. Far above the phase transition temperature the bilayer profile is still present. In the band-pass-filtered images (Fig. 2) no significant change in the width of the bilayer profile is visible.

Molecular Ordering of a Nematogen at Phase Transition Temperature - A Theoretical Study

2002 ◽  
Vol 75 (4-5) ◽  
pp. 413-421
Author(s):  
Durga Prasad Ojha ◽  
Devesh Kumar ◽  
V.G.K.M. Pisipati
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Theoretical Study ◽  
Molecular Ordering

scholarly journals Study of physical properties of a ferrimagnetic spinel Cu1.5Mn1.5O4: spin dynamics, magnetocaloric effect and critical behavior

RSC Advances ◽  
2021 ◽  
Vol 11 (41) ◽  
pp. 25664-25676
Author(s):  
Abir Hadded ◽  
Jalel Massoudi ◽  
Sirine Gharbi ◽  
Essebti Dhahri ◽  
A. Tozri ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Physical Properties ◽  
Magnetocaloric Effect ◽  
Phase Transition Temperature ◽  
Magnetic Phase Transition ◽  
Critical Behavior ◽  
Magnetic Phase ◽  
Spin Dynamics ◽  
Critical Behaviour

The present work reports a detailed study of the spin dynamics, magnetocaloric effect and critical behaviour near the magnetic phase transition temperature, of a ferrimagnetic spinel Cu1.5Mn1.5O4.

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