Temperature dependence of electronic structure on the ferroelectric phase transition of BaTiO3

2021 ◽  
Vol 104 (23) ◽  
Author(s):  
Yasuhisa Tezuka ◽  
Shunsuke Nozawa ◽  
Nobuo Nakajima ◽  
Toshiaki Iwazumi
Keyword(s):  
Phase Transition ◽  
Electronic Structure ◽  
Temperature Dependence ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase

Origin of ferroelectric phase transition in SbSClxI1-x mixed crystals

2014 ◽  
Vol 28 (30) ◽  
pp. 1450209 ◽  
Author(s):  
A. Audzijonis ◽  
L. Žigas ◽  
R. Sereika ◽  
R. Žaltauskas
Keyword(s):  
Phase Transition ◽  
Free Energy ◽  
Temperature Dependence ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Harmonic Approximation ◽  
Temperature Dependent ◽  
Normal Coordinate ◽  
Unit Cell Parameters ◽  
Cell Parameters

The measurements of SbSCl x I 1-x(x = 0.2) temperature dependent capacitance were carried out. The temperature of ferroelectric phase transition TC ≈340 K was measured experimentally. TC of SbSCl x I 1-x was calculated theoretically in anharmonic and harmonic approximations. TC was calculated in anharmonic approximation using temperature dependence of mean potential energy of Sb atoms as a function of the soft B1u symmetry normal coordinate along c(z)-axis. Moreover, TC was calculated in harmonic approximation using temperature dependence of vibrational thermodynamic functions (Helmholc free energy). TC dependence from unit cell parameters a, b and from mixture composition x was carried out.

Modeling of High-Signal Electrostriction. II

1990 ◽  
Vol 45 (9-10) ◽  
pp. 1095-1101
Author(s):  
J von Cieminski
Keyword(s):  
Phase Transition ◽  
Temperature Dependence ◽  
Strain Field ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Second Order ◽  
Experimental Results ◽  
High Signal ◽  
Qualitative And Quantitative

Abstract The predictions obtained with a thermodynamical method are compared with experimental results. Several materials which pass a ferroelectric phase transition of first or second order are investigated. The predictions correspond well with the experimentaly determined qualitative and quantitative features as to the field and temperature dependence. Finally, extraordinary strain-field curves are predicted and proved.

Research of the Mechanism of Ferroelectric Phase Transition in Perovskite: Empty Orbital Model

2011 ◽  
Vol 130-134 ◽  
pp. 2809-2812
Author(s):  
Chao Fang ◽  
Liang Yan Chen
Keyword(s):  
Phase Transition ◽  
Curie Temperature ◽  
Temperature Dependence ◽  
Bond Energy ◽  
Equilibrium Position ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Point Of View ◽  
Repulsion Energy ◽  
The Impact

The empty orbital model in perovskite ATiO3-type (A=Mg, Ca, Sr and Ba) ferroelectrics with oxygen octahedra has been proposed. In this study, the impact of temperature on the bond energy of Ti-O has been discussed from the point of view of statistical thermodynamics, then the temperature dependence of equilibrium position of Ti ion has been calculated. The results show that because of the existence of empty orbital, with temperatrue decreasing the repulsion energy of Ti and O ions reduces and the Ti ion shift the equilibrium position in the cooling through the Curie temperature owing to Coulomb interaction. Ferroelectric phase transition in perovskite are successfully explained. Theoretical and experimental results for perovskite ATiO3-type ferroelectrics are compared and discussed.

scholarly journals The origin of the lattice thermal conductivity enhancement at the ferroelectric phase transition in GeTe

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Đorđe Dangić ◽  
Olle Hellman ◽  
Stephen Fahy ◽  
Ivana Savić
Keyword(s):  
Phase Transition ◽  
Thermal Conductivity ◽  
Phase Transitions ◽  
Thermoelectric Materials ◽  
Ferroelectric Phase Transition ◽  
Lattice Thermal Conductivity ◽  
Ferroelectric Phase ◽  
Structural Phase ◽  
High Symmetry ◽  
Structural Phase Transitions

AbstractThe proximity to structural phase transitions in IV-VI thermoelectric materials is one of the main reasons for their large phonon anharmonicity and intrinsically low lattice thermal conductivity κ. However, the κ of GeTe increases at the ferroelectric phase transition near 700 K. Using first-principles calculations with the temperature dependent effective potential method, we show that this rise in κ is the consequence of negative thermal expansion in the rhombohedral phase and increase in the phonon lifetimes in the high-symmetry phase. Strong anharmonicity near the phase transition induces non-Lorentzian shapes of the phonon power spectra. To account for these effects, we implement a method of calculating κ based on the Green-Kubo approach and find that the Boltzmann transport equation underestimates κ near the phase transition. Our findings elucidate the influence of structural phase transitions on κ and provide guidance for design of better thermoelectric materials.

Sign in / Sign up

Export Citation Format

Share Document