scholarly journals Особенности МДП-структур на основе изолирующих пленок PbSnTe : In с составом вблизи инверсии зон, обусловленные их сегнетоэлектрическими свойствами

2020 ◽  
Vol 54 (10) ◽  
pp. 1122
Author(s):  
А.Э. Климов ◽  
А.Н. Акимов ◽  
И.О. Ахундов ◽  
В.А. Голяшов ◽  
Д.В. Горшков ◽  
...  
Keyword(s):  
Phase Transition ◽  
Molecular Beam Epitaxy ◽  
Curie Temperature ◽  
Ferroelectric Phase Transition ◽  
Molecular Beam ◽  
Ferroelectric Phase ◽  
Band Inversion ◽  
Mis Structures

The characteristics of MIS structures based on insulating PbSnTe:In films with compositions in the vicinity of a band inversion grown by molecular beam epitaxy (MBE) were studied. It has been shown that a number of their features can be caused by a ferroelectric phase transition with a Curie temperature in the range T ≈ 15–20 K.

Ferroelectricity of trimethylammonium bromide below room temperature

2020 ◽  
Vol 8 (17) ◽  
pp. 5868-5872 ◽  
Author(s):  
Zhangran Gao ◽  
Yuying Wu ◽  
Zheng Tang ◽  
Xiaofan Sun ◽  
Zixin Yang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Curie Temperature ◽  
Ferroelectric Phase Transition ◽  
Room Temperature ◽  
Ferroelectric Phase ◽  
First Order

Ferroelectricity of trimethylammonium bromide was discovered near room temperature, which undergoes a first-order paraelectric–ferroelectric phase transition at the Curie temperature around 286 K.

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.

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