Effect of donor doping in B sites on the electrocaloric effect of BaTi1−xNbxO3 ceramics

RSC Advances ◽  
2015 ◽  
Vol 5 (88) ◽  
pp. 71873-71877 ◽  
Author(s):  
Yang Bai ◽  
Xi Han ◽  
Li-Jie Qiao
Keyword(s):  
Phase Transition ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Electrocaloric Effect ◽  
Donor Doping ◽  
Temperature Window ◽  
Lower Temperature

The donor doping of Nb5+ for Ti4+ in the B sites of BaTiO3 rapidly shifts the ferroelectric phase transition to a lower temperature and diffuses it, so that the electrocaloric ΔTmax gradually reduces and the temperature window becomes much wider.

scholarly journals Influence of KF substitution on the ferroelectric phase transition of lead titanate single crystals studied by Brillouin light scattering

2015 ◽  
Vol 05 (02) ◽  
pp. 1550011
Author(s):  
Seonhyeop Shin ◽  
Jae-Hyeon Ko ◽  
Shinya Tsukada ◽  
Yukikuni Akishige ◽  
Krystian Roleder ◽  
...  
Keyword(s):  
Phase Transition ◽  
Light Scattering ◽  
Lead Titanate ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Paraelectric Phase ◽  
Dielectric Measurements ◽  
Brillouin Light Scattering ◽  
Acoustic Damping ◽  
Lower Temperature

The elastic properties of KF-substituted perovskite lead titanate ( PbTiO 3) were investigated by dielectric measurements and Brillouin light scattering. The ferroelectric phase transition occurred at substantially lower temperature due to KF substitution, which was attributed to the modification of the covalency in Pb – O and Ti – O bonds. The longitudinal acoustic (LA) mode of KF-substituted PbTiO 3 showed a frequency softening in the paraelectric phase, which was accompanied by increasing acoustic damping. This indicated that polarization fluctuations responsible for the acoustic anomalies were enhanced by KF substitution.

Effect of electric field orientation on ferroelectric phase transition and electrocaloric effect

2020 ◽  
Vol 191 ◽  
pp. 13-23 ◽  
Author(s):  
Zhonghua Li ◽  
Jianting Li ◽  
Hong-Hui Wu ◽  
Junjie Li ◽  
Shihan Wang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Electric Field ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Electrocaloric Effect ◽  
Field Orientation

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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