14N NQR and proton NMR study of ferroelectric phase transition and proton exchange in organic ferroelectric (H2-TPPZ)(Hca)2

2010 ◽  
Vol 12 (13) ◽  
pp. 3254 ◽  
Author(s):  
Janez Seliger ◽  
Veselko Žagar ◽  
Tetsuo Asaji ◽  
Yumi Hasegawa
Keyword(s):  
Phase Transition ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Proton Nmr ◽  
Proton Exchange ◽  
Nmr Study

207Pb NMR study of the ferroelectric phase transition in PbHPO4

1986 ◽  
Vol 19 (20) ◽  
pp. 3925-3932 ◽  
Author(s):  
B Topic ◽  
U Haeberlen ◽  
R Blinc ◽  
H Arend
Keyword(s):  
Phase Transition ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Nmr Study

2D NMR Study near the Ferroelectric Phase Transition of TSCC

1987 ◽  
Vol 139 (2) ◽  
pp. 609-617 ◽  
Author(s):  
F. Engelke ◽  
D. Michel ◽  
W. Windsch ◽  
J. Petersson
Keyword(s):  
Phase Transition ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
2D Nmr ◽  
Nmr Study

31P NMR study of the ferroelectric phase transition in PbHPO4

1989 ◽  
Vol 1 (32) ◽  
pp. 5489-5496 ◽  
Author(s):  
F Ermark ◽  
B Topic ◽  
U Haeberlen ◽  
R Blinc
Keyword(s):  
Phase Transition ◽  
Ferroelectric Phase Transition ◽  
31P Nmr ◽  
Ferroelectric Phase ◽  
Nmr Study

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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