Mn2+EPR study of phase transitions in dicalcium lead propionateCa2Pb(C2H5COO)6: Determination of critical exponent below the ferroelectric phase transition and comparison with EPR studies onCa2Ba(C2H5COO)6andCa2Sr(C2H5COO)6

1989 ◽  
Vol 39 (4) ◽  
pp. 2041-2050 ◽  
Author(s):  
Sushil K. Misra ◽  
Stanislaw Jerzak
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Critical Exponent ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase

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.

Phase Transitions in Nanoscale Ferroelectric Structures

MRS Bulletin ◽  
2009 ◽  
Vol 34 (11) ◽  
pp. 832-837 ◽  
Author(s):  
S.K. Streiffer ◽  
D.D. Fong
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Ferroelectric Phase Transition ◽  
Recent Progress ◽  
Ferroelectric Phase ◽  
Model Systems ◽  
Materials Processing ◽  
Phase Transition Behavior ◽  
Great Progress ◽  
The Common

AbstractOver decades of effort, investigations of the intrinsic phase transition behavior of nanoscale ferroelectric structures have been greatly complicated by materials processing variations and by the common and uncontrolled occurrence of spacecharge, which interacts directly with the polarization and can obscure fundamental behavior. These challenges have largely been overcome, and great progress in understanding the details of this class of phase transitions has been made, largely based on advances in the growth of high-quality, epitaxial ferroelectric films and in the theory and simulation of ferroelectricity. Here we will discuss recent progress in understanding the ferroelectric phase transition in a particular class of model systems: nanoscale perovskite thin-film heterostructures. The outlook for ferroelectric technology based on these results is promising, and extensions to laterally confined nanostructures will be described.

Exafs Studies of Semiconductors

1986 ◽  
Vol 77 ◽  
Author(s):  
Bruce A. Bunker
Keyword(s):  
Phase Transition ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Exafs Spectroscopy ◽  
Nondestructive Measurement ◽  
Bond Lengths ◽  
Fe Impurities

ABSTRACTRecent results from EXAFS spectroscopy are discussed, including (i) the determination of the site and local bond lengths of Fe impurities implanted into Si, (ii) the determination of the ferroelectric phase transition in Pb1−x Gex Te as order-disorder rather than displacive, and (iii) the nondestructive measurement of Aℓ diffusion into GaAs at an Aℓ/GaAs Interface.

Ferroelectric Phase Transition Investigated by Thermal Analysis and Raman Scattering in SrBi2Ta2O9 Nanoparticles

2007 ◽  
Vol 121-123 ◽  
pp. 843-846 ◽  
Author(s):  
Hua Ke ◽  
De Chang Jia ◽  
Wen Wang ◽  
Yu Zhou
Keyword(s):  
Phase Transition ◽  
Thermal Analysis ◽  
Particle Size ◽  
Phase Transitions ◽  
Size Effect ◽  
Raman Spectra ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Intermediate Phase ◽  
Transition Sequence

Thermal analysis and Raman spectra were carried out in SrBi2Ta2O9 (SBT) nanoparticles to investigate phase transitions. Two anomalies have been observed in temperature dependence of specific heat for SBT nanoparticles. Under the combination with Raman spectra, it indicates that there exists a new ferroelectric intermediate phase in the phase-transition sequence. So we can conclude that the phase-transition sequence in SBT nanoparticles should be ferroelectric-ferroelectric-paraelectric. Moreover, the size effect was discussed in consideration of inner compressive stress in nanoparticles for this special transition behavior. The calculated results show that the SBT nanoparticles keep the ferroelectricity until the particle size is decreased to 4.2 nm.

1D metal-oxalates H2DABCO[M(C2O4)2]·3H2O (M(ii): Co, Mg, Zn): phase transitions and magnetic, dielectric, and phonon properties

2020 ◽  
Vol 8 (18) ◽  
pp. 6254-6263 ◽  
Author(s):  
Katarzyna Pasińska ◽  
Aneta Ciupa ◽  
Adam Pikul ◽  
Anna Gągor ◽  
Adam Pietraszko ◽  
...  
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Long Range ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Antiferromagnetic Ordering ◽  
Magnetic Dielectric ◽  
Phonon Properties

We report the first example of 1D multiferroic homometallic oxalate, which exhibits ferroelectric phase transition around 219 K and a long-range antiferromagnetic ordering below 4 K.

Dielectric Study of the Ferroelectric Phase Transition in DMAGaS Crystal

1998 ◽  
Vol 53 (3-4) ◽  
pp. 105-111 ◽  
Author(s):  
R. Tchukvinskyi ◽  
R. Cach ◽  
Z. Czapla
Keyword(s):  
Phase Transition ◽  
Electric Field ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Paraelectric Phase ◽  
Dielectric Study ◽  
Electric Permittivity ◽  
First Order ◽  
Dc Electric Field

Abstract Electric permittivity measurments as functions of temperature at constant dc electric field and as functions of the dc electric field at constant temperatures in the paraelectric phase have been performed for DMAGaS crystal. The changes of the permittivity maximum with the electric field intensity evidence the first-order character of the ferroelectric phase transition at Tc1. The field dependence of the permittivity ε(E) in the paraelectric phase is discussed, using the classical electric equation of state. A method for the determination of the corresponding coefficients is proposed. The obtained B and C coefficients, together with double hysteresis loop observed above Tc1 prove the first-order character of the ferroelectric phase transition in DMAGaS crystal.

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