Temperature dependence of soft mode frequency and its damping in various ferroelectrics

In this review the dielectric properties of relaxor ferroelectrics are discussed and compared with the properties of normal dielectrics and ferroelectrics. We try to draw a general picture of dielectric relaxation starting from a textbook review of the underlying concepts and pay attention to common behavior of relaxors rather than to the features observed in specific materials. We hope that this general approach is beneficial to those physicists, chemists, material scientists and device engineers who deal with relaxors. Based on the analysis of dielectric properties, a comprehensive definition of relaxors is proposed: relaxors are defined as ferroelectrics in which the maximum in the temperature dependence of static susceptibility occurs within the temperature range of dielectric relaxation, but does not coincide with the temperature of singularity of relaxation time or soft mode frequency.

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Phase Transition Study of Thermal Dependence of Soft Mode Frequency, Dielectric Constant and Dielectric Tangent Loss Properties in CsH2PO4 (CDP) and CsD2PO4 (DCDP) Crystals

Journal of Low Temperature Physics ◽

10.1007/s10909-021-02589-5 ◽

2021 ◽

Author(s):

Muzaffar Iqbal Khan ◽

Trilok Chandra Upadhyay

Keyword(s):

Phase Transition ◽

Dielectric Constant ◽

Soft Mode ◽

Mode Frequency ◽

Tangent Loss ◽

Thermal Dependence ◽

Dielectric Tangent Loss ◽

Transition Study

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Temperature dependence of the IR mode frequency calculated from the volume data for DMNaFE

Ferroelectrics ◽

10.1080/00150193.2019.1658049 ◽

2019 ◽

Vol 551 (1) ◽

pp. 229-234 ◽

Cited By ~ 1

Author(s):

G. Algül ◽

Y. Enginer ◽

H. Yurtseven

Keyword(s):

Temperature Dependence ◽

Mode Frequency ◽

Volume Data

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The temperature dependence of the photoinduced soft mode in Sn2P2S6 crystal

International Journal of Modern Physics B ◽

10.1142/s0217979219500619 ◽

2019 ◽

Vol 33 (08) ◽

pp. 1950061

Author(s):

K. A. Brekhov ◽

N. A. Ilyin ◽

E. D. Mishina ◽

P. A. Prudkovskii ◽

G. Kh. Kitaeva

Keyword(s):

Phase Transition ◽

Femtosecond Laser ◽

Curie Temperature ◽

Temperature Dependence ◽

Oscillation Frequency ◽

Phonon Mode ◽

Soft Mode ◽

Laser Pulses ◽

Femtosecond Laser Pulses ◽

Curie Temperature Tc

In this paper, we present the results of the temperature dependence studies of the photoinduced phonon mode which appears in a ferroelectric-semiconductor Sn2P2S6 (SPS) crystal under the influence of femtosecond laser pulses. We show that its behavior reminds the soft mode one near the phase transition. However, the observed decrease in the oscillation frequency in the vicinity of Curie temperature Tc is much weaker than previously reported. This can be explained by the shadowing of the pure soft mode by its interaction with other photoinduced modes.

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Temperature dependence of the magnetic excitations in the modified triangular induced moment antiferromagnet RbFeBr3 at the soft mode point (abstract)

Journal of Applied Physics ◽

10.1063/1.348819 ◽

1991 ◽

Vol 69 (8) ◽

pp. 6232-6232 ◽

Cited By ~ 5

Author(s):

D. Visser ◽

B. Dorner ◽

A. Harrison

Keyword(s):

Temperature Dependence ◽

Soft Mode ◽

Magnetic Excitations

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Theory of Ferroelectric Phase Transitions in Pure and Mixed Perovskites.

MRS Proceedings ◽

10.1557/proc-718-d8.6 ◽

2002 ◽

Vol 718 ◽

Cited By ~ 1

Author(s):

Yizhak Yacoby ◽

Yakov Girshberg

Keyword(s):

Temperature Dependence ◽

Ferroelectric Phase ◽

Paraelectric Phase ◽

Soft Mode ◽

Critical Concentration ◽

Comprehensive Model ◽

Coupling Constant ◽

Phonon Coupling ◽

Ferroelectric Phase Transitions ◽

Basic Experimental Data

AbstractWe present a comprehensive model of ferroelectricity in oxygen perovskite crystals that account quantitatively for both displacive like and order-disorder like properties. The model assumes that in the paraelectric phase, the system has a soft mode, interacting with spontaneous disordered off-center displacements. The resulting theory is shown to quantitatively explain the properties of two representative perovskites: KNbO3 and PbTiO3. We have further extended this theory to explain the properties of mixed incipient ferroelectrics with small concentrations of ferroelectricity inducing ions such as KTa1-xNbxO3. The model quantitatively reproduces the basic experimental data in the quantum regime: the temperature dependence of the inverse dielectric function, the impurity and temperature dependence of the renormalized soft mode vibrational frequency and the impurity concentration dependence of the transition temperature Tc. In particular we show that, the critical concentration for Tc=0 is determined by the ion tunneling frequency, the bare soft mode parameters and the pseudospin - phonon coupling constant.

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