Strong coupling between proton and phonon in KDP

Pak, K. N.

doi:10.1002/pssb.2220600125

Cited by 14 publications

(7 citation statements)

References 22 publications

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“…In the paraelectric phase, the dielectric constant of order-disorder type ferroelectric follows the Curie-Weiss law with C=10 3 K, when temperature is measured in K. The dielectric constant exhibits no relaxation at higher microwave frequency (35GHz). The Curie-Weiss behavior of tangent loss in KDP, shows that this contribution is due to the temperature independent term α in Equation 13. This suggests that imperfections cause damping.…”

Section: Comparison With Experiments and Discussionmentioning

confidence: 97%

“…The temperature dependence of microwave loss tangent in KDP is empirically represented by Equation 13. This dependence can be explained in terms of slowing down of a relaxational mode.…”

Section: Comparison With Experiments and Discussionmentioning

confidence: 99%

“…At first, Pak 13 employed Green's function methods in the order-disorder type ferroelectrics, who however, did not consider the anharmonic interactions. The phonon anharmonic interactions have been found very important in explaining dielectric, thermal and scattering properties of solids by many authors 9,14,15 in the past.…”

Section: Introductionmentioning

confidence: 99%

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Soft Mode Dynamics of Order-Disorder Type Crystals

2017

Chem Sci Trans

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Abstract:The soft mode dynamics and related properties of order-disorder type crystals have been studied. The phonon width and shift have been calculated, which lead to the renormalization of the relaxation soft-mode. The dielectric properties are directly related to the relaxational soft mode behavior of stochastic motion of H 2 PO 4 groups in order-disorder (KDP-system) crystals. The analysis of the temperature dependence of microwave loss tangent and dielectric constant explain the experimental results.

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Section: Comparison With Experiments and Discussionmentioning

confidence: 97%

“…The temperature dependence of microwave loss tangent in KDP is empirically represented by Equation 13. This dependence can be explained in terms of slowing down of a relaxational mode.…”

Section: Comparison With Experiments and Discussionmentioning

confidence: 99%

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Soft Mode Dynamics of Order-Disorder Type Crystals

2017

Chem Sci Trans

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“…Higher order Green's functions are evaluated without any decoupling and using renormalized Hamiltonian. Putting the evaluated value of higher order Green's function in (19), one gets…”

Section: Collective Phonon Half Width and Mode Frequency Shiftmentioning

confidence: 99%

“…At first, Pak [19] employed Green's function methods in the order-disorder type ferroelectrics and, however, did not consider the anharmonic interactions. The phonon anharmonic interactions have been found very important in explaining dielectric, thermal, and scattering properties of solids by many authors [6-9, 20, 21] in the past.…”

Section: Introductionmentioning

confidence: 99%

Study of Dielectric Properties and Ultrasonic Attenuation in KDP-Type Ferroelectrics

Bist

Panwar

2016

Physics Research International

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The soft mode dynamical model has been used to study dielectric properties and ultrasonic attenuation in KDP-type ferroelectric crystals. The model Hamiltonian proposed by Blinc and Zeks has been modified by considering lattice anharmonicity up to fourth-order. The correlations appearing in the dynamical equation have been evaluated using double-time thermal retarded Green’s functions method and Dyson’s equation. Without any decoupling, the higher order correlations, appearing in the dynamical equation, have been evaluated using the renormalized Hamiltonian. The expressions for collective frequencies, width, dielectric constant, ultrasonic attenuation, and tangent loss have been calculated. The dielectric properties and ultrasonic attenuation strongly depend on the relaxational mode behavior of stochastic motion of H2PO4group in KDP-type ferroelectrics. By fitting model values of physical quantities, the temperature dependence ofSqzandSqxfor different value of four-body coupling coefficient and dielectric constant and loss tangent has been calculated. The calculated and observed results have been found in good agreement.

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A Study on Effective Charge in the Dipole Theory of Ferroelectrics

Pak

Yokoyama

Kinase

1974

Physica Status Solidi (b)

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The effective charge used in dipole theory of ferroelectrics has been investigated theoretically. Particular emphasis is placed on its temperature dependence. Employing the concept of the statistical theory of ferroelectricity, it is shown that in the dipole theory the effective charge corresponds to the temperature, and the relation between them has been established in a statistical way within the framework of dipole theory. The temperature dependence of the effective charge has been determined in detail by carrying out the numerical calculations and the results obtained have been discussed. As a result, it is found that in the ferroelectric phase the effective charge depends strongly on temperature as the long-range dipole interaction becomes large and this inclination is more remarkable in the vicinity of the transition point, whereas in the paraelectric phase the effective charge is nearly independent of temperature over a wide range of it, except near the transition point.Es wird die in der Dipoltheorie der Ferroelektrika benutzte effektive Ladung theoretisch untersucht. Besonderes Gewicht wird auf ihre Temperaturabhangigkeit gelegt. Mit dem Konzept der statistischen Theorie der Ferroelektrizitat wird gezeigt, daD in der Dipoltheorie die effektive Ladung der Temperatur entspricht, und es wird die Beziehung zwischen ihnen in einer statistischen Weise im Rahmen der Dipoltheorie aufgestellt. Die Temperaturabhangigkeit der effektiven Ladung wird ausfiihrlich durch numerische Rechnungen bestimmt, und die erhaltenen Ergebnisse werden diskutiert. Als Ergebnis wird gefunden, daD in der ferroelektrischen Phase die effektive Ladung stark von der Temperatur abhangt, da die langreichweitige Dipolwechselwirkung groD wird und dieser EinfluD in der Niihe des tfbergangspunktes starker ist, wahrend in der paraelektrischen Phase die effektive Ladung nahezu unabhingig von der Temperatur in einem grol3en Bereich mit Ausnahme der Nahe des tfbergangspunktes ist.

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Strong coupling between proton and phonon in KDP

Cited by 14 publications

References 22 publications

Soft Mode Dynamics of Order-Disorder Type Crystals

Soft Mode Dynamics of Order-Disorder Type Crystals

Study of Dielectric Properties and Ultrasonic Attenuation in KDP-Type Ferroelectrics

A Study on Effective Charge in the Dipole Theory of Ferroelectrics

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