Raman linewidths calculated as a function of temperature in NaNO<sub>2</sub>

The Raman frequencies of the lattice modes (147 cm 1 and 207 cm 1 / are analyzed for the˛-ˇtran-sition in quartz according to a power-law formula with the critical exponent by using the experimental data. The temperature dependence of the Raman frequency is associated with the order parameter (polarization P ) for this transition in the quartz crystal. The damping constant of the lattice modes studied here is calculated using the Raman frequencies at various temperatures for the˛-ˇtransition in quartz (T c D 846 K) using the soft mode -hard mode and the energy fluctuation models. Our calculations for the damping constant (bandwidths) give an evidence that the lattice mode of the 147 cm 1 exhibits a soft mode behavior for the˛-ˇtransition in quartz.

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“…We have also used the above relations in our earlier studies for the ferroelectric crystals of sodium nitrate [20] and ammonium sulfate [21].…”

Section: Theorymentioning

confidence: 96%

“…The analysis of the observed Raman bandwidths has been performed near T c for the sodium nitrate [20] and ammonium sulfate [21] previously using Eq. (6).…”

Section: Theorymentioning

confidence: 99%

Calculation of the Raman Linewidths of Lattice Modes Close to the α-β Transition in Quartz

Lider

Yurtseven

2012

High Temperature Materials and Processes

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“…In our previous studies, we have calculated Brillouin frequency shifts in NaNO 2 [22,23] and we applied the spectroscopic modifications of Pippard relations [24][25][26] to this crystal. We have also calculated spontaneous polarization [27] and recently we have calculated Raman linewidths [28] as a function of temperature for NaNO 2 .…”

Section: Introductionmentioning

confidence: 99%

Temperature Dependence of the Spontaneous Polarization Near the Ferroelectric-Paraelectric Transition in NaNO2

Sarikaya

Yurtseven²

2013

High Temperature Materials and Processes

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The paraelectric-ferroelectric transition in NaNO 2 is studied using the Levanyuk-Sannikov and the mean field models which we have developed here. From both models, the temperature dependence of the spontaneous polarization is derived and is fitted to the experimental data from the literature.Our results show that both mean field models are adequate to describe the observed behaviour of the spontaneous polarization close to the paraelectric-ferroelectric transition in NaNO 2 . The two models are compared in regard to the transition mechanism in this crystal.

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“…The temperature dependence of the order parameter, using the mean field theory as given by Matsushita [17], has also been calculated for ammonium halides in our previous study [22]. Very recently, we have used the expressions for the temperature dependence of the damping constant to analyze the Raman modes in NaNO 2 according to the soft mode-hard mode coupling model [23].…”

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confidence: 99%

Calculation of the Raman frequency and the damping constant of a coupled mode in the ferroelectric and paraelectric phases in KH₂PO₄

Karaçalı

Kiraci

Yurtseven

2010

Physica Status Solidi (b)

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The Raman frequency of the coupled mode v À associated with the order parameter is calculated as a function of pressure from the mean field theory in the ferroelecric phase of KDP. Using the frequencies of the coupled mode, the pressure dependence of the damping constant G À is calculated by the proton spin 1 Introduction As a ferroelectric (FE) material, KDP (KH 2 PO 4 ) was discovered [1] and its order-disorder phase transition (T C ¼ 122 K) due to the proton [2] was studied many years ago. This transition is of a second order from the paraelectric (PE) to the FE phase as the temperature decreases at the atmospheric pressure. At room temperature, this FE crystal is in the PE phase with the tetragonal structure and I42d (D

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Raman linewidths calculated as a function of temperature in NaNO₂

Cited by 9 publications

References 64 publications

Calculation of the Raman Linewidths of Lattice Modes Close to the α-β Transition in Quartz

Calculation of the Raman Linewidths of Lattice Modes Close to the α-β Transition in Quartz

Temperature Dependence of the Spontaneous Polarization Near the Ferroelectric-Paraelectric Transition in NaNO2

Calculation of the Raman frequency and the damping constant of a coupled mode in the ferroelectric and paraelectric phases in KH₂PO₄

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Raman linewidths calculated as a function of temperature in NaNO2

Cited by 9 publications

References 64 publications

Calculation of the Raman Linewidths of Lattice Modes Close to the α-β Transition in Quartz

Calculation of the Raman Linewidths of Lattice Modes Close to the α-β Transition in Quartz

Temperature Dependence of the Spontaneous Polarization Near the Ferroelectric-Paraelectric Transition in NaNO2

Calculation of the Raman frequency and the damping constant of a coupled mode in the ferroelectric and paraelectric phases in KH2PO4

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Raman linewidths calculated as a function of temperature in NaNO₂

Calculation of the Raman frequency and the damping constant of a coupled mode in the ferroelectric and paraelectric phases in KH₂PO₄