Temperature Dependence of Soft Mode Frequency and Dielectric Constant in Ferroelectric PbHPO[sub 4] Crystal

2011 ◽  
Author(s):  
Trilok Chandra Upadhayay ◽  
Mayank Joshi ◽  
P. K. Bajpai ◽  
K. S. Ojha ◽  
K. N. Singh
Keyword(s):  
Dielectric Constant ◽  
Temperature Dependence ◽  
Soft Mode ◽  
Mode Frequency

scholarly journals Calculation of the Spontaneous Polarization and the Dielectric Constant as a Function of Temperature for

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Hamit Yurtseven ◽  
Sema Şen
Keyword(s):  
Dielectric Constant ◽  
Transition Temperature ◽  
Temperature Dependence ◽  
Spontaneous Polarization ◽  
Atmospheric Pressure ◽  
Ferroelectric Phase ◽  
Paraelectric Phase ◽  
Soft Mode ◽  
Increasing Temperature ◽  
Mode Response

The temperature dependence of the spontaneous polarizationPis calculated in the ferroelectric phase of KH2PO4(KDP) at atmospheric pressure (TC= 122 K). Also, the dielectric constantεis calculated at various temperatures in the paraelectric phase of KDP at atmospheric pressure. For this calculation ofPandε, by fitting the observed Raman frequencies of the soft mode, the microscopic parameters of the pure tunnelling model are obtained. In this model, the proton-lattice interaction is not considered and the collective proton mode is identified with the soft-mode response of the system. Our calculations show that the spontaneous polarization decreases continuously in the ferroelectric phase as approaching the transition temperatureTC. Also, the dielectric constant decreases with increasing temperature and it diverges in the vicinity of the transition temperature (TC= 122 K) for KDP according to the Curie-Weiss law.

scholarly journals Theoretical Study of Dielectric Properties in Triglycine Sulphate Crystal

2021 ◽  
Vol 16 (2) ◽  
Author(s):  
Naveen Kohli ◽  
Trilok Chandra Upadhyay
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Soft Mode ◽  
Mode Frequency ◽  
Experimental Results ◽  
Tangent Loss ◽  
Spin Lattice ◽  
Coupled Mode ◽  
Interaction Terms ◽  
Crystal Model

Present paper investigate theoretically dielectric properties such as dielectric constant, soft mode frequency and tangent loss by considering two sub lattice pseudospin, spin-lattice coupled mode model (PLCM) and adding third and fourth-order anharmonic (phonon) and spin-lattice interaction terms and using thermal Green’s function (double time) method expression for dielectric constant, soft mode frequency, and tangent loss is derived for TGS crystal. Model value have been fitted in expression and their temperature dependence have been calculated for TGS crystal. Theoretical results have been correlated with experimental results of (Aravzhi et al 1997), which is approximate close to experimental results.

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

1978 ◽  
Vol 21 (1) ◽  
pp. 399-401 ◽  
Author(s):  
Ju. M. Poplavko ◽  
A. S. Knjazev ◽  
V. G. Tsykalov ◽  
L. P. Pereverzeva
Keyword(s):  
Temperature Dependence ◽  
Soft Mode ◽  
Mode Frequency
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