Analysis of the dielectric constant, spontaneous polarization and the coersive field close to the phase transitions in ferroelectric K2CoCl4

2016-01-01
Temperature dependence of the dielelctric constant epsilon(a) along a axis and the spontaneous polarization P-S is analyzed near the ferroelectric transition (T-C = 182 degrees C) in K2CoCl4. The power-law formula is used for the analysis of the observed data from the literature. Critical exponents we determine from our analysis indicate that K2CoCl4 exhibits a weak first order transition. Coercive field EC is also analyzed using the experimental data which decreases smoothly as the temperature increases toward the transition temperature T-C. It is concluded that the theoretical model(s) with the non-zero applied electric field, can explain the ferroelectric properties of K2CoCl4 close to the phase transitions.

Suggestions

Calculation of the spontaneous polarization for Pb1-xCaxTiO3 close to the tricritical point
Tari, O.; Yurtseven, Hasan Hamit (2016-01-01)
We calculate the spontaneous polarization as a function of temperature for a mixed crystal of Pb1-xCaxTiO3 close to the tricritical pointdx (x = 0.4). This calculation of the spontaneous polarization is performed using the effective field approximation for the dipolar (PbTiO3) and higher order ( quadrupolar and octopolar) interactions for the mixed system of Pb1-xCaxTiO3 at concentrations from x = 0 to x = 0.45.
Analysis of the Raman frequency as an order parameter close to the melting point in biphenyl
Yurtseven, Hasan Hamit (2017-05-01)
We analyze the observed Raman frequencies of the three lattice modes (modes A, B and 70cm-1) near the melting point in biphenyl by calculating the temperature dependence of the order parameter from the mean field theory. This is based on the correlation between the frequency and the order parameter close to the melting temperature (Tm=343K) in biphenyl. The Raman frequencies of the modes A and B decrease rapidly as the melting temperature is approached, whereas the Raman frequency of the 70 cm-1 is smoothly...
Calculation of the Dielectric Constant as a Function of Temperature Close to the Smectic A-Smectic B Transition in B5 Using the Mean Field Model
Yurtseven, Hasan Hamit (2012-01-01)
The temperature dependence of the static dielectric constant (epsilon) is calculated close to the smectic A-smectic B (S-A-S-B) transition (T-c = 71.3 degrees C) for the liquid crystal compound B5. By expanding the free energy in terms of the order parameter in the mean field theory, the expression for the dielectric susceptibility (dielectric constant) is derived and is fitted to the experimental data for epsilon which was obtained at the field strengths of 0 and 67 kV/cm from literature. Coefficients in t...
Analysis of the Critical Magnetic Field and the Dielectric Susceptibility for the Smectic A-Smectic C* Transition in DOBAMBC
Yurtseven, Hasan Hamit (2015-01-01)
The temperature dependences of the critical magnetic field H-c and the dielectric susceptibility x(at constant magnetic fields) are analyzed close to the smectic Asmectic C* transition in DOBAMBC using the experimental data according to a power-law formula. These analyses are performed below T-c in the smectic C* phase. Values of the critical exponent delta for the critical magnetic field are determined in a given temperature interval (Tc-T) with increasing and decreasing H-c. Also, values of the critical e...
Analysis of the Specific Heat for the Transitions of the Phases I-II-III-IV in (N(CH3)(4))(2)CUCl4 Crystal
Yurtseven, Hasan Hamit (2008-01-01)
The temperature dependence of the specific heat C-p is analyzed here using the experimental data according to a power-law formula with the critical exponent a for the transitions of commensurate (I), incommensurate (II) and the ferroelastic (III and IV) phases in (N(CH3)(4))(2)CUCl4 crystal. From our analysis, we extract the value of a approximate to 0 above and below T-c for the successive phase transitions of which is expected from the mean field theory (alpha =0 discontinuity), XY model (alpha =0 log) an...
Citation Formats
H. H. Yurtseven, “Analysis of the dielectric constant, spontaneous polarization and the coersive field close to the phase transitions in ferroelectric K2CoCl4,” FERROELECTRICS, pp. 15–21, 2016, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/38297.