Temperature dependence of soft mode frequency, dielectric constant and loss tangent of deuterated Rochelle salt crystal

By fitting model values for physical quantities for deuterated Rochelle salt crystal in theoretical expressions for soft mode frequency, dielectric constant and loss tangent derived for Rochelle salt in our earlier studies temperature dependences of these quantities have been calculated. Theoretical results have been compared with experimental results reported in literature, which shows a good agreement. Isotope effects on both transition temperatures have been explained successfully

Temperature dependence of ferroelectric mode frequency, dielectric constant and loss tangent in CsH2PO4 and deuterated CsH2PO4 crystals

The pseudo-spin lattice coupled mode model by adding third- and fourth-order phonon anharmonic interactions and extra spin-lattice interaction term has been considered for CsH2PO4 (abbreviated CDP) and deuterated CsH2PO4 (abbreviated DCDP) crystals. Expressions for shift and width of response function, vibrational normal mode frequency, dielectric constant and loss tangent have been evaluated. Double time temperature dependent Green’s function method has been used for derivation. Fitting the values of model parameters in expressions, the temperature dependence of soft mode frequency, dielectric constant and loss tangent have been calculated. Theoretical results are in agreement with experimental results reported by Blinc et al16

Temperature Dependence of Ferroelectric Mode Frequency, Dielectric Constant and Loss Tangent in Deuterated TGSe Crystal

Abstract: By fitting model values of physical quantities for deuterated TGSe crystal in theoretically derived expressions for ferroelectric mode frequency, dielectric constant and loss tangent in our earlier paper temperature dependences of these quantities have been calculated. Present results agree with experimental data of literature value

Study of ferroelectric phase transition and dielectric properties of one dimensional hydrogen bonded crystals

114-119The third- and fourth-order phonon anharmonic interaction terms and spin-lattice interactions have been considered in the two-sublattice pseudospin-lattice coupled mode model for explaining ferroelectric transition and dielectric properties of lead hydrogen arsenate(a one-dimensional hydrogen bonded ferroelectric). Using double time thermal Green’s function technique, expressions for shift and width in frequency, soft mode frequency, dielectric constant and loss tangent have been derived for this crystal. By fitting numeric values of various physical parameters in these expressions, thermal dependences of soft mode frequency, dielectric constant and loss tangent have been calculated. Theoretically obtained thermal variations for dielectric constant has been compared with experimental data of other researchers and with experimentally correlated results for soft mode frequency, which show a good agreement

Temperature dependence of soft mode frequency and loss tangent of ammonium iron alum

The pseudospin-lattice coupled mode model has been modified by adding third-and fourth-orders phonon anharmonic interactions terms, with the help of double-time temperature dependent Green’s function method expressions.The values of ferroelectric mode frequency, dielectric constant and loss tangent have been derived. Model values of physical quantities in above expressions have been fitted. Temperature dependence of above quantities has been calculated numerically. Theoretical results have been compared with experimental results of others. A good agreement has been found

Study of dielectric properties and thermal variations of rochelle salt crystal

48-52Considering modified two sub lattice pseudo spin lattice coupled-mode model with third-and fourth-order phonon anharmonic terms and double-time Green’s function method Rochelle Salt has been investigated. Formulae for the shift, width, dielectric constant, soft mode frequency and loss tangent have been derived for Rochelle salt crystal. The numerical calculation has been done. Thermal variations of the above quantities have been obtained for Rochelle salt crystal. Our results have been compared with experimental results of other workers. Our results agree closely with those works

Temperature dependence of ferroelectric mode frequency, dielectric constant and loss tangent in PbHAsO4 crystal

The ferroelectric transition of PbHAsO4 crystal has been studied using two sublattice pseudospin-lattice coupled mode model with addition of third-order and fourth-order phonon anharmonic interactions terms. With the help of double-time thermal Green’s function method, expressions for ferroelectric mode frequency, dielectric constant and dielectric loss tangent have been derived. By fitting model values of physical quantities, temperature dependence of ferroelectric mode frequency, dielectric constant and loss tangent have been numerically calculated for PbHAsO4 crystal. Theoretical results have been compared with correlated experimental results of Arend et al.19. The results obtained in present study are in good agreement with experimental results

Study of ferroelectric and dielectric properties of potassium dihydrogen phosphate crystal

32-35A simple pseudospin lattice coupledmode model with addition of third and fourth-order phonon anharmonic interactions terms and direct spin-spin interactions terms and external electric field term has been considered for investigation of transition phenomena and dielectric properties of classic ferroelectric Potassium Dihydrogen Phosphate (KDP) crystal. A double-time thermal Green’s function method has been used for derivation of response function. From response function shift, width and soft mode frequency have been derived for KDP crystal. Response function is also related to dielectric constant which has been obtained. Unlike previous authors, some different simple approximations have been used to obtained results quite different to them. By fitting model values of different parameters in the expressions, temperature variations of normal mode frequency, dielectric constant and loss tangent have been calculated numerically for KDP crystal. Our theoretical results are compared with experimental results. It is observed that our theoretical results agree with the experimental results of Kaminow& Harding2. Therefore, it can be concluded that the simple model with still simplest approximation is quite suitable to explain transition and dielectric properties of classic KDP crystal. Present expressions can be used for similar other crystals also

By using PLCM model variation of ferroelectric properties of ammonium iron alum along with temperature

86-92Applying double-time thermal Green′s function technique24 and modifying pseudospin-lattice coupled mode (PLCM) model by adding third-and fourth-order phonon anharmonic interactions and extra spin-lattice interaction term dielectric properties of AFeSD alum have been studied. Expressions for shift, width, normal mode frequency, dielectric constant and loss tangent have been derived for AFeSD alum. Numerical calculations have been done. Theoretical results have been compared with experimental results of Pepinsky et al25. Agreement has been found

General Introduction to Ferroelectrics

In this chapter “General introduction to ferroelectrics” we contribute the basic idea of the fundamental properties of ferroelectrics. We focus on the following properties in the chapter such as basic introduction, classification, ferroelectric phase transitions, spontaneous polarization, local field, dielectric properties, polarizability, thermodynamics of ferroelectricity and applications of ferroelectrics. Ferroelectric materials are unusual dielectric which possesses reversible spontaneous electric polarization which can be reversed by application of stress or electric field which exhibit a range of properties. These properties are widely used in the today’s scientific and industrial technology. The large number of areas due to their peculiar and interesting properties such as high permittivity capacitors, ferroelectric non-volatile FeRAM memories, pyroelectric sensors, piezoelectric and transducers, electrooptic and optoelectronic devices, etc