Piezoelectric resonance in Rochelle salt: The contribution of diagonal strains

Abstract

Within the framework of two-sublattice Mitsui model with taking into account the shear strain ε 4 and the diagonal strains ε 2 and ε 3 , a dynamic dielectric response of Rochelle salt X-cuts is considered. Experimentally observed phenomena of crystal clamping by high frequency electric field, piezoelectric resonance and microwave dispersion are described. It is shown that the lowest resonant frequency is always associated with the ε 4 shear mode

Defect-mediated relaxation and non-linear susceptibilities of Rochelle salt

“…Figure 1: Temperature dependences of the lowest resonance frequency of the Rochelle salt X-cut with l y = 1.60 cm, l z = 2.45 cm . Solid line: the present theory with the defect-mediated relaxation, A 0 = 1.1 • 10 −4 , E b = 4.5 • 10 3 V/m, τ 0 = 5.95 • 10 −16 s, W = 0.5 eV; dashed line: the earlier theory[23]. Symbols: experimental points of[9].…”

“…This field gives rise to the shear strain ε 4 at all temperatures, as well as to the diagonal strains ε 1 , ε 2 , ε 3 in the ferroelectric phase. Influence of the in-plane extensional vibrational modes associated with ε 2 and ε 3 on the dynamic permittivity of Rochelle salt X-cuts has been explored in detail in [23]. In particular, it was shown that the extensional modes are excited only in the ferroelectric phase (as follows from the system symmetry), and that the lowest piezoelectric resonance frequency is always associated with the shear mode.…”

“…The observable linear dynamic dielectric susceptibility is expressed via the derivative from the polarization averaged over the sample volume [23]. Symbols: experimental points of [9].…”

“…The choice of the values of A 0 and other model parameters is discussed in Section 5. Figure 1 shows the lowest resonant frequency ν 00 = ω 00 /2π of a rectangular Rochelle salt X-cut, calculated within the model without the defect-mediated relaxation [23] and within the present model. Both theories yield identical results for all temperatures except for the very narrow regions around the Curie temperatures.…”

“…This field gives rise to the shear strain ε 4 at all temperatures, as well as to the diagonal strains ε 1 , ε 2 , ε 3 in the ferroelectric phase. Influence of the in-plane extensional vibrational modes associated with ε 2 and ε 3 on the dynamic permittivity of Rochelle salt X-cuts has been explored in detail in [23].…”