Piezoelectric Relaxation in Ferroelectric AgNa(NO_2)_2

概要

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The complex piezoelectric constants, d_<21>, d_<22> and d_<23>, of ferroelectric AgNa (NO_2)_2 have been measured by two quasi-static methods ; one is the optical interferometric method and the other is based on a comparison with the piezo-electric constant of quartz. The measurement covered the temperature range from 40°C to -80°C and the frequency range from 5 Hz to 50 kHz. All d_<2j>'s show dispersion of the Debye type, d_<2J>(ω)=d_<2J>(∞)+[d_<2j>(0)-d_<2j>(∞)]/(1+iωτ). The relaxation time, τ, which is of the order of 5×10^<-6> sec at room temperature coincides with the dielectric relaxation time and shows critical slowing down toward T_c (37°C). It has been found that the dipolar contribution, [d_<2J>(0)-d_<2J> (∞)], and the ionic and electronic contribution, d_<2j>(∞), are of opposite signs to one another and the static piezoelectric constant, d_<2j>(0), changes its sign at some temperature in the ferroelectric phase.
1981-12-15