Characterization of the dynamic strain response of lead magnesium niobate based ferroelectric relaxor using a fiber optic interferometer

Abstract

A high resolution optical technique is described which allows for the direct measurement of the dynamic strain response of ferroelectric relaxors. A fiber optic interferometer with strain resolution ≤10-11 (1Hz bandwidth) is utilized to probe the small strain effects in a (Pb(Mg1/3Nb2/3)O3)0.859-(PbTiO3)0.137-(SrTiO3)0.004 ferroelectric relaxor. The total macroscopic strain in the material is assumed to depend both linearly (piezoelectric term) and quadratically (electrostrictive term) on the applied electric field thereby allowing for the characterization of the material as a function of both ac and dc fields. The strain response of the material is monitored at the fundamental (f = 22kHz) and at the second harmonic. The effective piezoelectric and electrostrictive coefficients are computed as a function of temperature from the ac and dc scans and compared to the ones obtained from the low frequency sideband technique (LFST). The maximum value of the dynamic (f = 22 kHz) effective electrostrictive coefficient measured at T = 48°C was found to be 6.4 × 10-16 (m2/V2). The effective piezoelectric coefficient is found to decrease as the temperature increases while the effective electrostrictive coefficient has a maxima near 48°C. At room temperature the material is found to contain a remnant field which decreases as the temperature increases.