Investigation on ferroelectric, dielectric and pressure sensing properties of samarium substituted lead magnesium niobate-lead titanate oxide

Abstract

In the last several decades, researchers have been developing hydraulic pressure sensors suitable in harsh oil mediums with high figures of merit. A well-known columbite method is used to prepare a series of phase pure electroceramics Pb(1-1.5y)Smy[(Mg1/3Nb2/3)1-xTix]O3 (Sm(y)-PMN(x)PT) with x = 0.20, 0.30; and y = 0.010, 0.025 for possible applications as hydraulic pressure sensors. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were carried out to study the crystal structure, microstructure, and morphology of the sintered ceramics. The frequency and temperature-dependent dielectric and ac conductivity analyses were performed over a temperature range of 300–480 K to understand the phase stability and phase transition temperatures. Room temperature (297 K) polarization-electric field and PUND analysis confirmed the large polarization (∼30–40 μC/cm2) in the investigated compositions. The hydrostatic pressure-dependent relative capacitance change was examined using a lab-made setup for different compositions for the pressure varying from 0 to 50 MPa. The percentage sensitivity varies with samarium and titanium compositions that range from 0.078 MPa−1 to 0.197 MPa−1. The highest relative change in capacitance was obtained for Pb0.963Sm0.025[(Mg1/3Nb2/3)0.80Ti0.20]O3 (Sm0.025-PMN0.20PT) ceramic with percentage sensitivity 0.197 MPa−1, nearly double to our earlier report on Pb[(Mg1/3Nb2/3)0.7Ti0.3]O3 composition. The improvement in sensitivity may be due to inherent properties, such as slim hysteresis, low tangent loss (∼0.002–0.1), large change in phase transition temperature (∼25 K) due to dielectric dispersion and relaxor-like nature compared to other investigated systems.