Effects of PMN/PT ratio on optical and electro-optic properties of PLMNT transparent ceramics

Abstract

Lanthanum modified lead magnesium niobate-lead titanate (PLMNT) transparent ceramics with composition near morphotropic phase boundary (MPB) was fabricated by a columbite precursor method with a hot-press sintering technique. The effects of PMN/PT ratio and La content on dielectric, ferroelectric and optical properties as well as the electro-optic (EO) effect of PLMNT transparent ceramics were investigated systematically. XRD patterns show pure perovskite phase of ceramics samples. Increasing PT content from 22% to 28% increases the dielectric constant and decreases the diffusivity coefficient. Meanwhile, P–E hysteresis loop gradually change from “slim” to “square”, accompanied with significant increase of Ps, Ec and Pr. Obvious decrease in optical transmittance and significant increase in EO coefficient was observed. Those observations are ascribed to the decreasing amount of polar nanodomains in PLMNT ceramics. With increasing PT content, the transition of nanodomains into macrodomains correspondingly enlarge the domain size. The largest quadratic EO coefficient achieved is 19.9×10−16 (m/V)2 for the fabricated PLMNT-3.2/72/28 transparent ceramics.