Electrical characterization of PMN–28%PT(001) crystals used as thin-film substrates

Abstract

Ferroelectric and piezoelectric properties of (001) $0.72{\text{PbMg}}_{1/3}{\text{Nb}}_{2/3}{\text{O}}_3–0.28{\text{PbTiO}}_3$ (PMN–28%PT) single crystals have been investigated from cryogenic temperatures to 475 K. PMN–28%PT is used as piezoelectric substrate, e.g., in multiferroic heterostructures. Electric field-induced phase transformations have been examined by electrical characterization including measurements of polarization loops, dielectric permitivitty, and the resistance change in ${\text{La}}_{0.7}{\text{Sr}}_{0.3}{\text{MnO}}_3$ films deposited on the (001) face. The relaxor ferroelectric transition behavior was studied by means of time-dependent current measurements. A phase diagram is set up. PMN–28%PT is found to be at the border of the appearance of the monoclinc phase $\left(M_C\right)$ bridging the rhombohedral-tetragonal $\left(R\text{-}T\right)$ transformation at higher ${\text{PbTiO}}_3$ contents. Measurements of the lattice expansion reveal that a high piezoelectric effect persists down to low temperatures. Therefore, PMN–28%PT single crystals are found to be appropriate substrates for application of piezoelectric strain to thin films over a broad temperature range.