Role of substrate on the dielectric and piezoelectric behavior of epitaxial lead magnesium niobate-lead titanate relaxor thin films

The effect of various substrates on the electrical and electromechanical properties of 100-nm-thick epitaxial [formula omitted] thin films is investigated. (001) 0.9PMN–0.1PT films are grown on [formula omitted] [formula omitted] [formula omitted] and MgO substrates with 40-nm-thick top and bottom [formula omitted] electrodes by pulsed laser deposition. X-ray diffraction results indicate that the films on LAO, LSAT, and STO are stressed biaxially in compression in the film-substrate interface whereas the films on MgO are stressed in tension. A decrease in the temperature of dielectric maximum [formula omitted] together with an increase in the dielectric constant and the longitudinal piezomodulus is observed with decreasing in-plane epitaxial stresses for LAO, LSAT, and STO substrates. The films on MgO substrates have the highest dielectric constant and piezomodulus with [formula omitted] below room temperature. The variation in [formula omitted] may be attributed to the shift in the transformation temperature from the paraelectric state to the relaxor state due to internal stresses in the film-substrate interface. Electrical and electromechanical properties should depend strongly on internal stresses in the vicinity of the phase transformation, which is reflected in our experimental observations. © 2000, American Institute of Physics. All rights reserved.