Ferroelectric Pb(Mg1/3Nb2/3)O3 thin films by PLD at varying oxygen pressures

Oxygen deposition pressure exerts a strong impact on the structure and ferroelectric properties of Pb(Mg1/3Nb2/3)O-3 (PMN) thin films derived from pulsed laser ablation (PLD), when perovskite PMN films on (La1/3Sr2/3)MnO3/LaAlO3 substrates were deposited at 520 degreesC and oxygen pressure varied from 0.1 to 0.6 mbar. Instead of showing the cubic structure of bulk ceramic PMN, the films exhibit a tetragonal structure, as confirmed by the splitting of (002) diffraction peak into (002) and (200) peaks. The intensity ratio of (002) and (200) increases with decreasing oxygen partial pressure. Both the remnant polarization and dielectric constant of the PMN thin films increase with decreasing deposition oxygen pressure. This is attributed to the enhancement of c-domains, which exhibit a larger polarization than that of a-domains. Typical depressed semicircles were observed in Cole-Cole curves, suggesting the coexistence of polarization relaxation and space charge relaxation in the oxygen deficient PMN films. (C) 2002 Elsevier Science B.V. All rights reserved.