La-graded hetero structures of Pb1-xLaxTiO3 thin films

This work presents the preparation of La-graded heterostructure thin films and their property comparison with those of conventional thin films of similar compositions. La-graded heterostructure films were prepared on platinum substrates using sol-gel technique. These films showed relatively higher values of P-m and P-r (68 and 38 muC/cm(2), respectively) and excellent dielectric properties with lower loss and higher dielectric constant (K = 1900, tandelta = 0.035 at 100 kHz). AC electric field dependence of the permittivity at sub-switching fields in terms of Rayleigh law was investigated for both conventional 15 at.% La-doped PbTiO3 and La-graded heterostructure films. The estimated irreversible domain wall displacement contribution to the total dielectric permittivity was 17% and 9% for conventional and graded heterostructure films, respectively. (C) 2002 Elsevier Science B.V. All rights reserved.