Ferroelectric silver niobate-tantalate thin films

Submicron thick ferroelectric AgTa0.38Nb0.62O3 (ATN) films have been prepared by pulsed laser deposition technique onto Pt80Ir20 polycrystalline and La0.7Sr0.3CoO3/LaAlO3 single crystal substrates. ATN/Pt80Ir20 films have been found to be (001) preferentially oriented, while the epitaxial quality of ATN/La0.7Sr0.3CoO3/LaAlO3 heterostructures has been ascertained. Comparative analysis of the temperature and frequency dependencies of the dielectric permittivity epsilon' and loss tan delta in ATN films and bulk ceramics shows that in films: the coupled structural-ferroelectric monoclinic M-1-to-monoclinic M-2 phase transition occurs at the temperature 60 degrees lower than in ceramics, thus the temperature stability of epsilon' and tan delta in films is improved and occurs in extended temperature range. Reliable tracing of the ferroelectric hysteresis polarization versus electric loops indicates the ferroelectric state in ATN films at temperatures below 125 K and yields the remnant polarization of 0.4 muC/cm2 @77 K. Weak frequency dispersion, high temperature stability of the dielectric properties, as well as low processing temperature of 550 degreesC, are the most attractive features of ATN films. (C) 2000 American Institute of Physics. [S0003-6951(00)03352-0].