c-Axis oriented sol-gel (Pb,Ca)TiO3 ferroelectric thin films on Pt MgO

Ca-modified lead titanate thin films were prepared on (111)Pt/(100)MgO subs trates by spin-on sol-gel process. Two layers of 0.3 mol/l solution were de posited on the substrate and each of them subjected to drying and rapid the rmal processing (RTP) for crystallization, which reduces tensile strains. S ingle perovskite films with a preferred orientation in the direction perpen dicular to the plane of the substrate were obtained as measured by X-ray di ffraction analysis. Pyroelectricity of these films was measured before and after a polarization process being the pyroelectric coefficient close to ap proximate to 2.5 x 10(-8) C cm(-2) K-1. Ferroelectric properties were also measured, obtaining values of P-R of approximate to 25 mu C cm(-2) and E-c of approximate to 110 kV.cm(-1). Compressive strains resulting from the dif ferences between thermal expansion coefficients of the substrate and the fi lm cause the (001) orientation of the (Pb,Ca)TiO3 perovskite layer, that is very convenient for pyroelectric devices. (C) 1999 Elsevier Science S.A. A ll rights reserved.