Dielectric enhancement in pulsed-laser-deposited (Pb,Sr)TiO3/(Pb,La)TiO3 multilayered films

Multilayered (Pb_0.5Sr_0.5)TiO₃(PST)/Pb_0.8La_0.2TiO₃(PLT)/PST and PLT/PST/PLT films were prepared on platinum coated silicon substrates by pulsed laser deposition. Significant enhancement of the dielectric constant over the whole temperature region from 30 °C up to 220 °C has been observed for both multilayers with respect to the identically prepared single-component PST and PLT films. However, larger frequency dispersion of dielectric properties has also been obtained in the multilayers. This effect is attributed to the compositional fluctuation revealed by the atomic interdiffusion in the interface regions of the multilayers. Thermally and electric-field driven space charges at relative low temperature and low electric field were found in the PLT/PST/PLT and PLT films, attributed to the substitution of La³⁺ non-isovalent for Pb²⁺ in these films. PACS 81.15.Fg; 42.70.Mp; 79.60.Jv