Compositional and structural study of ferroelectric multilayer (Pb,La)TiO3/(Pb,Ca)TiO3 sol–gel thin films

Multilayer ferroelectric thin films were prepared in this work by multiple deposition and crystallization onto TiO2/Pt/TiO2/Ti/(100)Si substrates, of (Pb0.76Ca0.24)TiO3 (PTC) and (Pb0.88La0.08)TiO3 (PTL) air stable solutions prepared by the diol sol-gel route. Two types of heterostructures were prepared: PTC/PTL/PTC and PTL/PTC/PTL. These films were studied by Rutherford Backscatering Spectroscopy. X-ray diffraction (XRD) analysis of the samples was also carried out, to determine the structural and textural characteristics of the films. RBS studies have shown that the compositions of the PTL and PTC layers in the multilayer heterostructures are close to the nominal ones. Moreover, no interdifussion has been found between the PTL and PTC layers. The RBS analysis has also shown that the TiO2 layer onto the substrate is fully incorporated in the perovskite structure during crystallization, and is related to the <111> orientation present in the PTC/PTL/PTC heterostructure. Ferroelectric hysteresis cycles have been obtained and remanent polarizations of Pr ∼38 and 27 μC/cm2 have been found in PTL/PTC/PTL and PTC/PTL/PTC heterostructures, respectively.