Nanocomposites and nanomaterials

Thin Na0.5Bi0.5TiO3 ferroelectric films on sitall substrates 
and deposition process particularities
Popov S.A.1, Kruzina T.V.1, Potapovich Yu.N.1, Rutskiy A.S.1
1 Physics and electronics dept., Oles’ Honchar Dnipropetrovsk National University, prosp. Gagarina 72, Dnipro 49010, Ukraine 
E-mail: spopov@meta.ua

In this work, the deposition of thin polycrystalline NBT films on sitall ST-32-1 substrates is investigated.
The NBT films were obtained by the high-frequency sputtering method (RF = 13.56 MHz) in Argon atmosphere (1 mTorr chamber pressure) using a three-electrode circuit. NBT ceramics of stoichiometric composition was used as the target. A thin Pt layer was deposited on the surface of the substrate to form the lower electrode.
It was established that the structure and the phase composition of the NBT films was significantly influenced by the surface morphology of the platinum layer, which significantly depends on the substrate temperature during the Pt deposition process and the thickness of the Pt layer. The substrate temperature of 300°C with a thickness of 85 nm was the most optimal for obtaining fine homogeneous polycrystalline structure of the platinum layer on sitall substrates. And XRD analysis showed that the Pt layer was free of any texture. The NBT film was deposited at the substrate covered with the Pt layer and heated to 150°C, the temperature that was optimal given the film composition contained the volatile components. The subsequent annealing was carried out in the air at 700°C for 45 minutes.
XRD analysis of the films on the sitall substrates showed the presence of a pyrovskite polycrystalline structure with reflexes 2Θ = 23°15' (100), 2Θ = 33°20' (110), 2Θ = 40°25' (111). Obtained films had the following ferroelectric parameters: ε = 700, Pr = 6 µC/cm2, Ec = 48 kV/cm. Relatively low values of the parameters can be associated with the violation of the stoichiometric composition of the film due to evaporation of volatile Na and Bi in the annealing process [1].

1.	Zhou Z.H., Xue J.M., Li W.Z., Wang J. Ferroelectric and electrical behavior of (Na0.5Bi0.5)TiO3 thin film // J Applied Physics Letters.-2004.-85, -P. 804-806.