Structural characterisation of sol-gel SrBi2Nb2O9 thin film deposited on (001) SrTiO3 single crystal

SrBi2Nb2O9 (SBN) thin films with a thickness close to 30 nm were deposited on single crystalline (001) SrTiO3 (ST) substrate by sol-gel spin-coating. After deposition, the films annealed for 30 min at several temperatures (500, 550, 600, 650 and 700 C) were studied by XRD using a home-made diffractometer operating in asymmetric reflection geometry. Crystallisation of the precursor as pure SrBi2Nb2O9 occurs between 500 and 550 C. The normal orientation of the film occurs at 550 C, i.e. at the very beginning of the crystallisation process. Rocking curves of (0010) lines show that their full widths at half maximum (FWHM) decrease from 2.5 degrees (550 C) to 1.8 degrees (700 C), indicating that the small remaining disorientation decreases with increasing annealing temperature. A full phi-scan study of selected reflections showed that the film is heteroepitaxied on the substrate: (001) of SBN is parallel to (001) of ST and 100 axis of SBN is parallel to 110 axis of ST. 6 refs.