EFFECT OF Sr-DOPING ON FERROELECTRIC AND DIELECTRIC PROPERTIES OF SOL-GEL SYNTHESIZED BaTiO3 THIN FILMS.

Multicrystalline Sr-doped BaTiO3 having the compositional formula BaTiO3+ xSr (BTS), for x = 0.0, 0.025, 0.05, 0.1, 0.2, and 0.3 films have been obtained by sol-gel method. The films have been coated on Ti-substrates by means of spin - coating process. The effect of Sr-doping on the dielectric, ferroelectric and structural properties of the BTS films was studied by various characterization procedures. The X-ray diffraction (XRD) plots of BTS films show a slight shift in diffraction peaks to the higher 2-theeta diffraction angle with the addition of Sr-content. Lattice parameters are calculated using XRD patterns and tetragonal phase structure has been confirmed. It is also observed that there is no phase change due to dopant incorporation. The XRD peaks become more sharp with increasing Sr-dopant concentration showing the improvement in crystallinity of the films. Scanning electron microscopy (SEM) of BTS films displays the crack free as well as uniform nature of the grown films. The EPMA data verified films compositions. The electrochemical measurements of BTS films display the variation of the current density (J) with the applied voltage (V). The polarization-voltage (P-V) measurements of these thin films annealed at 750 oC shows the reduction in the ferroelectric properties with addition of Sr-content. On the other hand dielectric constant -frequency (εr - f) measurements reveal that dielectric constant increases with Sr-dopant concentration. Among these BTS films, the compositions BaTiO3+0.3Sr films have the maximum value of the dielectric constant 2.95041x10-35 measured at 10MHz frequency. The ferroelectric and dielectric properties of the sol-gel synthesized BTS thin films are influenced by the Sr-dopant concentration. The prominent effect of doping on both dielectric and ferroelectric properties of a material is highly appreciated for making high frequency devices. [ABSTRACT FROM AUTHOR]