Structure and optical properties of BiFeO_3-SrBi_2Nb_2O_9 thin films using a modified sol-gel technique

Fe-doped SrBi2Nb2O9 sol was synthesized using bismuth nitrate hydrate Bi(NO3)3·5H2O,strontium nitrate Sr(NO3)2,iron nitrate Fe(NO3)3·9H2O,and niobium ethoxide Nb(OC2H5)5 as starting materials,ethylene glycol monomethyl ether(C3H8O2) as the solvent.0.1BiFeO3-0.9SrBi2Nb2O9 thin films were prepared on fused quartz substrates using sol-gel processing.The surface morphology,composition,crystal structure and optical properties of the thin films were investigated.The thin film annealing at 400℃ were found to be amorphous,and the thin films crystallize to a perovskite structure after a post-deposition annealing at 600℃ for 1h in air.The grain of thin film was evenly distributed.The thin films exhibit the designed optical transmission,while the optical transition is indirect in nature.Their optical bandgap is about 2.5eV.