PULSED LASER DEPOSITION OF BaCe0.85Y0.15O3 FILMS

摘要

Pulsed laser deposition has been used to grow nanostructured BaCeo.ssYo.isOa-s films.The objective is to enhance protonic conduction by reduction of membrane thickness.Sinteredsamples and laser targets were prepared by sintering BaCe0.85Y0.15O3-δ powders derived by solidstate synthesis.Films 2 to 6 μm thick were deposited by KrF excimer laser on Si and poroussubstrates.Nanocrystalline films were fabricated at deposition temperatures of 600-800 °Cat O2 pressure of 30 mTorr and laser fluence of 1 .2 J/cm 2 .Films were characterized by x-raydiffraction,scanning electron microscopy and electrical impedance spectroscopy.Dense singlephase BaCe0.85Y0.15O3-δ films with a columnar growth morphology is observed,preferred crystalgrowth was found to be dependent upon deposition temperature and substrate type.Electricalconductivity of bulk samples produced by solid state sintering and thin film samples weremeasured over a temperature range of 100 °C to 900 °C in moist argon.Electrical conduction ofthe fabricated films was 1 to 4 orders of magnitude lower than the sintered bulk samples.Withrespect to the film growth direction,activation energy for electrical conduction is 3 times higherin the perpendicular direction than the parallel direction.