Fabrication And Electrochemical Properties Of (STO/YSZ/SDC)_N Superlattice Electrolyte Film

This study is focused on characterization of the low temperature properties of?STO/YSZ/SDC?_N superlattice films which were sequentially sputtered on MgO single crystal substrate by pulsed laser deposition?PLD?method.The surface morphology,sectional drawing,phase,composition and element content of four?STO/YSZ/SDC?₂ superlattice electrolyte film samples at different substrate temperatures?600,650,700,750??were observed by scanning electron microscope?SEM?,X-Ray diffraction,Energy Dispersive X-ray Detector?EDX?.The electrochemical impedance spectroscopy of sample films were measured by electrochemical work station Agilent 4291B at different measured temperatures.SEM shows that it's very important for substrate tempertature to fabricate films.The migration and adhesion of atoms on the surface would be improved with the substrate temperature increase,at the same time the quality of films was improve too.Uniform films of closely spaced,homogeneous with columanar morphology have been formed,interfaces were clear and smooth,at substrate temperature were 700?.So We choose 700? as the best substrate temperature for fabricating electrolyte films.Based on above results,four?STO/YSZ/SDC?_N film samples with different modulation periods?N=3,5,10,20?and same thickness 400nm were sputtered on MgO single crystal substrate by pulsed laser deposition?PLD?method in second experiment.The third experiment has the same conditions with experiment two except thickness ratiowhich range form 1:1:1 to 1:1:3.The result shows that uniform films of closely spaced,homogeneous with columanar morphology have been formed for all samples according to SEM and TEM.Cross-section TEM drawing shows that interfaces were clear and smooth.Superlattice structure can be reveal by XRD,more and more satellite peaks appears in the zero-order diffraction peak around with the numbers of interface increase.With the number of interfaces increase,the ionic conductivity of?STO/YSZ/SDC?_N superlattice film increase.We found that the ionic conductivity of?STO/YSZ/SDC?_N superlattice film increase with thickness ratio of SDC increase by compared second experiment with third experiment.