Preparation And Characterization Of Cerium Oxide By Magnetron Sputtering

CeO₂ belongs to the cubic crystal system,the crystal structure is fluorite type,and the octahedral gap position is empty.The cerium ions in cerium oxide exist in the valence states of +3 and +4,and the transition between these two valences can be achieved in different oxygen environments?oxygen enrichment and oxygen deficient?.Because cerium oxide itself can achieve the transformation of these two valence states,cerium oxide can store and release oxygen,and its structure can still maintain fluorite type.Cerium oxide with its own unique structural properties,can be used in the permanent magnetic materials,optical glass,fast ion conductor,automotive catalyst and so on.Although many studies have been carried out on cerium oxide,there have been few reports on changes in texture and morphology of cerium oxide films during experiment.The growth of these films directly affects the structure and its final properties.In this paper,cerium oxide films were prepared under different deposition conditions by RF magnetron sputtering method.XRD and SEM were used to observe the changes of texture and morphology of cerium oxide films.The different cerium oxide films doped with nitrogen and magnesium were characterized by XRD and SEM.The cerium oxide coatings with different sputtering time was prepared under the same deposition conditions.The growth mechanism of cerium oxide coatings was studied by AFM.The main contents of this thesis are summarized as follows:?1??111?texture and?200?texture change under different gas flow rate.When the gas flow ratio is?Ar: O₂?= 30: 5 sccm,the morphological features of the coatings are the same There are some differences in the other samples.The deposition rate of the films increases first and then decreases with the increase of oxygen partial pressure.?2?Under different sputtering conditions,cerium oxide has a significant?111?preferred orientation or?200?preferred orientation.As the sputtering pressure increases,the texture of cerium oxide coatings changes?200?to?111?.The morphology of the film under the condition of 0.4Pa is very different from that of the other samples.It is made up of small particles and it is denser.The deposition rate of cerium oxide films was 2.0nm/min under the condition of 0.4Pa,and increase to 4.0nm/min under other conditions.?3?Under different deposition temperature conditions,the crystal texture of cerium oxide has no obvious rule.At 200 and 800 ? ?,cerium oxide has obvious?111?and?200?preferred orientations.With the increase of deposition temperature,the morphology of cerium oxide film is obviously different.The deposition rate of cerium oxide is 2.5nm / min at 800 and 4.0nm / min in other conditions.??4?The nitrogen-doped cerium oxide prepared at different deposition temperatures has no change in morphology and the crystal structure.By changing the power of the magnesium target,the prepared magnesium doped cerium oxide has almost no change in its morphology and is similar to that of the previously prepared cerium oxide.?5?At temperatures of 400 ?,the preferential orientation of the coatings changed from?200?to?111?with the increase of the sputtering time.From the SEM results,it can be seen that the grains grow from the aggregated small balls into loose triangles.AFM results show that the growth of cerium oxide can be divided into two stages.The growth index of the first stage is 0.49±0.08,the growth index of the second stage is 1.91±0.08.?6?The cerium oxide deposited under different time at 800 ?shows?200?texture,and its morphology are first developed from the small pellets of aggregates into individual grains that are elongated into triangular shapes,and then generate the shape of the quadrilateral particle aggregation,and finally generate individual crystal abnormal growth into tetrahedral morphology.The growth process can be divided into two stages,the growth index of the first stage is 0.57±0.04,and the the growth index of the second stage is 2.56±0.36.In this paper,the influence of deposition conditions on the structure and morphology of cerium oxide and the influence of anion doping and cation doping on the structure and morphology of cerium oxide were discussed.The effects of cationic doping on the structure and morphology of cerium oxide were discussed.The structure of the cerium oxide is controlled by the magnetron sputtering method.