Preparation, Characterization And Properties Of Ceria Powders And Films

Cerium dioxide or ceria, CeO2, has been widely used in industry as catalyst forautomotive exhaust controls, chemical mechanical polishing slurries, and hightemperature fuel cells because of its unique metal oxide properties. This well-knownrare metal oxide has high thermal stability, electrical conductivity and chemicaldiffusivity. In our work, we synthesis CeO2powder and film, and study the property.The results are as follows:1．CeO2-ZrO2(CeZr) and sulfated CeO2-ZrO2(S-CeZr) catalysts were preparedfor the selective catalytic reduction (SCR) of NO with NH3. CeZr exhibits higheractivity at low temperatures (<200°C) and lower activity at high temperature (>200°C). The sulfation of CeZr was studied in terms of surface acidity, redox propertyand NO adsorption/desorption by temperature-programmed experiments and in situ IRspectroscopy. S-CeZr displays high acidic concentration and strengthened surfaceacidities, but poor reducibility compared to CeZr. The high acidity of S-CeZr isattributed to Br nsted acid sites mainly from the contribution of surface sulfates.Because of the coverage of sulfate species on the surface of CeZr, S-CeZr shows lessNO adsorption and weak oxidation ability. The adsorbed NH3on Br nsted acid sitesrestricts the reaction with NO at low temperatures, but it is facile to fulfill the SCR cycle at relatively low temperatures such as150°C, and parts of weakly bondednitrite are active for S-CeZr at relatively high temperatures such as300°C. Thecatalytic mechanisms for CeZr and S-CeZr catalysts at150and300°C respectivelywere studied.2．A facile synthesis route to controllably tune CeO2films facets by pulsed laserdeposition (PLD) on the SrTiO3(STO)(100) single-crystal substrates was reported.By increasing the number of pulse shots, three different surface planes appeared in theCeO2films consecutively according to XRD patterns: single (100), coexistence of(100) and (110), and coexistence of (100),(110) and (111) facets, respectively. SEMimages of the CeO2films indicate that each plane displays dis-tinctive morphology:linen-like nanorods, triangle-like nanosheets and star-like nanosheets, respectively.Further, the positions of the interfaces between each structure could be confirmed byTEM images. XPS results were also provided in our work.3．Epitaxial growth of SmFeO3/SrRuO3was achieved on SrTiO3substrates by thepulsed laser deposition (PLD) method at973K under oxygen partial pressure of12.5Pa. The remanent polarization and coercive electric field of the thin film with a higherdegree of orientEtion Elong (110) were1.97μC/cm2and0.89×104V/cm at roomtemperature, respectively. From the XPS result of our sample we can see that there isalmost no Fe2+in the SFO film, which resolves the high leakage of ReFeO3-typeoxides to ensure the credibility of the polarization. This work will provide somesupports for the SmFeO3/SrRuO3/CeO2junction to increase the ferroelectric propertyof SmFeO3.