PHASE COMPOSITION OF SAMARIUM NIOBATE AND TANTALATE THIN FILMS PREPARED BY SOL-GEL METHOD

摘要

Samarium niobate SmNbO4 (SNO) and tantalate SmTaO4 (STO) thin films(~100 nm) were prepared by sol-gel/spin-coating process on aluminasubstrates with PZT interlayer and annealing at 1000°C. The precursorsof films were synthesized using Nb or Ta tartrate complexes. Theimprovement of the crystallinity of monoclinic M?-SmTaO4 phase viaheating was observed through the coexistence of small amounts oftetragonal T- SmTa7O19 phase in STO precursor at 1000°C. The XRDresults of SNO and STO films confirmed monoclinic M-SmNbO4 and M?-SmTaO4 phases, respectively, with traces of orthorhombic O-SmNbO4 (inSNO). In STO film, the single monoclinic M?-SmTaO4 phase wasrevealed. The surface morphology and topography of thin films wereinvestigated by SEM and AFM analysis. STO film was smoother withroughness 3.2 nm in comparison with SNO (6.3 nm). In themicrostructure of SNO film, small spherical (~50 nm) and larger cuboidalparticles (~100 nm) of the SmNbO4 phase were observed. In STO,compact clusters composed of fine spherical SmTaO4 particles (~20-50nm) were found. Effect of samarium can contribute to the formationdifferent polymorphs of these films for the application to environmentalelectrolytic thin film devices.