Electrical Optical and Photocatalytic Property Studies in Multiferroic Gallium Ferrite Nanostructures

Abstract

The thesis describes the synthesis of nanostructures (thin films, nanocrystals, nanocubes and nanocomposites) of multiferroic GaFeO3. Structural, ferroelectric, optical, dielectric and photocatalytic properties of the samples are systematically investigated. newlinePolycrystalline thin films of gallium ferrite or GaFeO3 with (010) textured have been synthesized by sol-gel assisted spin coating deposition technique on n-Si (100) and Pt/Si newline(111) substrates. Phase and structural analysis using X-ray diffraction and Raman spectroscopy reveals the films are single phase with orthorhombic non-centrosymmetric Pc21n symmetry with the crystallite size ~37-47 nm. Temperature dependent magnetization study shows the films are near room temperature magnetic. The ferri to para magnetic transition temperature, TC ~300 K, is higher compared to bulk GaFeO3 due to the reduced crystallite size. Piezoelectric behaviour has been studied using piezo response force microscopy (PFM) which shows the ~180and#730; phase switching of the ferroelectric domains. The coercive field is very high ~ 700 kV/cm. The flat band potential is calculated using Mott-Schottky analysis. So, we can use the polycrystalline thin films of GaFeO3 in novel room temperature multiferroic devices. newlineGallium ferrite nanocrystals of truncated hexagonal bi-pyramid (THBP) shape are successfully synthesized by a controlled hydrothermal method in pure water without using any external agent. X-ray diffraction shows the nanocrystals are of P212121 symmetry. The nanocrystals are ~50 nm in size. The structural details of the nanocrystals are studied using Raman spectroscopy, high resolution transmission electron microscopy. The nanocrystals are super hydrophilic in nature and act as a visible light photocatalyst which makes the nanocrystals a self-cleaning material. newline newline