Synthesis, Characterization and Photoluminescence Spectroscopy of Lanthanide ion doped Oxide Materials

Main thrust of this work includes exploring lanthanide luminescence for structural probe, synthesizing white light emitting materials and understanding defect induced emission in nanomaterials. Refractory materials like zirconia and thoria doped with Eu3+ have been synthesized at a low temperature using reverse micellar route and investigated the photoluminescence properties of Eu doped ThO2 and ZrO2. Luminescence properties of Eu, Dy and Sm in strontium silicate and their local site occupancy have been described. EXAFS measurements and theoretical calculations have been carried out to justify the experimental results. In SrZrO3, PL findings show that Eu3+ ions occupy both Sr2+ and Zr4+ sites and their spectral characteristics are entirely different. Optical properties of Sm, Gd and Dy doped SrZrO3 have also been discussed. Rare earth free blue emitting Sr2CeO4 has also been synthesized. An entirely new phosphate based phosphor; zinc pyrophosphate has been explored. The effect of zinc coordination on the photophysical properties of lanthanide and transition metal ion was also studied. Optical materials doped with rare earth elements are of great relevance in science and technology. Modern solid state optical technology is mainly based on lanthanide doped materials, with applications ranging from solid state lighting, field emission diodes, in-vivo fluorescence imaging, white-light-emitting phosphor for UV-LEDs, finger print detection, proton detector, lasers, dosimetry, drug delivery and optical & MRI imaging. From the scientific point of view, lanthanide doped materials attract increasing attention due to their particular physical properties. In the context of global energy shortage, energy-saving is an important issue. In the field of lighting, white light emitting diode (WLED), a new generation solid source has been highlighted due to its high luminous efficiency, low energy consumption and great potential in environmental protection. Thereafter there is a present trend to replace the traditional incandescent and fluorescent lamps. There is a tremendous growth in the development of WLED worldwide due to its various applications viz. lighting, motor vehicle and backlight for mobile panel and liquid crystal displays. Luminescent dopants are also extensively used as local probes for identifying local structures in crystalline material, understanding the effect of chemical and thermal treatment on catalysts and probing the structure of biological molecules. In view of its non-degenerate emissive state, D0, Eu (III) ion is most appropriate as a luminescent structural probe for the determination of the number of metal ion sites in a compound, their symmetry, and their respective population. Other lanthanide ions have transitions that are usually the mixtures of electric dipole transition (EDT) and magnetic dipole transition (MDT) and the effects of symmetry are less pronounced. Because of unique spectroscopic properties and luminescent dynamics of f-electron states, doping luminescent rare earth ions into nano-hosts has been demonstrated as an optimistic approach to develop highly efficient and stable nanophosphors for various applications. Compared to bulk materials, nanoparticles exhibit greater electron–hole overlap, thereby yielding greater oscillator strength and