The potential of new erbium doped materials has been assessed with the aim of enhancing and tailoring the emission properties of ER<sup>III</sup> ions (such as PL spectrum and lifetime) in pure and modified SiO<sub>2</sub> hosts through sol-gel methodologies. The main focus has been to investigate potential use of novel precursor, erbium triflate, in combination with different organophosphorus ligands, and aluminium co-dopants, for the synthesis of sol-gel thin films, bulk and power materials. This thesis describes two main approaches. In the first approach, sols were synthesised using standard sol-gel hydrolysis and condensation process. This was followed by the deposition of thin films by spin coating. After the deposition the films were thermally treated at high temperature to produce compact inorganic SiO<sub>2</sub> networks. Finally, the optical characterisation of the films has been studied. The films were optically inactive. The second approach consisted of synthesis of sol-gel bulk materials in the form of glasses and glass ceramics co-doped with Al<sup>III</sup> and P<sup>V</sup> ions, transparent glasses and glass ceramics incorporating Er<sup>III</sup> ions concentration as high as ~10 mol % were prepared containing active nanocrystallites of erbium phosphate in amorphous SiO<sub>2</sub> matrix. Optical characterisation of these glass ceramics has shown that broad and flat emission photoluminescence spectra of Er<sup>III</sup> ions with FWHM greater than 100 nm are obtained only in the materials containing ErPO<sup>4</sup> nanocrystals with average diameter of 4-5nm combined with a narrow and uniform size distribution. Visible upconversion was also detected in the Er-doped sol-gel SiO<sub>2</sub> powders under excitation at 800 and 980 nm. Excited state absorption (ESA) and energy transfer up-conversion (ETU) have been discussed as possible mechanism for visible up-conversion.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:652838 |
| Date | January 2009 |
| Creators | Ali, Muhammad Irshad |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/11098 |
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