Nd3+ ve Cr3+ katkılı metal oksit nano-tozlarında lüminesans süreçlerinin araştırılması ve beyaz ışık üretimi

The main focus of this thesis is to provide a better understanding of the effect of the crystalline size on the luminescence properties of the Nd3+ doped Y2O3 nano-powder which is one of the best host materials for rare earth ions. Hence, the present research includes the synthesis, structural and optical characterization of Y2O3:Nd3+ nano-powders. The nano-crystals of Y2O3 doped with different Nd3+ concentrations were synthesized using the thermal decomposition method which is based on the thermal decomposition of the yttrium-neodymium alginate gels. The powders were thermally treated to control the particles' sizes at temperatures ranging from 600 to 1400 oC. The synthesized powders were then structurally characterized to determine the size of the nano-particles, the morphology and the crystalline phases occurred using X-ray diffractometer and electron microscopes. The continuous emission spectra and the response to pulsed excitation measurements were conducted on the samples to determine the luminescence properties of the materials studied and to see the effect of the nano-size on the luminescence properties of the materials. The results of the optical characterization showed that the samples have enough strong emission even if they are in nano-size form and the luminescence properties of the materials are strongly related to the size of the particles. It was also shown that the Nd3+ concentration has a decisive role on the emission properties of the materials and concentration quenching effect takes place due to increasing dopant ion interactions at higher dopant concentrations. Another most important finding of this thesis which was not in its original purpose and which led us to make a patent application was the production of a bright, wideband white light emission from the studied nano-powders induced by a laser diode output. We determined most of the properties of this WL emission in detail and showed that the obtained white light emission was comparable with that of a commercial incandescent lamps and was 35 % more efficient than that of an incandescent lamp.