| Abstract [eng] |
The modern society relies heavily on mankind’s ability to produce light to lengthen the day. Throughout the evolution of artificial lighting lots of light sources were discovered / invented, i.e. burning wood, oil, candles, using incandescent bulbs and fluorescent lamps and, finally, white LEDs. LEDs are superior to other light sources due to their high efficiency. Replacement of conventional light sources by white LEDs what would allow saving huge amounts of electricity consumed for lighting purposes. The main goal of this dissertation was development and investigation of various new materials that could be used in solid state light sources based on near-UV and blue LEDs. One silicate, one molybdate and three garnet structure compounds were selected. Several synthesis methods, i.e. solid state, sol-gel, and sol-gel combustion, were applied in preparation of selected host materials. The host materials were activated by Eu2+, Eu3+, and Ce3+ ions. The phase purity of synthesized samples was evaluated by recording powder XRD patterns. Luminescent properties of the activator ions were investigated by recording reflectance, excitation, emission spectra and decay curves at room temperature. The temperature dependent decay curves and emission spectra were recorded in the range of 77-500 K. Moreover, quantum yields, luminous efficacies and colour points were calculated from the obtained data. |
