Synthesis and characterization of phosphorescent strontium aluminate compounds

Official URL: http://192.168.1.20/record=b1228190 (Table of Contents)

The emission of light after the excitation source is switched off is known as phosphorescence. Phosphorescence occurs when suitable elements with active electronic configuration are doped into certain host materials. For an efficient phosphorescence emission (long after glow time and high intensity), both the dopant ion and the host material are critical. Strontium aluminates, such as SrAl2O4, SrAl4O7, SrAl12O19, have gained attention for the last two decades due to their phosphorescence behavior upon doping with rare earth elements such as Eu, and Dy. These phosphorescent materials are superior to other materials of this kind as they have long after glow times with high quantum efficiency; they are easy to produce with alternating methods and are low cost materials. The focus of this thesis is on the different stoichiometric compounds of strontium aluminates with the dopants Eu2+, Dy3+, and boron. Eu2+ introduces phosphorescence whereas Dy3+ is used to increase the after glow time. Boron on the other hand improves the crystallinity, and also the after glow time. The general aim of this thesis is to develop materials with long after glow duration i.e more than one hour. A modified version of the Pechini process is proposed in order to accomplish the objective. The proposed procedure is one step ahead from the previous studies as it is an easy, lowtemperature and low-cost method. Moreover, by the proposed method, strontium aluminate compounds can be incorporated with up to 30% boron without disturbing the crystal lattice and hence without lowering the crystallinity. These advantages are also verified experimentally.