Search

In the presented work, the tellurite glasses TeO2-WO3-ZnO doped with Tm3+ and Ho3+ ions were prepared by the same glass forming method. X-ray diffraction (XRD) and differential thermal analysis (DTA) techniques were used to study the effects of the forming technology on the thermal and structural properties of the fabricated glasses. After controlled crystallization of investigated glasses, the emission in the VIS- and NIR range was determined. The effect of silver doping on emission intensity was investigated. The value of the activation energy of the glass crystallization process was determined, while the Ea value for pure TeO2 glass was much lower than for tellurite glasses TeO2-WO3-ZnO. [ABSTRACT FROM AUTHOR]

The reaction of several rare earth ( RE ) metals ( RE = Y, La, Ce, Pr, Eu, Gd, Tb and Lu) with gaseous hydrogen and the subsequent reaction of the resulting hydrides with nitrogen gas have been investigated by means of a combinatory approach of thermogravimetric and differential thermal analysis. Focus was laid on the fabrication of bulk material, in quantities suitable as precursor materials in further reactions, such as the synthesis of state-of-the-art phosphors for light-emitting diodes. The resulting crystalline materials were characterized by powder X-ray diffractometry and the level of purity was determined by elemental analysis of the nitrogen and oxygen content via thermal decomposition. Furthermore, detailed description of the reactivity and respective stability of the individual species in different atmospheres, i.e. argon, nitrogen and mixtures of argon with hydrogen or oxygen are presented. Finally, optimal synthesis conditions for the formation of metal hydrides as well as the nitrides are derived. Thereby, particular emphasis was placed on the minimization of oxygen contaminations during the reaction on the one hand and on the formation of homogeneous, highly crystalline materials on the other hand. [ABSTRACT FROM AUTHOR]