Papers by Author: Julian Plewa

Abstract: UV emitting luminescent materials are of strong interest for UV emitting fluorescent lamps driven by a Hg low-pressure or a by Xe excimer discharge. Pr3+ doped host lattices exhibit efficient UV emission upon deep UV excitation, if the site of the host lattice, where Pr3+ is located, is suitable for this purpose. This work deals with Pr3+ activated VUV ceramic luminophores, i.e. materials, which show efficient luminescence upon 160 nm excitation. As host lattices for the potentially UV emitting Pr3+ ion aluminates and silicates have been studied. All samples were prepared by conventional mix and fire synthesis techniques with metal oxides as starting materials. Firstly, powder samples were annealed between 1000 and 1700 °C and secondly, ceramic samples were repeatedly thermally treated at similar temperatures after pressing. It is demonstrated that translucent ceramics show mainly UV luminescence upon deep UV excitation, while excitation by a blue 450 nm LED results in green to red luminescence with a similar decay time as observed for single crystals.

Abstract: In this review a small overview is given about methods of powder preparation and thick films tested in the field of High-Temperature-SuperConductors (HTSC). The first and very important step on the way to applications consists generally in the preparation of an adequate powder, alternatively prepared by the common ceramic way or tailor made by wet chemistry. Following, the preparation of thick films are discussed, mostly made by low cost processes in contrast to the expensive manufacturing of thick films.