Paramagnetic resonance study of rare earth doped K2YF5 thermoluminescent phosphors

In the design of highly sensitive radiation detectors and solid state dosimeters for industrial, scientific and medical applications, there is a continuous interest in the development of new storage phosphors which exhibit thermoluminescence (TL) or optically stimulated luminescence (OSL). In decades of research, a large number of rare earth (RE3+) activated fluoride crystals have been found with such properties. Among those, the double alkali yttrium fluorides have recently emerged as a particularly interesting class of materials. Pr3+, Ce3+, Dy3+, Tb3+ and Tm3+-activated crystals have all been shown to possess favourable properties for use as storage phosphors for TL dosimetry. In this thesis we report the results of our EPR study of defects in Ce3+-, Tb3+-, Dy3+-doped as well as in undoped K2YF5 induced by X-rays. The investigated crystals show moderate dopant concentrations of 0.1 and 0.2 mol.%. As we focus on the relation with TL processes, experiments in which the intensity of the various EPR signals is monitored after irradiation and subsequent anneal to various temperatures above the irradiation temperature, take a central role.

Jaar van publicatie:2010

Toegankelijkheid:Closed