Thermoluminescence properties of isostructural K2YF5 and K2GdF5 crystals doped with Tb3+ in response to α, β and X-ray irradiation

The thermoluminescence (TL) properties of isostructural fluoride K2YF5 and K2GdF5 crystals doped with Tb3+ of different concentrations have been studied in the temperature range from 30 to 500 °C after α, β and X-ray irradiation. Strongly different structures of TL glow curves following α or β irradiation have been found for Tb3+ doped K2YF5 for all studied concentrations of Tb3+ whereas for K2GdF5 crystals the different TL curves after α or β irradiation are detected only for heavily doped samples. On the other hand, all the studied materials show similar TL glow curves after β or X-ray irradiation. It has been discovered that K2YF5 doped with 1 at.% Tb3+ has TL radiation sensitivity to β irradiation of the same order as that of the well known TLD-100 (LiF:Mg,Ti) phosphor and much higher sensitivity to α irradiation. The TL mechanism in K2YF5 and K2GdF5 doped with Tb3+ is discussed by taking into account the TL emission spectra from irradiated samples, which are identical to the emission spectra of the Tb3+ ions in these hosts under photo-excitation, and the kinetics parameters obtained with the method of various heating rates.