The crystal structure and luminescence quenching of poly- and single-crystalline KYW2O8:Tb3+

Terbium-substituted KYW2O8 single crystals of high optical quality were grown by the top seeded solution growth technique. The degree of yttrium-terbium mixed occupancy was determined for two samples through structure refinements on the basis of single crystal X-ray diffractometer data. Temperature dependent magnetic susceptibility data underline the paramagnetic nature of terbium doped crystals. No magnetic ordering is evident down to 2 K. Luminescence measurements yield the typical excitation and emission spectra as expected for Tb3+ activated materials. The decay time of Tb3+ decreases linearly with the Tb3+ concentration, while the excess of thermal quenching does not change significantly. At about 405 K the decay time is reduced by roughly 50% relative to the low-temperature value, both for the powders as for the single crystals.