Spectral properties and thermoluminescence of codoped PbWO4:(Mo,Y) and PbWO4:(F,Y) crystals

Abstract

AbstractLead tungstate, PbWO4 single crystals codoped with Mo6+/F– and Y3+ ions were grown using the modified Bridgman method. Optical transmission, X‐ray excited luminescence, photoluminescence, ultrashort pulsed X‐ray excited fluorescent lifetime and thermoluminescence have been investigated. Compared to pure PbWO4, the codoped PbWO4:(Mo,Y) and PbWO4:(F,Y) crystals exhibit improved transmittance in the short‐wavelength region. Luminescence and light‐yield measurements demonstrated that Mo6+/F– and Y3+ codoping could enhance the luminescence of PbWO4 and reduce slow decay components. Doped Mo6+ and F– ions in PbWO4 were tentatively considered to occupy W and O sites, while Y3+ ions codoped in PbWO4:Mo/F mostly occupy Pb sublattice sites. The second excitation peak at 335 nm, which is the second effective excitation for the enhanced blue‐green emission in as‐grown PbWO4:(Mo,Y) and PbWO4:(F,Y) crystals, should be related to MoO42– groups and O vacancies (VO). Thermoluminescence glow curve measurement between RT and 400 °C provides complementary information about trapping states and the effect of Y3+ ion codoping resulting in the reduction of stable and temporary hole centers. Further work is needed to explain the doping and energy‐transfer mechanism. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)