Photoluminescence properties of SrF2:3Tb@BaF2 nanoparticles and improved hyperthermia temperature achieved by core-shell nanohybrid SrF2:3Tb@BaF2/Fe3O4 materials

Abstract

SrF2:3Tb and SrF2:3Tb@BaF2 core-shell were synthesized by using ethylene glycol as solvent medium and capping agent. Both phases of SrF2 and BaF2 were observed from the XRD patterns which indicate the presence of these phases in their pure states. Since small size Tb3+ is incorporated into larger size Sr2+ lattice, there is peak shifts in the larger 2θ in SrF2:3Tb. Intensity of the XRD peaks of SrF2 was decreased when SrF2:3Tb formed core-shell with BaF2 due to the decrease of penetration depth of x-ray. There is twofold increase in the luminescence properties of Tb3+ ion in SrF2:3Tb when it formed core-shell with BaF2. Increases in luminescence intensity were also further supported by increase in weighted average lifetime values. Weighted average life time values attained for SrF2:3Tb, SrF2:3Tb@BaF2 (1:0.5), SrF2:3Tb@BaF2 (1:1), and SrF2:3Tb@BaF2 (1:2) were 6.75, 6.94, 7.42, and 7.75 ms, respectively. Further, these luminescent materials were combined with magnetic nanoparticles to form luminescent-magnetic materials which are very useful in hyperthermia applications. Hyperthermia temperature (HT) attained by 6 mg of Fe3O4, SrF2:3Tb/Fe3O4 and SrF2:3Tb@BaF2 (1:1)/Fe3O4 nanohybrid with time at fixed currents 400 A are 70, 54, and 65 °C. Thus, hyperthermia temperatures could be tuned by core-shell formation. This improvement in HT after core-shell formation can be exploited in cancer therapy. Moreover, this nanohybrid (luminescence-magnetic) material can also be detected through luminescence techniques since it contained luminescent parts also.