Luminescence properties of PbWO4:Eu3+ nanocrystals synthesized by a hydrothermal method

• PbWO4:Eu3+ nanocrystals with different Eu3+ dosage concentrations were synthesized.
• The sizes of the nanocrystals increase with increasing hydrothermal temperature.
• The emission spectra show 5D0→7FJ transitions of Eu3+.
• The PWO:0.05Eu3+ nanocrystals have the highest intensities of emission bands.

PbWO4:Eu3+ nanocrystals were synthesized by the hydrothermal method at different temperatures. Their luminescence properties were studied systemically. The results indicate that the particle sizes of the nanocrystals increase with increasing hydrothermal temperature. Estimated according to Scherrer's equation, the crystallite sizes are in the range of 10–15 nm, 20–30 nm, and 35–40 nm at the hydrothermal temperatures of 120 °C, 150 °C, and 180 °C, respectively. Because of the slight aggregations of powders, nanocrystal sizes observed by TEM are larger than the crystallite sizes estimated by XRD patterns. The excitation spectrum shows four excitation bands. The excitation band with the maximum at 264 nm can be attributed to the charge-transfer band of W6+–O2− within the WO42− group and O–Eu CT band. The bands at 372 nm, 458 nm, and 536 nm can be assigned to the electronic transitions of Eu3+ ions. In the emission spectrum, the 5D0→7FJ transitions (J=1, 2, 3 and 4) can be observed clearly. But the band emissions caused by tungstate groups are not observed. The concentration of europium has an influence on the luminescence of samples.