Spectroscopic properties of rare-earth (Eu3+, Sm3+) doped BaWO4 powders

- Eu3+ or/and Sm3+:BaWO4 were prepared by the solid state reaction method.
- Spectroscopic properties of BaWO4:Eu3+ were improved by adding Sm3+.
- The energy transfer process between Eu and Sm was discussed.
- The prepared sample is promising material for use in optical devices.

BaWO4 powders doped with rare-earth ions (RE=Eu, Sm) have been prepared by the solid state reaction method at 1100 °C. The structural and optical properties have been investigated by XRD and photoluminescence (PL) measurements, respectively. The results revealed that BaWO4 powders crystallize in the tetragonal structure and exhibit a good crystallinity. Based on emission spectra, the Judd-Ofelt parameters Ω2, Ω4 of (Eu, Sm) doped BaWO4 have been calculated. The Ω2 and Ω4 parameters have been used to calculate the total transition probabilities (AT), the stimulated emission cross-sections (σe), the fluorescence branching ratio (βR) and radiative lifetimes (τR) of the 5D0 level. The measured lifetimes (τmes) were compared to the calculated (τR) using the J-O method. The energy transfer has been investigated from the excitation spectra. The results show a broadening of the excitation bands at 396 and 465 nm of BaWO4 codoped Sm3+ and Eu3+ compared to BaWO4 doped Eu3+. The photoluminescence (PL) intensity, the luminescence decay and the quantum efficiency (η) of 5D0→7F2 transition increase after adding Sm3+. It is found that Sm3+ ion acts as sensitizer for Eu3+ ion and contributes largely to the improvement of the spectroscopic properties of BaWO4:Eu3+. We show that excitation transfer can occur from Sm3+ to Eu3+. Compared to reported materials, the radiative properties obtained for 5D0→7F2 transition (616 nm) indicate that the present sample is promising host material for Eu3+ doped fiber amplifiers.