Optical transition properties, internal quantum efficiencies, and temperature sensing of Er3+ doped BaGd2O4 phosphor with low maximum phonon energy

The hosts with low maximum phonon energy (MPE) are preferred since the nonradiative consumption of the luminescence centers in them are low. Among the low MPE hosts, the oxide ones are more favored owing to their excellent stability and easy synthesis. In this work, the optical and spectroscopic properties of BaGd2O4:Er3+ phosphor were studied. The MPE of BaGd2O4 host was observed from Eu3+ phonon sideband (PSB) spectrum and Raman spectrum to be 477 cm(-1) which does not second to the fluoride hosts. The refractive index, which is indispensable for Judd-Ofelt calculation, was confirmed from the both approaches of the Eu3+-probe and the band gap energy, and the similar refractive indices were confirmed, therefore the average refractive index 2.01 was used in the Judd-Ofelt calculation. The Judd-Ofelt parameters of Er3+ in BaGd2O4 host was confirmed to be omega 2= 7.91 x 10(-21) cm(2), omega 4= 2.36 x 10(-21) cm(2), and omega 6= 9.00 x 10(-22) cm(2). Furthermore, the internal quantum efficiencies for F-4(9/2) and I-4(J) (J = 9/2, 11/2, and 13/2) levels were determined. Finally, the optical temperature sensing properties were studied in detail, and the temperature calibration curve was experimentally derived, meanwhile the maximum absolute sensitivity was confirmed to be 0.0028 K-1.

Automated summary

In this study, the optical and spectroscopic properties of BaGd2O4:Er3+ phosphor were investigated. The host material was found to have low maximum phonon energy and excellent stability. Experimental and calculated parameters were obtained for the host material, and the quantum efficiencies for different levels were determined. The application of the material in optical temperature sensing was also explored.