BiLaWO6: Er3+/Tm3+/Yb3+ phosphor: Study of multiple fluorescence intensity ratiometric thermometry at cryogenic temperatures


Highly thermally stable Er3+/Tm3+/Yb3+ tri-doped bismuth lanthanum tungstate phosphors were prepared by high temperature solid-state reaction method. The structural and morphological properties of the prepared phosphors were analysed by X-ray diffraction (XRD), Raman spectroscopy and Scanning electron microscopy (SEM) coupled with energy dispersion spectrum (EDS). Visible upconversion (UC) luminescence was measured by exciting the phosphors with 980 nm laser radiation. The dependence of the UC intensity of each emission band of Er3+ and Tm3(+) ions as a function of temperature in the range from 30 to 300 K was monitored. Fluorescence intensity ratios (FIR) of thermally coupled levels (TCL) and non-thermally coupled levels (NTCL) were analysed and verified with appropriate theoretical validation. The absolute (SA) and relative sensitivities (S-R) were estimated and compared with the reported systems. In the present case of BiLaWO6: Er3+/Tm3+/Yb3+, SR (0.43 % K-1) related to TCL of Er3+ UC is found to have maximum sensitivity compared to any of the NTCL combinations at 300 K. From this study we inferred that the SR values estimated from NTCL are smaller than that of TCL involved in BLW: Er3+/Tm3+/Yb3+ phosphor. The temperature dependent CIE color coordinates were also evaluated in the cryogenic temperature region.



subject category

Materials Science


Pavani, K; Neves, AJ; Pinto, RJB; Freire, CSR; Soares, MJ; Graca, MPF; Kumar, KU; Jakka, SK

our authors


This work is funded by national funds (OE), through FCT, Portugal, I. P., in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19 and also within the scope of the project i3N, UIDB/50025/2020 & UIDP/50025/2020, financed by national funds through the FCT/MEC.

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