Effect of energy back transfer from Er³⁺ to Yb³⁺ ions on the upconversion luminescence of Er:NaYb(MoO₄)₂ and Yb,Er:NaBi(MoO₄)₂

Abstract

Under the excitation of a 980 nm laser, the visible upconversion (UC) luminescence of Er³⁺ ions doped Yb³⁺ ions selfactivated NaYb(MoO₄)₂ phosphor and crystal, as well as the Yb³⁺/Er³⁺ ions codoped NaBi(MoO₄)₂ crystal were investigated comprehensively. The results indicate that all three samples exhibit two significant green emission bands and a weak red emission band in the visible band corresponding to the transitions of ²H_11/2/⁴S_3/2→⁴I_15/2 and ⁴F_9/2→⁴I_15/2 of Er³⁺ ions, respectively. Through the variable power density spectra of three different samples, the relationship between the energy back transfer (EBT) process of Yb³⁺-Er³⁺ ions and the power density point and Yb³⁺ ion concentration was investigated. The EBT process was observed in both the Er³⁺ ions doped Yb³⁺ ions self-activated NaYb(MoO₄)₂ phosphor and crystal, as confirmed by the luminescence image of the sample. At high power density, the Yb³⁺ ions self-activated sample exhibited yellow luminescence, with the crystal appearing later than the phosphor. In contrast, the NaBi(MoO₄)₂ crystal displayed bright green emission within the measured power density range. In addition, by monitoring the relative intensity change of Yb³⁺ emission in 5 at% Er³⁺: NaYb(MoO₄)₂ crystal, the generation of EBT process in self-activated samples at high power density is more directly explained. These experimental results provide a reliable basis for our comprehensive understanding of the EBT mechanism, and also provide a reliable direction for the final determination of the optimal excitation power density for optical temperature measurement.

Graphical abstract

Keywords

Upconversion luminescence / Energy back transfer / Yb ³⁺/Er ³⁺ cooping / Phosphor / Crystal

References

[1] Dey,R., Rai,V.K.: Yb³⁺ sensitized Er³⁺ doped La₂O₃ phosphor in temperature sensors and display devices. Dalton Trans. 43(1), 111–118 (2014)

[2] Madirov,E., Busko,D., Howard,I.A., Richards, B.S., Turshatov,A.: Absolute quantum yield for understanding upconversion and downshift luminescence in PbF₂: Er³⁺, Yb³⁺ crystals. Phys. Chem. Chem. Phys. 25(17), 11986–11997 (2023)

[3] Kim,D.R., Park,S.W., Moon,B.K., Park, S.H., Jeong,J.H., Choi,H., Kim,J.H.: The role of Yb³⁺ concentrations on Er³⁺ doped SrLaMgTaO₆ double perovskite phosphors. RSC Adv. 7(3), 1464–1470 (2017)

[4] Guan,Z., Li,X., Shen,R., Tian, Z., Yu,H., Cao,Y., Wang,Y., Zhang,J., Xu, S., Chen,B.: Intense red up-conversion luminescence and temperature sensing property of Yb³⁺/Er³⁺ co-doped BaGd₂O₄ phosphors. Spectrochim. Acta A Mol. Biomol. Spectrosc. 284 121805 (2023)

[5] Wang,S., Cheng,X.H., Wang,J.Y., Zhong, Z.C.: Color change upconversion mechanism of Y₆O₅F₈: Er³⁺/Yb³⁺ microtubes by using time-resolve spectra. Phys. Solid Stat. 60(7), 1381–1386 (2018)

[6] Zhang,L., Meng,Q., Sun,W., Lü S.: Temperature-sensing characteristics of NaGd(MoO₄)₂:Sm3+, Tb3+ phosphors. Ceram. Int. 47(1), 670–676 (2021)

[7] He,D., Guo,C., Zhou,S., Zhang, L., Yang,Z., Duan,C., Yin,M.: Synthesis and thermometric properties of shuttle-like Er³⁺/Yb³⁺ co-doped NaLa(MoO₄)₂ microstructures. CrystEngCom. 17(40), 7745–7753 (2015)

[8] Runowski,M., Bartkowiak, A., Majewska,M., Martín,I.R., Lis, S.: Upconverting lanthanide doped fluoride NaLuF4: Yb³⁺-Er³⁺-Ho³⁺-optical sensor for multi-range fluorescence intensity ratio (FIR) thermometry in visible and NIR regions. J. Lumin. 201 104–109 (2018)

[9] Pattnaik,S., Mondal, M., Mukhopadhyay,L., Basak,S., Rai,V.K., Giri,R., Singh, V.: Frequency upconversion based thermally stable molybdate phosphors in a temperature sensing probe. New J. Chem. 46(22), 10897–10906 (2022)

[10] Xu,S., Chen,Y., Jiang,Y., Ashraf, G.A., Guo,H.: Up-conversion La₄GeO₈: Er³⁺, Yb³⁺ optical thermometer based on fluorescence intensity ratio technique. J. Lumin. 251 119193 (2022)

[11] Jiang,T., Ye,R., Jin,X., Guo, W., Liu,X., Zhao,S., Zhang,J., Xu,S.: Size influence on optical thermometry of Er³⁺/Yb³⁺ co-doped Y₂O₃ microspheres: from TCLs and Non-TCLs. J. Lumin. 254 119471 (2023)

[12] Wang,H., Yao,J., Wei,Q., Zhao, J., Zou,B., Zeng,R.: Simultaneously achieving multicolor emission of down-shifting and up-conversion in Yb³⁺, Er³⁺-codoped Cs2NaGdCl6 double perovskites. Adv. Opt. Mater. 11(20), 2300694 (2023)

[13] Ye,S., Lei,L.: Controlled synthesis of cubic NaYF₄: Yb/Er@ NaYF₄ core/shell nanocrystals for ratiometric fluorescence temperature sensing. Chem. Phys. Lett. 833 140935 (2023)

[14] Fu,B., Yan,H., Li,R., Feng, L., Yu,Y., Gong,G., Huang,H., Liao,J.: Heterovalent Zr⁴⁺/Nb⁵⁺-cosubstituted negative thermal expansion luminescent materials with anti-thermal quenching luminescence. Laser Photonics Rev. 18(12), 2400739 (2024)

[15] Liao,J., Han,Z., Lin,F., Fu, B., Gong,G., Yan,H., Huang,H., Wen,H.R., Qiu, B.: Simultaneous thermal enhancement of upconversion and downshifting luminescence by negative thermal expansion in nonhygroscopic ZrSc(WO₄)₂PO₄:Yb/Er phosphors. Inorg. Chem. 62(24), 9518–9527 (2023)

[16] Yan,H., Li,R., Feng,L., Yu, Y., Gong,G., Huang,H., Wen,H.R., Liao,J.: Simultaneous negative thermal quenching luminescence of upconversion and downshifting processes in Al₂(WO₄)₃:Yb/Er phosphors with low thermal expansion. J. Mater. Chem. C Mater. Opt. Electron. Device. 12(32), 12353–12362 (2024)

[17] Liao,J., Wang,Q., Kong,L., Ming, Z., Wang,Y., Li,Y., Che,L.: Effect of Yb³⁺ concentration on tunable upconversion luminescence and optically temperature sensing behavior in Gd₂TiO₅: Yb³⁺/Er³⁺phosphors. Opt. Mater. 75 841–849 (2018)

[18] Li,K., Zhu,D., Lian,H.: Up-conversion luminescence and optical temperature sensing properties in novel KBaY(MoO₄)₃:Yb³⁺, Er³⁺ materials for temperature sensors. J. Alloys Compd. 816 152554 (2020)

[19] Xu,D., Liu,C., Yan,J., Yang, S., Zhang,Y.: Understanding energy transfer mechanisms for tunable emission of Yb³⁺-Er³⁺ codoped GdF₃ nanoparticles: concentration-dependent luminescence by near-infrared and violet excitation. J. Phys. Chem. C. 119(12), 6852–6860 (2015)

[20] Wang,M., Ding,S., Zhang,C., Ren, H., Zou,Y., Tang,X., Zhang,Q.: Pure-green upconversion emission and high-sensitivity optical thermometry of Er³⁺-doped stoichiometric NaYb(MoO₄)₂. Ceram. Int. 49(23), 37661–37669 (2023)

[21] Singh,V., Rai,V.K., Al-Shamery,K., Haase,M., Kim,S.H.: NIR to visible frequency upconversion in Er³⁺ and Yb³⁺ co-doped BaZrO₃ phosphor. Spectrochim. Acta A Mol. Biomol. Spectrosc. 108 141–145 (2013)

[22] Walton,I.M., Cox,J.M., Benson,C.A., Patel, D., Chen,Y.S., Benedict,J.B.: The role of atropisomers on the photo-reactivity and fatigue of diarylethene-based metal–organic frameworks. New J. Chem. 40(1), 101–106 (2016)

[23] Lacomba-Perales,R., Ruiz-Fuertes, J., Errandonea,D., Martínez-García,D., Segura,A.: Optical absorption of divalent metal tungstates: correlation between the band-gap energy and the cation ionic radius. Europhys. Lett. 83(3), 37002 (2008)

[24] Du,P., Luo,L., Yu,J.S.: Energy back transfer induced color controllable upconversion emissions in La₂MoO₆: Er³⁺/Yb³⁺ nanocrystals for versatile applications. Part. Part. Syst. Charact. 35(3), 1700416 (2018)

[25] Wang,W., Li,L., Chen,H., Wei, X., Jia,J., Pan,Y., Li,Y.: Upconversion luminescence and effect of pump power on optical thermometry of Yb³⁺/Er³⁺ co-doped YOF self-crystallization glass ceramics. Opt. Mater. 135 113330 (2023)

[26] Li,A., Xu,D., Zhang,Y., Lin, H., Yang,S., Chen,Z., Shao,Y.: Upconversion luminescence and energy-transfer mechanism of NaGd(MoO4)2:Yb³⁺/Er³⁺ microcrystals. J. Am. Ceram. Soc. 99(5), 1657–1663 (2016)

[27] Liu,J., Deng,H., Huang,Z., Zhang, Y., Chen,D., Shao,Y.: Phonon-assisted energy back transfer-induced multicolor upconversion emission of Gd₂O₃: Yb³⁺/Er³⁺ nanoparticles under near-infrared excitation. Phys. Chem. Chem. Phys. 17(23), 15412–15418 (2015)

[28] Mo,Z., Su,S., Huo,Y., Wen, H., Suchocki,A., Hakeem,D.A.: Enhanced dual mode luminescence via energy transfer in Er³⁺, Yb³⁺ co-doped β-spodumene. J. Alloys Compd. 872 159551 (2021)

[29] Chen,G., Somesfalean, G., Liu,Y., Zhang,Z., Sun,Q., Wang,F.: Upconversion mechanism for two-color emission in rare-earthion-doped ZrO₂ nanocrystals. Phys. Rev. B Condens. Matter Mater. Phys. 75(19), 195204 (2007)

[30] Sukul,P.P., Kumar,K., Swart,H.: Erbium energy bridging upconversion mechanism studies on BAKL:Er³⁺/Yb³⁺ glass-ceramics and simultaneous enhancement of color purity of the green luminescence. Dalton Trans. 51(7), 2827–2839 (2022)

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