Upconversion luminescence of Gd₂O₃:Er³⁺and Gd₂O₃:Er³⁺/silica nanophosphors fabricated by EDTA combustion method

Le Quoc Minh¹，Tran Kim Anh¹，Nguyen Duy Hung²，Pham Thi Minh Chau¹，Nguyen Thi Quy Hai¹，Ho Van Tuyen¹，Vu Thi Thai Ha³，Vu Duc Tu³，Wieslaw Strek⁴

1. Institute of Theoretical and Applied Research,Duy Tan University2. Advanced Institute for Science and Technology,Hanoi University of Science and Technology3. Institute of Materials Science,Vietnam Academy of Science and Technology4. Institute of Low Temperature and Structure Research,Polish Academy of Science 2 Okolna

摘 要：Gd₂O₃:Er³⁺ nanophosphors were fabricated by the combustion method in presence of Na₂ ethylene diamine tetra acetic acid（EDTA-Na₂） as fuel at not high temperature（≤350℃） within a very short time of 5 min.The added concentration of Er³⁺ions in Gd₂O₃ matrix was changed from 0.5 mol% to 5.0 mol%.The X-ray diffraction pattern of samples indicates the monoclinic structure of Gd₂O₃:Er3+.The morphology and chemical composition analysis of the Gd₂O₃:Er³⁺ samples are characterized by a field emission scanning electron microscope（FESEM） and a Fourier-transform infrared spectrometer（FTIR）.The photoluminescence（PL）,photo luminescence excitation（PLE） and upconversion（UC） at room temperature of the prepared materials with different concentrations of Er³⁺ were investigated.The PL of Gd₂O₃:Er³⁺nanomaterials are shown in visible at 545,594,623,648,688 nm under excitation at 275 nm.The emission bands from transitions of Er³⁺ from ²P_3/2 to ⁴F_9/2 are observed,UC luminescent spectra of the Gd₂O₃:Er³⁺/silica nanocomposites under 976 nm excitation show the bands at 548 and 670 nm.The influence of excitation power at 980 nm for transitions were measured and calculated.The results indicate that the upconversion process of Gd₂O₃:Er³⁺/silica is two photons absorption mechanism.The low temperature dependence of UC luminescent intensities of the main bands of Gd₂O₃:Er³⁺was investigated towards development of a nanotemperature sensor in the range of 10-300 K.

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