Zhuoyue Li,Zhenlong Cheng,Maoxiu Huang,Qingkai Chen,Yuanli Liu,Zhiyi He,Jun Ou
In this paper, highly fluorescent, structurally homogeneous, and small-sized NaYF 4 upconversion nanoparticles were synthesized via the hydrothermal method, Yb/Ho/Mn co-doping altered the local symmetry of the crystals, slightly deforming their structure and enhancing the fluorescence intensity of the nanocrystals. The strong green light emission from the synthesized samples was mechanistically explained by energy transfer upconversion combined with excited state absorption process involving Yb-Mn dimers. The highest fluorescence intensity was observed with 15 mol% Mn 2+ , which increased the fluorescence intensity by a factor of approximately 10.88 compared to the undoped sample. Furthermore, this work explored the optical temperature-sensing properties of these upconversion fluorescent nanocrystals for non-contact temperature measurement, leveraging thermal and non-thermal coupling mechanisms. It provided a promising strategy for developing high-performance optical temperature sensors using other transition metal-doped lanthanide materials.
Yb,Ho:Y 2 O 3 ceramics have been fabricated by Spark Plasma Sintering method (SPS). The microstructure and transmittance of the ceramics sintered from 1623 K to 1673 K were analyzed. The highest in-line transmittance of Yb,Ho:Y 2 O 3 ceramic sintered at 1673 K reached almost 83% at 750 nm with the thickness of 1 mm. The absorption spectra , fluorescence spectra and fluorescence decay curve were recorded at room temperature. The Judd-Ofelt parameters Ω 2 , Ω 4 and Ω 6 were calculated to be 8.33 × 10 −20 cm 2 , 1.81 × 10 −20 cm 2 , and 0.82 × 10 −20 cm 2 , respectively. The intense emission cross section of Yb,Ho:Y 2 O 3 ceramic was 3.43 × 10 −20 cm 2 at 2057 nm with full width at half maximum (FWHM) of 208 nm. The results indicate that Yb,Ho:Y 2 O 3 transparent ceramic can be a promising laser gain medium for laser operation around 2 μm.
In this work, rare earth ions (REs) including Yb 3+ /Er 3+ , Yb 3+ /Ho 3+ and Yb 3+ /Tm 3+ co-doped manganese oxyfluoride glasses were fabricated using melt quenching method. By fully utilizing the upconversion luminescence (UCL) of REs and regulating energy transfer between the different energy levels of RE ions and the 4 T 1 level of Mn 2+ , the output of UCL was regulated and even pure-red light can be achieved. Moreover, owing to the selective partitioning caused by phase-separation network structure in the oxyfluoride glass, the UCL intensity of glasses annealed for 72 h is significantly enhanced 58 times compared to the rapidly quenched samples.
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