Tellurite glasses with the composition 67TeO 2 -3Al 2 O 3 -xZnO-(30-x)Na 2 O (x = 0–20 mol%) were synthesized via melt-quenching. Raman analysis revealed Al/Zn synergistically strengthened the network via Al-O-Te/Zn-O-Te bonds below 15 mol% ZnO, whereas excess ZnO triggered Zn 2+ /Al 3+ site competition, reducing crystallization resistance. The glass with 15 mol% ZnO (TANZ) shows optimal thermal stability ( T g = 311 °C, ΔT = 139 °C) and serves as the host for obtaining mid-infrared emission. The Ho 3+ /Yb 3+ co-doped TANZ glass shows high absorption and emission cross-sections of 7.36 × 10 –21 cm 2 and 5.86 × 10 –21 cm 2 , respectively, along with a long lifetime of 1.33 ms at 2 μm. These results highlight the potential of TANZ glasses as robust gain materials for mid-infrared fiber lasers.
Ho 3+ /Yb 3+ co-doped PbTiO 3 nanocrystals with different content of dopant were successfully prepared via a facile hydrothermal method. The purity, morphology, element distribution, chemical state and up-conversion (UC) photoluminescence (PL) of PbTiO 3 nanocrystals affected by Ho 3+ dopant are investigated systematically. X-ray diffraction (XRD) results illustrate that PbTiO 3 samples with the doping Ho 3+ concentration ranging from 0 to 5 mol-% are perovskite structure. The doping Ho 3+ ions have no change on the crystal structure of perovskite PbTiO 3 . Owing to the non-equivalent substitution of Ho 3+ to Ti 4+ in PbTiO 3 , the particle size of Ho 3+ /Yb 3+ co-doped PbTiO 3 samples is decreased as well as the particle agglomeration is detected. Moreover, Ho and Yb ions have uniform distributions in the PbTiO 3 nanoparticles as the presence of Ho 3+ and Yb 3+ cations. The up-conversion spectra demonstrate that Ho/Yb co-doped PbTiO 3 samples have up-conversion emissions centered at 550 nm, 660 nm and 755 nm, corresponding to the transitions of 5 F 4 ( 5 S 2 )→ 5 I 8 , 5 F 5 → 5 I 8 and 5 S 2 ( 5 F 4 )→ 5 I 7 of Ho 3+ ions. Additionally, the effect of temperature on the UC PL property of Ho 3+ /Yb 3+ co-doped PbTiO 3 system is further investigated. The sensitivity and the trend of Ho 3+ /Yb 3+ co-doped PbTiO 3 samples in temperature from 298 k to 493K are calculated on the basis of fluorescence intensity ratio (FIR) method. Ho 3+ /Yb 3+ co-doped PbTiO 3 nanocrystals are verified the high potential in the optical temperature sensing.
Yuhong Zhang,Nan Zhang,Pengcheng Wang,Xingke Zheng,Yibin Guo,Hang Liu
In this work, tungstate BaWO 4 phosphors doped Ho 3+ -Yb 3+ -Gd 3+ ions are successfully synthesized through solid-state reaction method. Under the excitation of a 980 nm laser, the up-conversion (UC) luminescence properties are investigated simultaneously. The blue (465 nm, 489 nm), green (541 nm) and red (665 nm) emission intensities of BaWO 4 : Ho 3+ /Yb 3+ /Gd 3+ samples are dramatically enhanced by 20.59, 9.83, 7.37, and 27.59 times more than those without Gd 3+ ions. The possible reason is discussed, which attributes to the energy transfer efficiency enhancement from Yb 3+ to Ho 3+ due to the lattice expansion induced by Gd 3+ ions. The temperature-sensing properties of BaWO 4 : Ho 3+ /Yb 3+ /Gd 3+ samples are also discussed based on the fluorescence intensity ratio (FIR) technology. The sensitivity of temperature measurement for BaWO 4 : Ho 3+ /Yb 3+ /Gd 3+ sample is higher than that of BaWO 4 : Ho 3+ /Yb 3+ . It proves that the codoped Gd 3+ ions can also increase the temperature sensitivity because the higher UC emission efficiency will lead to a high signal-to-noise ratio. The result provides an effective way to design UC luminescence materials with high temperature sensing properties.
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