JOURNAL OF APPLIED PHYSICS
·
2021
·Vol. 129
·期 5
·
IF 2.546
Jiao Yan,Guo Mengting,Wang Renle,Shao Chongyun,Hu Lili
In this study, Er 3+ /Al 3+ co-doped silica glasses with various Al/Er ratios ranging from 0 to 200 and a constant Er 2 O 3 amount were prepared using the sol-gel method combined with high-temperature vacuum sintering. The absorption, emission spectra, and fluorescence lifetime of Er 3+ ions were recorded and the absorption and emission cross sections were calculated. Using Raman, 27 Al and 29 Si magic angle spinning nuclear magnetic resonance (MAS-NMR), 27 Al triple-quantum (TQ)-MAS-NMR, and electron paramagnetic resonance (EPR) spectroscopies, the physical and optical properties were correlated with the glass structural modifications due to the Al/Er ratio change. With the increase in the Al/Er ratio, the content of Al 3+ ions around the Er 3+ ions gradually increased. Meanwhile, the AlO 5 and AlO 6 polyhedrons increased at the expense of the AlO 4 and SiO 4 tetrahedrons, which resulted in an improved symmetry and better ionic Er–O bonds. These structural changes led to the site-to-site variations in the Er 3+ local environment and the changes in the ligand field strength of the Er–O bonds. This, in turn, resulted in the inhomogeneous broadening of the absorption and emission spectra, with a blue shift of both absorption and emission peaks and a decrease in both absorption and emission at 1.53 μ m. With the increase in Al/Er ratio, the full width at half maximum (FWHM) of the emission increased from 27.2 to 54.3 nm. The FWHM × emission cross section ( σ e m i ) parameter for evaluating broadband amplification behavior was 30.1 × 10 −20 cm 2 · nm. This work reveals the close relationship between the glass structure and the spectroscopic properties of Er 3+ ions and provides an important reference for the design of broadband amplifier materials in the field of optical communication.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
CRYSTAL GROWTH & DESIGN
·
2021
·
IF 4.076
Jing Wang,Shuping Xu,Houyu Zhang,Lei Chen,Shulin Guan,Weiqing Xu
A novel strategy for constructing the organic core–shell structures/heterostructures (OCSHs) was developed by the surface doping of a charge transfer (CT) Py-TFP cocrystal (Py = pyrene; TFP = tetrafluoroterephthalonitrile) with the donor (D) or acceptor (A) replacement reaction. The lattice-selective doping of Pe (Pe = perylene) or TCNB (TCNB = 1,2,4,5-tetracyanobenzene) molecules on the Py-TFP surface resulted from both the molecular size match/mismatch and the distribution of the intermolecular hydrogen bonds. Spectroscopic analyses disclosed that the components of two types of lattice-oriented external shells, (Py-TFP)1–x(Pe-TFP)x and (Py-TFP)1–y(Py-TCNB)y, have the doping ratios of 0 < x ⩽ 2.00% and 0 < y ⩽ 4.03%, respectively. Their di-block core–shell heterostructures display the spatially segregated yellow-blue dual-color emission and the position-dependent optical waveguide with active and passive waveguide modes. Meanwhile, the Pe doped Py-TFP core–shell cocrystal presents (1,0,0) and (0,1,1) lattice-dependent emission and lightwave transmission. This study provides an effective fabrication strategy for the OCSH construction, and this core–shell cocrystallized heterojunction can be available for photonic and optoelectronic functional applications.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
ChemistrySelect
·
2024
·Vol. 9
·期 21
·e202401644
·
IF 1.9
Qi Shi,Pan Cao,Siqi Huang,Zhixin Ren,Yuguang Lv,Tai Peng
Graphical Eu/g-C 3 N 4 composites were prepared and the optimum elemental doping ratio was proved experimentally. The good photocatalytic activity of the composites was determined by the degradation rate of antibiotic drugs under visible light irradiation and explore its photocatalytic mechanism. Graphene-like materials were prepared by thermal copolymerization using melamine as a precursor, and chemical methods successfully synthesized Eu/g-C 3 N 4 composites containing different europium elements. Degradation rates of 64.3 %, 91.9 %, and 72.8 % were observed in the photocatalytic degradation of Pefloxacin, Enrofloxacin, and Ciprofloxacin under visible light (λ>550 nm). Determine the photocatalytic activity of the composite. When the doping amount was Eu/g-C 3 N 4 -2 with k=0.0135 min −1 , four times greater than that of g-C 3 N 4 , the best photocatalytic effect was obtained. Repeated studies revealed that the Eu/g-C 3 N 4 composite samples had good cycle stability, and a potential degradation process was postulated.
研究领域:
材料科学
·
环境科学
·
药学
✓ 已验证
产品关联
DOI
高影响因子
Nanomaterials
·
2023
·Vol. 13
·期 5
·917
·
IF 5.3
Donglin Li,Junfeng Lu,Xuanji Zhang,Dingfeng Jin,Hongxiao Jin
Nanoscale heterostructured zinc oxide/reduced graphene oxide (ZnO/rGO) materials with p–n heterojunctions exhibit excellent low temperature NO2gas sensing performance, but their doping ratio modulated sensing properties remain poorly understood. Herein, ZnO nanoparticles were loaded with 0.1~4% rGO by a facile hydrothermal method and evaluated as NO2gas chemiresistor. We have the following key findings. First, ZnO/rGO manifests doping ratio-dependent sensing type switching. Increasing the rGO concentration changes the type of ZnO/rGO conductivity from n-type (<0.6% rGO) to mixed n/p -type (0.6~1.4% rGO) and finally to p-type (>1.4% rGO). Second, interestingly, different sensing regions exhibit different sensing characteristics. In the n-type NO2gas sensing region, all the sensors exhibit the maximum gas response at the optimum working temperature. Among them, the sensor that shows the maximum gas response exhibits a minimum optimum working temperature. In the mixed n/p-type region, the material displays abnormal reversal from n- to p-type sensing transitions as a function of the doping ratio, NO2concentration and working temperature. In the p-type gas sensing region, the response decreases with increasing rGO ratio and working temperature. Third, we derive a conduction path model that shows how the sensing type switches in ZnO/rGO. We also find that p–n heterojunction ratio (np–n/nrGO) plays a key role in the optimal response condition. The model is supported by UV-vis experimental data. The approach presented in this work can be extended to other p–n heterostructures and the insights will benefit the design of more efficient chemiresistive gas sensors.Keywords:p–n junctions;ZnO;reduced graphene oxide;rGO;NO2sensing
研究领域:
材料科学
·
传感器技术
·
纳米科技
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SENSORS AND ACTUATORS B-CHEMICAL
·
2022
·
IF 9.221
Yiran Zhang,Chunping Wu,Bang Xiao,Lin Yang,Anqi Jiao,Ke Li,Ting Chen,Reggie Zhan,Zhen Huang,He Lin
Detection of NO 2 attracted increasing interest to check the air quality and monitor exhaust emission of combustion facilities. In this study, the flame spray pyrolysis (FSP) method was used to prepare the La-doped WO 3 nanoparticles as NO 2 sensing materials for the first time. The FSP-made La-doped WO 3 nanoparticles showed that the doped La atoms were dispersed homogeneously on WO 3 particles in the form of La 2 O 3 . It was observed that in the concentration range of 150–1200 ppb at 125 ℃ , the WO 3 sensing responses were enhanced by La doping from 2.5 at% to 10 at%, and exhibited the highest sensing response when the La doping ratio was 7.5 at%. The 7.5 at% La-doped WO 3 shows the highest response (74.2) toward 900 ppb NO 2 at 125 ℃ with response/recovery times of 23 and 35 s. Then, the high-resolution XPS spectra and sensing mechanism were combined to investigate the La-doping effects, it can be found that the enhancement of La doping might result from the enriched vacancy oxygen and more absorption sites, as well as the p-n heterojunction that drives more electrons to react with NO 2 . Moreover, the sensor using 7.5 at% La-doped WO 3 presented an excellent anti-interference performance to single NH 3 , SO 2 , CO, CO 2 , and CH 4 , but were disturbed by ppm-level NH 3 and SO 2 coexisted with NO 2 . It also exhibited good resistance to RH fluctuation and good stability.
研究领域:
材料科学
·
环境监测
·
纳米技术
·
传感器
✓ 已验证
DOI
高影响因子
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