Co-reporter:Hongxia Guan, Chengyi Xu, Ye Sheng, Yanhua Song, Keyan Zheng, Zhan Shi, and Haifeng Zou
The Journal of Physical Chemistry C March 30, 2017 Volume 121(Issue 12) pp:6884-6884
Publication Date(Web):March 16, 2017
DOI:10.1021/acs.jpcc.7b00048
In this paper, the synthesis of rare earth fluoride GdF3 multiform morphologies via a glutamic acid hydrothermal method has been fulfilled. The size and shape of the products could be tuned just by adjusting the pH values of the initial reaction solutions. The morphologies for the products include spindle-like, peanut-like, submicrometer flowers, and nanoflowers. Additionally, the possible formation mechanism of multiform morphologies was proposed. Furthermore, we systematically investigate the luminescence properties of different lanthanide ions (Dy3+, Tb3+, and Sm3+) in GdF3 host. In the GdF3:Tb3+,Sm3+system, the energy transfer process fromTb3+ to Sm3+ was demonstrated to be resonant type via a dipole–dipole mechanism. Most interestingly, white light and multicolor light have been obtained in Tb3+ and Sm3+ coactivated or Dy3+,Tb3+,Sm3+ tridoped GdF3 phosphors. The results show that the obtained nanophosphors have a promising application in display and lighting fields.
Co-reporter:Yanhua Song, Yi Li, Tianqi Zhao, Yuexin Wang, Tingting Cui, Ye Sheng, Keyan Zheng, Xiuqing Zhou, Hongpeng You, Haifeng Zou
Journal of Colloid and Interface Science 2017 Volume 487() pp:281-288
Publication Date(Web):1 February 2017
DOI:10.1016/j.jcis.2016.10.044
BaLuF5:Ce,Tb,Eu(Sm) submicrospheres were synthesized via an ILs/ethylene glycol(EG) two-phase system. The crystalline phase, size, morphology, and luminescence properties were characterized using powder X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectra. The results show that 1-methyl-3-octylimidazolium hexafluorophosphate ([Omim]PF6) was used as fluoride source and capping agent to tune morphology and size of the crystals. The formation mechanism has been supposed. Under the excitation of ultraviolet, the BaLuF5:5%Ce3+,5%Tb3+, BaLuF5:Eu3+, and BaLuF5:5%Ce3+,5%Sm3+ exhibit green and red emission, which was derived from Tb3+, Eu3+, and Sm3+ emission. When codoping Ce3+, Tb3+, Sm3+ or Eu3+ together, multi-color emission can be realized. Furthermore, this synthetic route may have potential applications for fabricating other lanthanide fluorides.
Co-reporter:Pingchuan Ma, Yanhua Song, Bo Yuan, Ye Sheng, Chengyi Xu, Haifeng Zou, Keyan Zheng
Ceramics International 2017 Volume 43(Issue 1) pp:60-70
Publication Date(Web):January 2017
DOI:10.1016/j.ceramint.2016.08.161
A series of Tb3+ or/and Bi3+ doped BaAl2Si2O8 phosphors were synthesized via solid-state method. The structure, luminescence properties and thermal stability were investigated. The optimum concentrations of Bi3+ and Tb3+ were 1.5 mol% and 7 mol%, respectively. Furthermore, BaAl2Si2O8:0.015Bi3+ and BaAl2Si2O8:0.07Tb3+ phosphors emitted blue and green light and the emission color of BaAl2Si2O8:Bi3+, Tb3+ could be tuned from blue to green through the energy transfer. This energy transfer from Bi3+ to Tb3+ was confirmed and investigated by photoluminescence spectrum and decay lifetime. With constantly increasing Tb3+ concentrations, the energy transfer efficiency from Bi3+ to Tb3+ in BaAl2Si2O8 host increased gradually and reached as high as 86.54%, the quantum yield was about 44.26%. The energy transfer mechanism (Bi3+-Tb3+) was proved to be dipole–dipole mechanism. The Tb3+ emission intensity can be considerably enhanced when monitored at NUV (377 nm) by co-doping Bi3+ ion. Moreover, the phosphor of BaAl2Si2O8:0.015Bi3+, 0.07Tb3+ could exhibited strong green emission with good CIE chromaticity coordinate. The results indicate that BaAl2Si2O8:Tb3+, Bi3+ is a potential green emitting phosphor for the application in w-LEDs.
Co-reporter:Chengyi Xu;Yanhua Song;Hongxia Guan;Ye Sheng;Pingchuan Ma;Xiuqing Zhou;Zhan Shi
Physical Chemistry Chemical Physics 2017 vol. 19(Issue 33) pp:22197-22209
Publication Date(Web):2017/08/23
DOI:10.1039/C7CP02789C
A series of emission-tunable Na1−xAl1+2xSi1−2xO4:xCe3+/Tb3+/Dy3+ phosphors were synthesized via a high temperature solid-state reaction method. Luminescence properties, energy transfer from Ce3+ to Tb3+ or Dy3+ ions, color tuning and thermal stability were systematically investigated. Particularly, the charge compensating defect generated by doping of rare earth ions was remedied through Al3+ substituted Si4+. Meanwhile, the emission intensity was significantly improved. The presence and content of various elements were demonstrated through data combined with the crystallographic data from Rietveld refinements and the analysis of SEM and mapping for each element. The results indicated that this charge balance strategy was an effective method. The energy transfer from Ce3+ to Tb3+ and Dy3+ in the co-doped NaAlSiO4 (NAS) samples was deduced from the spectral overlap between the Ce3+ emission and Tb3+/Dy3+ excitation spectra, the photoluminescence spectra and the fluorescence decay curves. The energy transfer mechanisms of Ce3+ to Tb3+ and Dy3+ in the host were studied. And the emission hue can be tuned from blue to green and yellow by properly varying the ratio of Ce3+ and Tb3+/Dy3+. Additionally, the temperature-dependent photoluminescence of the as-prepared phosphors was investigated in detail. All these properties indicate that the developed phosphor may potentially be used as a single-component multicolor-emitting phosphor for UV light-emitting diodes.
Co-reporter:Yuexin Wang;Yanhua Song;Yi Li;Tingting Cui;Xiuqing Zhou;Ye Sheng;Keyan Zheng;Hongpeng You
New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 2) pp:709-716
Publication Date(Web):2017/01/16
DOI:10.1039/C6NJ03042D
LuVO4:Eu3+ nano/microcrystals with different morphologies/sizes including nanoparticles, nanosheets, nanodisks, nanoquadrangles, sub-microflakes, microspheres, and bulks were successfully synthesized by a mild solvothermal process using tartaric acid (TA) as the template. The amount of tartaric acid (TA) and the initial pH value play vital roles in controlling the morphologies of LuVO4 products. Besides, the reaction temperature was responsible for the generation of pure LuVO4 crystals in the presence of TA. Based on this, the possible formation mechanism of multi-morphologies was proposed. Furthermore, the dependence of luminescence performance on morphology has been discussed in detail. The LuVO4:Ln3+ (Ln = Tm3+, Er3+, Sm3+, Eu3+) nanoparticles show the characterized transition of Ln3+ and give bright blue, green, orange-red and red emission. Moreover, blue-green, green-yellow, pink, yellow-pink and white light can be obtained by adjusting the amount of doped Ln3+ ions and the corresponding concentrations of the LuVO4 host. This general and simple method may be of much significance in the synthesis of many other rare earth inorganic materials.
Co-reporter:Yi Li;Yuexin Wang;Yanhua Song;Xiuqing Zhou;Keyan Zheng;Ye Sheng
CrystEngComm (1999-Present) 2017 vol. 19(Issue 11) pp:1517-1527
Publication Date(Web):2017/03/13
DOI:10.1039/C7CE00018A
GdF3 with raisin-like particles, plates with dots in their centers, peanut-like particles and spherulite-like particles have been synthesized via a simple hydrothermal method with tartaric acid as an additive, by simply modulating the pH values and H2O/ethanol ratio of the system. The possible formation mechanisms of the particles obtained in mixed solvents and pure water are proposed based on a series of time-dependent experiments. Both hexagonal and orthorhombic phases were obtained and the factors influencing the phase transitions are discussed in detail. The luminescence properties prove that the GdF3 particles are excellent host lattices. Under ultraviolet excitation, GdF3:Eu3+ particles exhibit strong red emission corresponding to the 5D0 → 7F1 transition of the Eu3+ ions. Furthermore, the dependence of GdF3:Eu3+ luminescence performances on different morphologies and phases are discussed in the present work.
Co-reporter:Hongxia Guan, Ye Sheng, Chengyi Xu, Yunzhi Dai, Xiaoming Xie and Haifeng Zou
Physical Chemistry Chemical Physics 2016 vol. 18(Issue 29) pp:19807-19819
Publication Date(Web):24 Jun 2016
DOI:10.1039/C6CP03989H
A series of Dy3+, Tb3+, Eu3+ singly or doubly or triply doped GdF3 phosphors were synthesized by a glutamic acid assisted one-step hydrothermal method. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and photoluminescence (PL) spectroscopy. The results show that the synthesized samples are all pure GdF3. The obtained samples have a peanut-like morphology with a diameter of about 270 nm and a length of about 600 nm. Under UV excitation, GdF3:Dy3+, GdF3:Tb3+ and GdF3:Eu3+ samples exhibit strong blue, green and red emissions, respectively. By adjusting their relative doping concentrations in the GdF3 host, the different color hues of green and red light are obtained by co-doped Dy3+, Tb3+ and Tb3+, Eu3+ ions in the GdF3 host, respectively. Besides, there exist two energy transfer pairs in the GdF3 host: (1) Dy3+ → Tb3+ and (2) Tb3+ → Eu3+. More significantly, in the Dy3+, Tb3+, and Eu3+ tri-doped GdF3 phosphors, white light can also be achieved upon excitation of UV light by adjusting the doping concentration of Eu3+. In addition, the obtained samples also exhibit paramagnetic properties at room temperature (300 K) and low temperature (2 K). It is obvious that multifunctional Dy3+, Tb3+, Eu3+ tri-doped GdF3 materials including tunable multicolors and intrinsic paramagnetic properties may have potential applications in the field of full-color displays.
Co-reporter:Meiqi Chang, Ye Sheng, Yanhua Song, Keyan Zheng, Xiuqing Zhou and Haifeng Zou
RSC Advances 2016 vol. 6(Issue 57) pp:52113-52121
Publication Date(Web):20 May 2016
DOI:10.1039/C6RA07509F
One-dimensional TiO2:xEu3+ nanofibers were fabricated via electrospinning and subsequent calcination. The as-spun nanofibers were calcined at 600, 700, 800 and 900 °C for 5 h at a heating rate of 1 °C min−1 and the concentrations of Eu3+ dopants were varied from 17 mol% to 20 mol%. The TiO2:19 mol% Eu3+ nanofibers which calcined at 700 °C (optimum condition) were investigated by thermogravimetric-differential thermal analysis (TG-DTA), X-ray diffraction (XRD), X-ray photo-electronic spectroscopy (XPS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence (PL) excitation and emission spectra. In this article, we have discussed the effect of different calcination temperature on fiber diameter and photoluminescence properties of europium doped titania (TiO2:xEu3+) nanofibers. The possible formation mechanism of TiO2:x mol% Eu3+ nanofibers was also discussed. The spectral characteristics and Eu–O ligand behavior were discussed through Judd–Ofelt parameters such as radiative transition probability (ARAD), radiative lifetime (τrad), branching ratio (β0J) and intensity parameters (Ω2, Ω4). Furthermore, the TiO2:19 mol% Eu3+ nanofibers exhibit strong red luminescence that corresponds to the 5D0–7F2 transition (612 nm) of the Eu3+ ions under the excitation of ultraviolet light.
Co-reporter:Bo. Yuan;Yanhua Song;Ye. Sheng;Keyan Zheng;Qisheng Huo;Xuechun Xu
Luminescence 2016 Volume 31( Issue 2) pp:453-461
Publication Date(Web):
DOI:10.1002/bio.2981
Abstract
A series of Ca2Mg0.25Al1.5Si1.25O7:Ce3+/Eu2+/Tb3+ phosphors was been prepared via a conventional high temperature solid-state reaction and their luminescence properties were studied. The emission spectra of Ca2Mg0.25Al1.5Si1.25O7:Ce3+,Eu2+ and Ca2Mg0.25Al1.5Si1.25O7:Ce3+,Tb3+ phosphors show not only a band due to Ce3+ ions (409 nm) but also as a band due to Eu2+ (520 nm) and Tb3+ (542 nm) ions. More importantly, the effective energy transfer from Ce3+ to Eu2+ and Tb3+ ions was confirmed and investigated by emission/excitation spectra and luminescent decay behaviors. Furthermore, the energy level scheme and energy transfer mechanism were investigated and were demonstrated to be of resonant type via dipole–dipole (Ce3+ to Eu2+) and dipole–quadrupole (Ce3+ to Tb3+) reactions, respectively. Under excitation at 350 nm, the emitting color could be changed from blue to green by adjusting the relative doping concentration of Ce3+ and Eu2+ ions as well as Ce3+ and Tb3+ ions. The above results indicate that Ca2Mg0.25Al1.5Si1.25O7:Ce3+,Eu2+/Tb3+ are promising single-phase blue-to-green phosphors for application in phosphor conversion white-light-emitting diodes. Copyright © 2015 John Wiley & Sons, Ltd.
Co-reporter:Hui Zhang;Ye Sheng;Xiuqing Zhou;Jie Chen;Zhan Shi;Xuechun Xu
European Journal of Inorganic Chemistry 2015 Volume 2015( Issue 11) pp:1871-1876
Publication Date(Web):
DOI:10.1002/ejic.201403204
Abstract
SiO2:Eu3+ nanowires were prepared by a solvothermal method followed by subsequent calcination and acid washing processes. The structure, morphology, and properties of the products were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and photoluminescence (PL) spectroscopy. The results indicated that the obtained SiO2:Eu3+ nanowires exhibited red emission under ultraviolet light excitation and may have potential applications in optical and biological areas. In addition, a possible formation process for the SiO2:Eu3+ nanowires is proposed in detail.
Co-reporter:Meiqi Chang, Yanhua Song, Hongguang Zhang, Ye Sheng, Keyan Zheng, Xiuqing Zhou and Haifeng Zou
RSC Advances 2015 vol. 5(Issue 73) pp:59314-59319
Publication Date(Web):24 Jun 2015
DOI:10.1039/C5RA07525D
Uniform TiO2:Eu3+ spindlelike nanorods have been successfully prepared by a hydrothermal assisted sol–gel process with ethanediamine (ED) as the shape controller. A possible formation mechanism and luminescent properties were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) and kinetic decays. Site-selective spectroscopy was used to research into sites of Eu3+ in TiO2 lattice at 10 K, which identifies two kinds of sites of Eu3+ in TiO2 nanocrystals. One is located in the distorted lattice sites near the surface, and the other is situated in lattice sites with ordered crystalline environment. Moreover, the luminescence decay curve of products further proved the existence of multiple sites of Eu3+ ions in TiO2 nanocrystals.
Co-reporter:Hongguang Zhang, Yanhua Song, Ye Sheng, Haoxi Li, Zhan Shi, Xuechun Xu, Haifeng Zou
Ceramics International 2015 Volume 41(Issue 1) pp:247-252
Publication Date(Web):January 2015
DOI:10.1016/j.ceramint.2014.08.065
Three dimensional (3D) TiO2 core–shell microspheres were successfully synthesized by a one-step hydrothermal method using ethylenediaminetetraacetic acid (EDTA) as the assistant agent. The sample was characterized by XRD, EDX, SEM, TEM, and BET. The photocatalytic activity of TiO2 core–shell microspheres for the degradation of methyl orange (MO) aqueous solution was measured by UV–vis absorption spectroscopy. The XRD result shows that the TiO2 core–shell microspheres are crystalline without further sintering treatment. Furthermore, the core–shell microspheres exhibit higher photocatalytic activity than that of commercial TiO2 (Degussa P25) for oxidation of MO under UV light irradiation. The enhanced photocatalytic activity is due to the high BET surface area of the sample, which might possess more surface reaction sites and can adsorb and transport more dye molecules.
Co-reporter:Bo Yuan, Ye Sheng, Yanhua Song, Keyan Zheng, Xiuqing Zhou, Xuechun Xu, Haifeng Zou
Journal of Alloys and Compounds 2015 Volume 644() pp:82-90
Publication Date(Web):25 September 2015
DOI:10.1016/j.jallcom.2015.04.192
•Ca2Mg0.75Al0.5Si1.75O7:Ln (Ln = Ce3+, Dy3+, Eu3+, Sm3+) are blue, white and red novel phosphors.•Their luminescence properties and fluorescence lifetimes are measured and investigated.•A series of white LED prototypes were fabricated and tested under the forward bias current.•These phosphors have great application value in WLEDs as blue, white and red phosphors.A series of Ca2Mg0.75Al0.5Si1.75O7:Ln (Ln = Ce3+, Dy3+, Eu3+, Sm3+) phosphors were synthesized by conventional high temperature solid state reaction. Their luminescent properties, color chromaticity and application in UV white LED were investigated. The research showed that the CIE chromatic coordinates of the phosphors are in the blue (Ce3+ doped sample), white (Dy3+doped sample) and red (Eu3+ and Sm3+ doped sample) regions, respectively. Furthermore, blue, red and white light-emitting diode (LED) prototypes were fabricated using as-prepared phosphors and UV chips. In addition, the luminescence efficiency, CIE chromaticity coordinates, correlated color temperature (CCT) and color rendering index (CRI) of these LED prototypes were exhibited. The results indicated that these phosphors were of potential application in UV white LED.
Co-reporter:Hongguang Zhang, Ye Sheng, Xiuqing Zhou, Yanhua Song, Zhan Shi, Xuechun Xu, Haifeng Zou
Powder Technology 2015 Volume 274() pp:193-198
Publication Date(Web):April 2015
DOI:10.1016/j.powtec.2015.01.024
•TiO2:Eu3 + microspheres were successfully synthesized by hydrothermal method.•TiO2:Eu3 + microspheres are loose and porous with flower-like structure.•Mechanism for the formation of TiO2:Eu3 + flower-like microspheres was proposed.•TiO2:Eu3 + microspheres exhibited excellent red emission under UV light excitation.Self-assembled 3D flower-like TiO2:Eu3 + microspheres have been synthesized by a simple hydrothermal method and crystallized by subsequent heat treatments at elevated temperatures. The as-prepared samples are loose and porous with flower-like structure, and the subunits are irregularly shaped nanosheets. A possible growth mechanism is proposed for the 3D flower-like TiO2:Eu3 + microspheres, and it was found that the synergistic effect of citric acid (H3Cit), ethanediamine (En) and hydrofluoric acid (HF) is of crucial importance for the controllable fabrication of TiO2:Eu3 + flower-like hierarchical structures. Furthermore, the calcined flower-like TiO2:Eu3 + hierarchical microspheres exhibit excellent red emission corresponding to the 5D0–7F2 transition of the Eu3 + ions under UV light excitation.
Co-reporter:Hongguang Zhang;Ye Sheng;Keyan Zheng;Xiuqing Zhou;Zhan Shi;Xuechun Xu
European Journal of Inorganic Chemistry 2014 Volume 2014( Issue 21) pp:3305-3311
Publication Date(Web):
DOI:10.1002/ejic.201402062
Abstract
Highly crystalline and uniform TiO2:Eu3+ spindlelike nanorods have been successfully synthesized through a facile hydrothermal route with citric acid (H3Cit) and ethanediamine (en) as the assistant agents for the first time. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), and photoluminescence (PL) spectroscopy were utilized to characterize the samples. In the synthetic process, the dosages of ethanediamine and citric acid are important parameters that affect the morphology and size of the final products. A possible formation process of the samples has been proposed in detail. The existence of Eu3+ sites in the TiO2 nanorods was proved by site-selective spectroscopy. Furthermore, the TiO2:Eu3+ spindlelike nanorods exhibit bright red (Eu3+, 5D07F2) luminescence under ultraviolet (UV) excitation; therefore, they may find potential applications in fluorescent lamps and field-emission displays (FEDs).
Co-reporter:Xiaofei Qi, Yanhua Song, Ye Sheng, Hongguang Zhang, Huan Zhao, Zhan Shi, Haifeng Zou
Optical Materials 2014 Volume 38() pp:193-197
Publication Date(Web):December 2014
DOI:10.1016/j.optmat.2014.10.026
•TiO2:Eu3+ nanorods, nanoparticles and submicrospheres have been prepared through hydrothermal synthesis.•The acidic and alkaline conditions play an important role in the geometric morphologies of the final products.•The luminescence intensity of the TiO2:Eu3+ materials is strongly dependent on their morphology.Eu3+-doped TiO2 nanocrystals with three kinds of morphologies (nanorods, nanoparticles, and submicrospheres) have been successfully fabricated in cetyltrimethylammonium bromide (CTAB)/water/cyclohexane/n-pentanol reverse micelle by hydrothermal method for the first time and their photoluminescence (PL) properties have also been studied. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), FT-IR, and PL spectra were used to characterize the samples. The acidic and alkaline conditions of the microemulsion play an important role in determining the geometric morphologies of the final products. TiO2:Eu3+ with three different morphologies all exist only in anatase phase and show high luminescence intensity without further calcinations, which show its advantages of energy saving. The shape of emission spectra was independent of the morphologies of the products but the luminescence intensity of the TiO2:Eu3+ materials is strongly dependent on their morphology. The results show that TiO2:Eu3+ nanorods possess the strongest luminescence intensity among the three nanostructured samples.
Co-reporter:Weiwei Bao, Fengying Guo, Haifeng Zou, Shucai Gan, Xuechun Xu, Keyan Zheng
Powder Technology 2013 Volume 249() pp:220-224
Publication Date(Web):November 2013
DOI:10.1016/j.powtec.2013.08.001
•We synthesize alumina aerogels using oil shale ash as alumina source.•Alumina aerogels were modified by silylation and characterized.•After silylation, the surface property of alumina aerogels changed to hydrophobic.In this study, the hydrophobic alumina aerogels were successfully prepared using oil shale ash (OSA) as a new raw material. The process consisted of two stages, leaching of aluminum and hydrophobic modification. The effects of methyltrimethoxysilane (MTMS) and tetraethylorthosilicate (TEOS) used as surface modifying agents on the physicochemical properties of the alumina aerogels were investigated. The surface chemical group, thermal stability, structure properties and morphological features before and after modification were examined by Fourier transform infrared (FT-IR), Thermogravimetry–differential thermal analysis (TG–DTA), Brunauer–Emmett–Teller (BET) and Scanning electron microscope (SEM) techniques. The experimental results indicated that the obtained alumina aerogels without surface modification had ordered mesoporous structure and flaky morphology with average length of about 200–300 nm. After surface modified with MTMS, the surface property of alumina aerogels changed from hydrophilic to hydrophobic, meanwhile the morphology changed to catkin-like structure. The results obtained in this experiment prove that the OSA can be used to prepare hydrophobic alumina aerogels, which explores a new way for comprehensive utilization of OSA.
Co-reporter:Hongguang Zhang, Ye Sheng, Yanhua Song, Hongbo Li, Jing Huang, Keyan Zheng, Qisheng Huo, Xuechun Xu, Haifeng Zou
Powder Technology 2013 Volume 239() pp:403-408
Publication Date(Web):May 2013
DOI:10.1016/j.powtec.2013.02.010
Co-reporter:Jing Huang, Yanhua Song, Guowei Wang, Ye Sheng, Keyan Zheng, Hongbo Li, Hongguang Zhang, Qisheng Huo, Xuechun Xu, Haifeng Zou
Journal of Alloys and Compounds 2013 Volume 574() pp:310-315
Publication Date(Web):15 October 2013
DOI:10.1016/j.jallcom.2013.05.087
•Gd2O3:Eu3+ core–shell mirospheres were prepared successfully.•PVP play a significant role in the formation progress of core–shell structure.•The obtained core–shell microspheres exhibit excellent red-luminescent properties.Homogeneous and monodisperse Gd2O3:Eu3+ core–shell mirospheres have been successfully synthesized via a solvothermal method with polyvinylpyrrolidone (PVP) as surfactant, followed by a subsequent calcination process. The as-prepared products were characterized by various methods, including X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR), scanning electron microscopy (SEM), energy-dispersive spectrometer (EDS), trans-mission electron microscopy (TEM), selected area electron diffraction (SAED), high resolution transmission electron microscopy (HRTEM), and photoluminescence spectra (PL). The results show that the obtained Gd2O3:Eu3+ mirospheres with a core–shell structure are uniform in size and distribution, and they have diameters of ∼350 nm, the core diameters of ∼150 nm, and the shell thicknesses of ∼45 nm. Under ultraviolet (UV) excitation, the corresponding Gd2O3:Eu3+ products exhibit strong red emission corresponding to the 5D07F2 transition of the Eu3+ ions, which might find potential applications in the fields such as light-emitting phosphors, advanced flat panel displays, or biological labeling.
Co-reporter:Hongbo Li, Keyan Zheng, Ye Sheng, Yanhua Song, Hongguang Zhang, Jing Huang, Qisheng Huo, Haifeng Zou
Optics & Laser Technology 2013 Volume 49() pp:33-37
Publication Date(Web):July 2013
DOI:10.1016/j.optlastec.2012.12.007
Uniform TiO2:Eu3+ nanobelts have been successfully prepared by a simple hydrothermal method without any surfactant, catalyst or template. The as-synthesized products were characterized by X-ray diffraction, transmission electron microscopy and Fourier Transform Infrared Spectrophotometry. X-ray diffraction results demonstrate that all the diffraction peaks of the samples annealed at 500 °C can be well indexed to the pure anatase-phase TiO2. Under ultraviolet excitation, TiO2:Eu3+ nanobelts exhibit red emission corresponding to the 5D0–7F2 transition of the Eu3+ ions, and the photoluminescence intensity is the strongest when calcination temperature is 500 °C. It is expected that the TiO2:Eu3+ nanobelts can be used as novel semiconductor luminescence materials.Highlights► Uniform TiO2:Eu3+ nanobelts have been prepared by a simple hydrothermal method. ► Crystallinity, morphology and photoluminescence of TiO2:Eu3+nanobelts change with the annealing temperature. ► PL intensity achieves the strongest when calcination temperature is at 500 °C.
Co-reporter:Hongbo Li, Keyan Zheng, Xuechun Xu, Huan Zhao, Yanhua Song, Ye Sheng, Qisheng Huo, Haifeng Zou
Powder Technology 2012 Volume 228() pp:277-283
Publication Date(Web):September 2012
DOI:10.1016/j.powtec.2012.05.032
Uniform TiO2:Eu3+ nanorods and spindle-shaped nanoparticles have been successfully prepared through simple calcination and two-step hydrothermal processes using titanate as the precursor. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectrophotometer, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence spectra (PL) were used to characterize these nanoparticles. On the basis of X-ray diffraction result, it can be assumed that the as-obtained precursors have the structure formula of titanate (H2Ti2O5·H2O). The as-formed nanotube precursors could transform to anatase TiO2:Eu3+ from nanotubes to nanorods and spindle-shaped nanoparticles with the calcination and hydrothermal processes. Under UV light excitation, both the TiO2:Eu3+ nanorods and spindle-shaped nanoparticles exhibit the strong red emission corresponding to the 5D0–7F2 transition of the Eu3+ ions. In addition, the luminescence properties of the as-obtained samples are dependent on the defects on the surface, leading to stronger luminescence intensity.Picture illustration for the formation process of TiO2:Eu3+ spindle-shaped nanoparticles.Highlights► TiO2:Eu3+ spindle-shaped nanoparticles were prepared from tinatate nanobelts. ► The formation mechanism has been proposed. ► Luminescence intensity of the spindle-shaped nanoparticles exhibits red emission.
Co-reporter:Yanhua Song, Xuechun Xu, Haifeng Zou, Ye Sheng, Hongpeng You
Journal of Alloys and Compounds 2012 Volume 513() pp:86-90
Publication Date(Web):5 February 2012
DOI:10.1016/j.jallcom.2011.09.090
MSi2O2−δN2+2/3δ:Eu2+ (M = Sr, Ba) phosphors were prepared through a two-step solid state reaction. XRD results reveal that the samples are nitrogen-rich phase. The photoluminescence results show that the MSi2O2−δN2+2/3δ:Eu (M = Sr, Ba) phosphors can be excited by UV and blue light. The critical concentrations of Eu2+ are 5 mol% and 4 mol% for MSi2O2−δN2+2/3δ:Eu (M = Sr, Ba), respectively. With an increase of the Eu2+-concentration, the emission color of SrSi2O2−δN2+2/3δ:Eu can be tuned from green to yellow. Under the excitation of low voltage electron beams (1–3 kV), the MSi2O2−δN2+2/3δ:Eu (M = Sr, Ba) phosphors exhibit green and cyan emission, respectively. The emission intensity increases with the increasing of accelerating voltage and filament current. Due to the excellent stability, good CIE chromaticity and high color purity, MSi2O2−δN2+2/3δ:Eu (M = Sr, Ba) phosphors may have potential application in the field emission displays.Highlights► MSi2O2−δN2+2/3δ (M = Sr, Ba):Eu2+ with nitrogen-rich phase were synthesized by two-step solid state reaction method. ► With the increase of the Eu2+-concentration, the photoluminescence color of SrSi2O2−δN2+2/3δ:Eu2+ can be tuned from green to yellow. ► Under the excitation of low voltage cathode rays, MSi2O2−δN2+2/3δ:Eu2+(M = Sr, Ba) phosphors exhibit green and cyan emissions, respectively. ► The good stability and high color purity for MSi2O2−δN2+2/3δ:Eu2+ (M = Sr, Ba) phosphors make them have potential applications in FED area.
Co-reporter:Hongbo Li, Ye Sheng, Huan Zhao, Yanhua Song, Fei Gao, Qisheng Huo, Haifeng Zou
Materials Research Bulletin 2012 47(12) pp: 4322-4328
Publication Date(Web):
DOI:10.1016/j.materresbull.2012.09.010
Co-reporter:Hongbo Li;Huan Zhao;Ye Sheng;Jing Huang;Yanhua Song
Journal of Nanoparticle Research 2012 Volume 14( Issue 6) pp:
Publication Date(Web):2012 June
DOI:10.1007/s11051-012-0947-9
TiO2:Eu3+ nanorods and nanobelts were successfully prepared through a simple hydrothermal method followed by a subsequent calcination process. On the basis of X-Ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy results, it can be assumed that the precursors have the structural formula of titanate (H2Ti2O5·H2O). The morphologies of the precursors are nanobelts and nanotubes. However, the nanobelts could transform to anatase TiO2 with the same morphology, while the nanotubes modulate from nanotubes to nanorods after an annealing process. Both the TiO2:Eu3+ nanorods and nanobelts exhibit strong red emission corresponding to the 5D0–7F2 transition of the Eu3+ ions under UV light excitation. However, TiO2:Eu3+ nanobelts showed higher emission intensity than that of the nanorods; the reason is that the nanobelts have less defects.
Co-reporter:Ye Sheng;Xuechun Xu;Wenyong Jiang;Yanhua Song
Journal of Surfactants and Detergents 2012 Volume 15( Issue 4) pp:393-398
Publication Date(Web):2012 July
DOI:10.1007/s11743-012-1329-0
Oxidized cornstarch, which is only composed of carbon, hydrogen and oxygen elements, was used as a builder in detergent formulations to reduce the hardness of water. Therefore, the calcium binding capacity of these oxidized cornstarch samples was tested and the relative detersive efficiency of the self-made detergent with oxidized cornstarch builder was also evaluated. The results show that higher Ca2+ binding capacities 104.5 mg/g can be obtained when the synthesis is carried out at 100 °C for 3 h in conjunction with the addition of 21 g NaOH. The detersive efficiency can reach 1.28 which is equivalent to the other detergent powders. In addition, the biodegradability of the oxidized cornstarch was judged as being adequate by the China National Center for Quality Supervision and Test of Plastic Products. Compared with the traditional detergent builders, the oxidized cornstarch is water-soluble, environmentally friendly, and cheap, with an equivalent performance to traditional detergent builders.
Co-reporter:Hongbo Li, Ye Sheng, Hongguang Zhang, Jiwei Xue, Keyan Zheng, Qisheng Huo, Haifeng Zou
Powder Technology 2011 Volume 212(Issue 2) pp:372-377
Publication Date(Web):10 October 2011
DOI:10.1016/j.powtec.2011.06.019
TiO2 nanotubes doped with Eu3+ ions have been fabricated by a simple hydrothermal process. The formation mechanism of TiO2:Eu3+ nanotubes is proposed in detail. The nanotubes are evolved from the rolling up of the anatase sheets, which was verified by characterizations using the X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscope (SEM). Compared with the TiO2:Eu3+ nanocrystals, TiO2:Eu3+ nanotubes exhibit considerably stronger photoluminescence (PL) under the excitation of 393 nm. Furthermore, the PL intensity increases with the increasing of Eu3+ concentration in TiO2 nanotubes, and concentration quenching occurs when Eu3+ concentration exceeds 2.0 mol%. In addition, the luminescent lifetime of the TiO2:Eu3+ nanotubes is also examined. It is expected that the TiO2:Eu3+ nanotubes can be used as novel semiconductor luminescence materials.TiO2 nanotubes doped with Eu3+ have been fabricated by a simple hydrothermal process. The mechanism of the formation process of Eu3+-doped TiO2 nanotubes was proposed in detail.Highlights► TiO2:Eu3+ nanotubes have been fabricated by hydrothermal process. ► The nanotubes are composed of sheets containing a few layers. ► The best doping concentration is 2 mol%. ► The PL intensity is higher than Eu3+-doped TiO2 nanoparticles.
Co-reporter:Ye Sheng, Lei Zhang, Hongbo Li, Jiwei Xue, Keyan Zheng, Nan Guo, Qisheng Huo, Haifeng Zou
Thin Solid Films 2011 Volume 519(Issue 22) pp:7966-7970
Publication Date(Web):1 September 2011
DOI:10.1016/j.tsf.2011.05.009
Nanometer TiO2 thin films doped with different concentration of Tb were prepared by sol–gel method and characterized by X-ray diffraction (XRD), thermogravimetry–differential thermal analysis (TG-DTA), transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. XRD results show preferentially oriented (101) anatase films. TEM image indicates that the TiO2 films consist of TiO2 grains with diameter about 15 nm. Under room temperature, strong visible luminescence of Tb3+ ions due to intra-4f shell transitions are obtained and the PL intensity is found to have a well matching relation with the doping concentration of Tb3+ ions. Concentration quenching of PL occurs when Tb3+ concentration exceeds a certain value (9.2 mol%). Furthermore, the luminescence intensity is improved obviously after co-doping with Gd3+ ions because of the sensitization effects of Gd3+ ions to Tb3+ ions in TiO2 system. The energy transfer mechanism from TiO2 and Gd3+ ions to Tb3+ ions was proposed.
Co-reporter:Yanhua Song ; Haifeng Zou ; Ye Sheng ; Keyan Zheng ;Hongpeng You
The Journal of Physical Chemistry C 2011 Volume 115(Issue 40) pp:19463-19469
Publication Date(Web):September 1, 2011
DOI:10.1021/jp203903b
Sodium lanthanide sulfate NaLn(SO4)2·H2O (Ln = Y, La to Yb) nano/microcrystals with multiform morphologies were successfully synthesized by a facile and effective hydrothermal method. The photoluminescence properties of the Ce3+ and Tb3+ single-doped as well as the Ce3+–Tb3+ codoped NaY(SO4)2·H2O microsheaves were characterized. The results reveal that the existence of the Ce3+ ions can dramatically enhance the emission intensity of the Tb3+ ions, due to an efficient energy transfer from the Ce3+ to the Tb3+ ions. The critical energy-transfer distance between the Ce3+ and the Tb3+ ions was calculated by methods of concentration quenching and spectral overlapping. Analysis and calculation reveal that the dipole–quadrupole interaction should be mainly responsible for the energy transfer.
Co-reporter:Weiwei BAO, Lu LIU, Haifeng ZOU, Shucai GAN, Xuechun XU, Guijuan JI, Guimei GAO, Keyan Zheng
Chinese Journal of Chemical Engineering (September 2013) Volume 21(Issue 9) pp:974-982
Publication Date(Web):1 September 2013
DOI:10.1016/S1004-9541(13)60529-7
Na-A zeolite was synthesized using oil shale ash (OSA), which is a solid by-product of oil shale processing. The samples were characterized by various techniques, such as scanning electron microscopy, X-ray diffraction and Brunauer Emmet Teller method. The batch isothermal equilibrium adsorption experiments were performed to evaluate the ability of Na-A zeolite for removal of Cu (II) from aqueous solutions. The effects of operating parameters, such as concentration of copper solutions, adsorbent dosages, pH value of solutions and temperature, on the adsorption efficiency were investigated. The equilibrium adsorption data were fitted with Langmuir and Freundlich models. The maximum adsorption capacity of Na-A zeolite obtained from the Langmuir adsorption isotherm is 156.7 mg·g−1 of Cu (II). The increase of pH level in the adsorption process suggests that the uptake of heavy metals on the zeolite follows an ion exchange mechanism. The batch kinetic data fit the pseudo-second order equation well. The thermodynamic parameters, such as changes in Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS), are used to predict the nature of the adsorption process. The negative ΔG values at different temperatures confirm that the adsorption processes are spontaneous.
Co-reporter:Hongxia Guan, Ye Sheng, Chengyi Xu, Yunzhi Dai, Xiaoming Xie and Haifeng Zou
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 29) pp:NaN19819-19819
Publication Date(Web):2016/06/24
DOI:10.1039/C6CP03989H
A series of Dy3+, Tb3+, Eu3+ singly or doubly or triply doped GdF3 phosphors were synthesized by a glutamic acid assisted one-step hydrothermal method. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and photoluminescence (PL) spectroscopy. The results show that the synthesized samples are all pure GdF3. The obtained samples have a peanut-like morphology with a diameter of about 270 nm and a length of about 600 nm. Under UV excitation, GdF3:Dy3+, GdF3:Tb3+ and GdF3:Eu3+ samples exhibit strong blue, green and red emissions, respectively. By adjusting their relative doping concentrations in the GdF3 host, the different color hues of green and red light are obtained by co-doped Dy3+, Tb3+ and Tb3+, Eu3+ ions in the GdF3 host, respectively. Besides, there exist two energy transfer pairs in the GdF3 host: (1) Dy3+ → Tb3+ and (2) Tb3+ → Eu3+. More significantly, in the Dy3+, Tb3+, and Eu3+ tri-doped GdF3 phosphors, white light can also be achieved upon excitation of UV light by adjusting the doping concentration of Eu3+. In addition, the obtained samples also exhibit paramagnetic properties at room temperature (300 K) and low temperature (2 K). It is obvious that multifunctional Dy3+, Tb3+, Eu3+ tri-doped GdF3 materials including tunable multicolors and intrinsic paramagnetic properties may have potential applications in the field of full-color displays.
