Co-reporter:Hekai Zhu, Minghao Fang, Zhaohui Huang, Yan’gai Liu, Kai Chen, Ming Guan, Chao Tang, Lina Zhang, Meng Wang
Applied Surface Science 2017 Volume 393() pp:348-356
Publication Date(Web):30 January 2017
DOI:10.1016/j.apsusc.2016.10.038
Highlights
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Novel Cr doped A2ZnTiO6 (A = Pr, Gd) photocatalysts were successfully synthesized.
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The light absorbance and photocatalytic activity are enhanced through Cr doping.
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The photocatalytic reaction mechanism of these photocatalyst was investigated.
Co-reporter:Meng Wang, Minghao Fang, Xin Min, Zhaohui Huang, Chao Tang, Yan'gai Liu, Xiaowen Wu
Chemical Physics Letters 2017 Volume 686(Volume 686) pp:
Publication Date(Web):16 October 2017
DOI:10.1016/j.cplett.2017.08.029
•NaNbxTa1−xO3 perovskites were synthesized via Molten salt method.•The NaNbxTa1−xO3 perovskites exhibited excellent photodegradation efficiencies for RhB.•The NaNbxTa1−xO3 perovskites exhibited excellent performance for the photocatalytic production of hydrogen.NaNbxTa1−xO3 perovskite photocatalysts with cubic microstructures were synthesized by the molten salt method. Furthermore, the photocatalysts were characterized in detail by XRD, SEM, TEM, XPS, PL. SEM results indicated that the added Nb significantly affects the microstructure. XPS results confirmed the presence of the Nb5+ dopant in NaNbxTa1−xO3. Compared to NaTaO3, the catalyst doped with Nb significantly affected the photocatalytic production of hydrogen in an aqueous solution and the photocatalytic degradation of RhB under UV light irradiation. NaNb0.5Ta0.5O3 exhibited the best activity for the photocatalytic degradation of RhB as well as excellent performance for the photocatalytic production of hydrogen.A series of NaNbxTa1−xO3 perovskite photocatalysts were synthesized via molten salt method. The optimum amount of Nb significantly improved photocatalytic activity because of the enhanced separation efficiency of the photogenerated electron–hole pairs. NaNb0.5Ta0.5O3 exhibited the best activity for the photocatalytic degradation of RhB as well as excellent performance for the photocatalytic production of hydrogen.Download high-res image (54KB)Download full-size image
Co-reporter:Yushuai Xu;Kai Huang;Gang Ou;Hao Tang;Hehe Wei;Qingyun Zhang;Jianghong Gong;Hui Wu
RSC Advances (2011-Present) 2017 vol. 7(Issue 30) pp:18539-18544
Publication Date(Web):2017/03/24
DOI:10.1039/C7RA01683B
In order to realize the oxygen evolution reaction (OER) with high efficiency on a large scale, a facile method has been created to fabricate NiO/Ni nanosheets by repeated size reduction and thermal oxidation on the surface. By using ultrathin Ni nanosheets with thicknesses of around 4 nm and different temperatures of thermal treatment, tunable oxidation of the metallic nanosheets was achieved. This was proven to have a great impact on the catalysts' electrical conductivity and activity. The NiO/Ni two-dimensional (2D) nano-metal catalyst prepared at 250 °C possesses a potential of 1.59 V (vs. RHE) at the current density of 100 mA cm−2 in 1 M KOH solution, and still exhibits a high performance after 15 000 cycles. Furthermore, the enhanced electrical conductivity and exposure of active sites contribute to a kinetically low-cost process, resulting in a Tafel slope of 51 mV dec−1. The repeated folding and calendering method is a mature industrial manufacturing procedure, and therefore this creative repeated size reduction and thermal oxidation production process for oxide/metal nanosheets has the potential to be extended to various kinds of metal materials that could be used to produce electrocatalysts in high yields.
Co-reporter:Ruilong Wen, Xiaoguang Zhang, Yaoting Huang, Zhaoyu Yin, Zhaohui Huang, Minghao Fang, Yan’gai Liu, Xiaowen Wu
Energy and Buildings 2017 Volume 139(Volume 139) pp:
Publication Date(Web):15 March 2017
DOI:10.1016/j.enbuild.2017.01.025
In this study, the fatty acid eutectics (capric acid (CA) and lauric acid (LA) eutectics) were impregnated into the expanded perlite (EP) and expanded vermiculite (EVM) to form the two kinds of composite phase change material (PCM). The chemical structure, crystalloid phase were determined by the Fourier transformation infrared spectroscope, X-ray diffractometer. The results show that the eutectics with the EP and EVM do not undergo a chemical reaction and only undergo a physical combination. The SEM results proved that eutectics are well adsorbed in the porous structure of the EP and EVM. The thermal properties were determined by the differential scanning calorimeter (DSC). The DSC result shows that the melting temperatures and latent heat values of the PCMs are in the range of about 21–23 °C and 81–117 J/g. The maximum impregnation ratio of fatty acid eutectics into EP and EVM were 82.93% and 57.48%. The thermal cycling test proves that the composites have good thermal reliability. TG analysis revealed that the composite PCMs had high thermal durability property above their working temperature ranges. Besides, thermal conductivity of the CA-LA/EP and CA-LA/EVM was increased approximately as 89.14% and 87.41% by adding 5 wt.% expanded graphite (EG). It is envisioned that the prepared shape-stabilized PCMs have considerable potential for developing their roles in thermal energy storage system.
Co-reporter:Shunqin Luo, Chao Tang, Zhaohui Huang, Chen Liu, Jiawei Chen, Minghao Fang
Ceramics International 2016 Volume 42(Issue 14) pp:15780-15786
Publication Date(Web):1 November 2016
DOI:10.1016/j.ceramint.2016.07.043
Abstract
In this study, bismuth oxyiodide/titanium dioxide (BiOI/TiO2) heterostructures with different molar ratios of Bi and Ti were synthesized by electrospinning and hydrothermal methods. The samples thus synthesized were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, X-ray photoelectron spectroscopy, and ultraviolet–visible diffuse reflectance spectroscopy. The results confirmed the presence of the BiOI/TiO2 heterojunction with Bi/Ti molar ratios of 0.20–1 by electrospinning and hydrothermal methods. Photocatalytic activity was also evaluated by the degradation of methylene blue (MB) under visible-light irradiation. The 80% BiOI/TiO2 heterostructure exhibited the best photocatalytic activity for the degradation of MB under visible-light irradiation.
Co-reporter:Hekai Zhu, Minghao Fang, Zhaohui Huang, Yan’gai Liu, Kai Chen, Xin Min, Yuanjie Mao, Meng Wang
Journal of Luminescence 2016 Volume 172() pp:180-184
Publication Date(Web):April 2016
DOI:10.1016/j.jlumin.2015.12.021
•Novel Li2Mg2 (WO4)3:Eu3+ phosphor was synthesized by solid state reaction.•The phosphors show dominant emission peak at 620 nm upon excitation at 398 nm.•The phosphors behave a relatively good thermal quenching effect.•CIE coordinates of the phosphor was measured as (0.678, 0.322).A series of novel Eu3+ doped tungstate Li2Mg2 (WO4)3 red phosphors were successfully synthesized by a solid-state reaction method. The phase structure, photoluminescence properties and thermal stability of the phosphor were investigated in detail. The Li2Mg2 (WO4)3:Eu3+ phosphors show dominant emission peak at 620 nm (5D0→7F2 transition) upon the strongest excitation at 398 nm (7F0→5L6 transition). The optimal doping concentration of Eu3+ is determined to be 0.06 mol in order to obtain the maximum emission intensity. The dependence of the emission intensity on temperature denominates that Li2Mg2 (WO4)3:Eu3+ phosphor has a relatively good thermal quenching effect. The Commission Internationale del’Eclairage coordinates was measured as (0.678, 0.322) with high color purity, being close to the National Television Standard Committee system standard for red chromaticity (0.670, 0.330). The above studies indicate that Li2Mg2 (WO4)3:Eu3+ is a promising candidate as the red phosphor for near ultraviolet-based white LEDs application.
Co-reporter:Yao Xie, Zhaohui Huang, Zhijie Zhang, Xiaoguang Zhang, Ruilong Wen, Yangai Liu, Minghao Fang, Xiaowen Wu
Applied Surface Science 2016 Volume 389() pp:56-66
Publication Date(Web):15 December 2016
DOI:10.1016/j.apsusc.2016.07.088
Highlights
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High contents of rhombic dodecahedral Ag3PO4 photocatalysts are prepared.
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Excessive EG can destroy the morphology of Ag3PO4 in synthesis process.
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The rhombic dodecahedral Ag3PO4 exhibits high surface energy.
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High surface energy implies high photocatalytic activity.
Co-reporter:Bo Tan, Zhaohui Huang, Zhaoyu Yin, Xin Min, Yan'gai Liu, Xiaowen Wu and Minghao Fang
RSC Advances 2016 vol. 6(Issue 19) pp:15821-15830
Publication Date(Web):29 Jan 2016
DOI:10.1039/C5RA25685B
A shape-stabilized composite phase change material (ss-CPCM) comprising polyethylene glycol (PEG) and porous carbon was prepared by absorbing PEG into porous carbon, assisted by ultrasound. In the composite, PEG served as a phase change material for thermal energy storage, and the porous carbon, which was prepared from fresh potato via freeze drying followed by heat treatment, was used as an absorbent that also acted as the supporting material. Various analytical techniques were used to investigate the chemical composition, microstructure, and thermal properties of the prepared PEG/porous carbon ss-CPCMs. Scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopic results indicated that PEG was well absorbed and encapsulated in the porous structure of the carbon and that there was no chemical reaction between them during the phase change process. The shape and exudation stability test results indicated that the PEG/porous carbon ss-CPCMs have excellent shape stability, compared to pristine PEG. The contact angle test suggested that the melting PEG has good level of wettability on the carbon so that melting PEG could be well protected from exudation in the porous carbon by surface tension effects, even if the temperature is higher than the melting point of PEG. Differential scanning calorimetric results showed that the PEG/porous carbon ss-CPCMs have considerable phase change enthalpies and thermal storage capabilities. In addition to this, the latent heats of ss-CPCMs increased with increasing contents of PEG in the composites, and the highest value was achieved when the amount of PEG was 50%. Moreover, the thermogravimetric analysis results showed that the composites had excellent thermal stabilities. Based on the above analyses, the prepared ss-CPCM with 50% PEG content proved to be a promising candidate for thermal energy storage applications.
Co-reporter:Meng Wang, Zhenglian Liu, Minghao Fang, Chao Tang, Zhaohui Huang, Yan'gai Liu, Xiaowen Wu, Yuanjie Mao
Solid State Sciences 2016 Volume 55() pp:1-7
Publication Date(Web):May 2016
DOI:10.1016/j.solidstatesciences.2016.02.002
•TiO2/g-C3N4 nanofibers were prepared by electrospinning method.•TiO2/g-C3N4 nanofibers with diameter of 100–200 nm.•The composite nanofibers displayed the best photocatalytic degradation on RhB, when the g-C3N4 content was 0.8 wt.%.•The heterojunction formed between TiO2 and g-C3N4 contributed to the improved separation of electron-hole pairs.TiO2/g-C3N4 nanofibers with diameter of 100–200 nm were prepared by electrospinning method after calcination at high temperature, using polyvinylpyrrolidone (PVP), Melamine (C3H6N6), Ti(OC4H9)4 as raw materials. The composite nanofibers were characterized by XRD, FT-IR, SEM, UV–vis and PL respectively. The effects of different g-C3N4 contents on structure and photocatalytic degradation of the composite nanofibers were investigated. The results indicated that with increasing g-C3N4 content, the diameter of the composite fibers increased and the morphology changed from uniform structure to a nonuniform one, containing beads. The composite nanofibers displayed the best photocatalytic degradation on RhB, when the g-C3N4 content was 0.8 wt%. The degree of degradation was up to 99% at the optimal conditions of 40 min. The degradation activity of the composite nanofibers on RhB, MB and MO was found to be higher than that of the TiO2 nanofibers.TiO2 can be excited by UV light and produce photogenerated electron-hole pairs. The effect of g-C3N4 and TiO2 lead to an enhanced photocatalytic activity.
Co-reporter:Hekai Zhu, Minghao Fang, Zhaohui Huang, Yangai Liu, Hao Tang, Xin Min, Xiaowen Wu
Journal of Physics and Chemistry of Solids 2016 Volume 91() pp:152-157
Publication Date(Web):April 2016
DOI:10.1016/j.jpcs.2016.01.008
•Chromium (VI) is reduced to Cr particles by aluminothermic reaction.•The conversion ratio of Na2CrO4 to metallic Cr attained 96.16%.•The Al2O3–Cr composites are used for metal-ceramics application.•This work is a potential approach to remove chromium (VI) pollutant.Reduction of chromium (VI) from Na2CrO4 through aluminothermic reaction and fabrication of metal-ceramic materials from the reduction products have been investigated in this study. Na2CrO4 could be successfully reduced into micrometer-sized Cr particles in a flowing Ar atmosphere in presence of Al powder. The conversion ratio of Na2CrO4 to metallic Cr attained 96.16% efficiency. Al2O3–Cr metal-ceramic with different Cr content (5 wt%, 10 wt%, 15 wt%, 20 wt%) were further prepared from the reduction product Al2O3–Cr composite powder, and aluminum oxide nanopowder via pressure-less sintering. The phase composition, microstructure and mechanical properties of metal-ceramic composites were characterized to ensure the potential of the Al2O3–Cr composite powder to form ceramic materials. The highest relative density and bending strength can reach 93.4% and 205 MP, respectively. The results indicated that aluminothermic reduction of chromium (VI) for metal-ceramics application is a potential approach to remove chromium (VI) pollutant from the environment.
Co-reporter:HongWei Li, Minghao Fang, Zhaohui Huang, Yan’gai Liu, Hekai Zhu, Xin Min, Lina Zhang
Chemical Physics Letters 2016 Volume 662() pp:86-90
Publication Date(Web):1 October 2016
DOI:10.1016/j.cplett.2016.09.032
•Novel BaMg2V2O8:Eu3+ phosphors are synthesized by solid-state reaction.•The luminescent properties are well characterized and studied.•The thermal stability and CIE coordinates are investigated in detail.Eu3+ doped BaMg2V2O8 (BMVO) phosphor was synthesized via a high temperature solid-state reaction method. When λex = 318 nm and Eu3+ was doped, the VO43− peak at 545 nm decreased, and a characteristic Eu3+ peak occurred together with a maximum at 620 nm. In conjunction with the decay curve, this indicates that the energy transfer from VO43− to Eu3+. Upon doping with Eu3+, the phosphor becomes color-tunable. In addition, changing the temperature between 25 and 200 °C, BMVO:0.05Eu3+ phosphor also becomes color-tunable. All results indicate that Eu3+ doped BaMg2V2O8 phosphor has many promising commercial applications.Download high-res image (116KB)Download full-size image
Co-reporter:Xiaoguang Zhang, Zhaohui Huang, Bin Ma, Ruilong Wen, Xin Min, Yaoting Huang, Zhaoyu Yin, Yangai Liu, Minghao Fang, Xiaowen Wu
Thermochimica Acta 2016 Volume 638() pp:35-43
Publication Date(Web):20 August 2016
DOI:10.1016/j.tca.2016.06.012
•WCB was a perfect carrier matrix to form-stable composite PCMs.•The preparation time of FS-CPCMs was shortened by super ultrasonic method.•Mechanism of preparing FS-CPCMs was systematically discussed.•Stability, latent heat, and thermal properties of FS-CPCMs were excellent.In this study, novel polyethylene glycol (PEG)/White Carbon Black (WCB) form-stable composite phase changes materials (FS-CPCMs) were prepared by super- ultrasound-assisted, which obviously decreases the reaction time. Test results showed that PEG does not easily leak from the fluffy network structure of WCB during solid-liquid phase transition. Results obtained from XRD and FTIR demonstrated that no new chemical bond is formed between PEG4000 and WCB. Results obtained from DSC and TGA analyses showed that FS-CPCMs exhibit excellent thermal stability and good form-stable performance. The phase change enthalpy of FS-CPCMs reached up to 101.1J/g, and the melting and solidifying times of FS-CPCMs were 34.43% and 30.51% less than that of pure PEG, respectively. The thermal conductivity data showed that WCB acted as the support material is very effective for enhancing the thermal conductivity of the FS-CPCMs. The FS-CPCMs thus prepared were safe, environmentally friendly, and cost-effective; hence, they can be used as potential building materials for the applications of thermal energy storage.The novel polyethylene glycol/White Carbon Black form-stable composite phase change materials have an optimum phase change temperature, an excellently high enthalpy of phase change, a perfect thermal stability, and the excellent heat storage/release rate.
Co-reporter:Hao Tang, Minghao Fang, Chao Tang, Zhaohui Huang, Haitao Liu, Hekai Zhu, Yangai Liu, Xiaowen Wu
Materials Science and Engineering: A 2016 Volume 655() pp:160-167
Publication Date(Web):8 February 2016
DOI:10.1016/j.msea.2015.12.097
In this study, the effect of the LaMgAl11O19 content on the mechanical properties of pressureless sintered Al2O3–LaMgAl11O19 composites, including room-temperature fracture toughness and flexural strength from room temperature to 1400 °C, was systematically investigated. Results indicated that Al2O3–LaMgAl11O19 ceramics exhibit enhanced mechanical properties as compared with those of monolithic Al2O3 ceramics both at room and elevated temperatures, with the maximum fracture toughness and flexural strength values of 4.88 MPa m1/2 and 472.8 MPa at room temperature, respectively. The flexural strength of Al2O3–LaMgAl11O19 ceramics gradually decreased with increasing test temperature below 1000 °C and sharply decreased thereafter. The improved mechanical properties of Al2O3–LaMgAl11O19 composites at ambient temperature were primarily attributed to the combination of crack deflection and bridging of LaMgAl11O19 platelets, while under elevated temperatures, the presence of LaMgAl11O19 platelets also played a crucial role in effectively hindering the grain boundaries sliding, thereby endowing superior bending strength to the composites.
Co-reporter:Zhihao Zhao, Meng Wang, Tianzi Yang, Minghao Fang, Lina Zhang, Hekai Zhu, Chao Tang, Zhaohui Huang
Journal of Molecular Catalysis A: Chemical 2016 Volume 424() pp:8-16
Publication Date(Web):1 December 2016
DOI:10.1016/j.molcata.2016.08.004
•Ag/AgBr/Bi5O7I composites were synthesized via a co-precipitation method.•The Ag/AgBr/Bi5O7I exhibited excellent photodegradation efficiencies for RhB.•Ag0 plays an important role in transformations of photogenerated electrons and holes.An Ag/AgBr/Bi5O7I heterojunction was developed using a simple in situ co-precipitation method. Ag/AgBr nanoparticles were tightly bound to Bi5O7I, improving charge transfer at the heterojunction interface. The photocatalytic activities of the Ag/AgBr/Bi5O7I composites were studied by monitoring the photodegradation of Rhodamine B (RhB) and through the generation of a transient photocurrent under visible-light irradiation (λ > 420 nm). The Ag/AgBr/Bi5O7I composites displayed enhanced photocatalytic activities compared to either pure Ag/AgBr or Bi5O7I. Charge carrier behavior was investigated using electrochemical impedance spectroscopy (EIS) which indicated the enhanced separation and transfer of photogenerated electrons and holes, thus giving to the higher photocatalytic activity. The high-performance semiconductor heterojunction developed in this work is a good candidate for photocatalytic application.A series of Ag/AgBr/Bi5O7I composites with heterostructures were synthesized via a co-precipitation method. The Ag/AgBr/Bi5O7I composites exhibited excellent photodegradation efficiencies for RhB under visible-light irradiation, which were far superior to that of Bi5O7I alone. The formation of the appropriate overlapping band energy levels is crucial for creating an effective heterojunction structure and enabling the efficient separation and transfer of photogenerated electrons and holes.
Co-reporter:Yuanjie Mao, Minghao Fang, Zhaohui Huang, Haitao Liu, Shuyue Liu, Yan-gai Liu, Xiaowen Wu, Xin Min, Chao Tang, Hao Tang and Hui Wu
RSC Advances 2015 vol. 5(Issue 77) pp:62747-62751
Publication Date(Web):15 Jul 2015
DOI:10.1039/C5RA09681B
Morphology-controlled magnesium oxide nanowhiskers have been fabricated on quartz glass fiber substrates using Mg particles as the raw material at relatively low temperatures of 550 °C and 600 °C. The as-prepared nanowhisker and nanocrosses samples were characterized using Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM), Selected Area Electron Diffraction (SAED) and Energy Dispersive X-ray Spectrum (EDS). The MgO nanowhiskers were found to have crystallized structures with growth along the [100] direction. The surfaces of the crossing whisker are considered to be in the (200) lattice plane. The partial pressure of the Mg vapor and the annealing time have played significant roles in determining the diameter and morphology of the nanowhisker. Their adsorption capacity can reduce the concentration of methylene blue solution, which may drive potential applications in biological or environmental areas.
Co-reporter:Meng Wang, Ziyu Qiao, Minghao Fang, Zhaohui Huang, Yan'gai Liu, Xiaowen Wu, Chao Tang, Hao Tang and Hekai Zhu
RSC Advances 2015 vol. 5(Issue 115) pp:94887-94894
Publication Date(Web):30 Oct 2015
DOI:10.1039/C5RA19164E
Bi2WO6:Er3+ with hierarchical flower-like microstructures were synthesized by a one-step hydrothermal method. The photocatalysts thus obtained were characterized in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectroscopy (XPS) as well as photoluminescence (PL) measurements. Results obtained by XPS confirmed the presence of Er3+ dopants in Bi2WO6. Moreover, the results obtained from SEM have shown that doping with Er ions results in hierarchical flower-like microstructures of Bi2WO6. Under visible light irradiation, with an appropriate doping content, the photocatalysts exhibit significant improvement in the photocatalytic activity as the separation efficiency of the photogenerated electron–hole pairs is enhanced. Notably, the photocatalytic activity of 1.5% Bi2WO6:Er3+ is 3.69 times that of undoped Bi2WO6. The results indicate that an appropriate doping content can improve photocatalytic activity, caused by wider band gap, hierarchical flower-like microstructures, and defects generated by doping with Er3+, which in turn increase the separation efficiency of the photogenerated electron–hole pairs.
Co-reporter:Bin Ma, Zhaohui Huang, Minghao Fang, Yangai Liu and Xiaowen Wu
RSC Advances 2015 vol. 5(Issue 13) pp:9933-9938
Publication Date(Web):06 Jan 2015
DOI:10.1039/C4RA13615B
A series of luminescent phosphate phosphors Cs1−xMgPO4:xEu2+ were synthesized via a high temperature solid-state reaction. The phase structure and photoluminescence (PL) properties, as well as the PL thermal stability of Cs0.96MgPO4:0.04Eu2+ were investigated to characterize the resulting sample. The crystal structure and chemical composition of the Cs0.96MgPO4:0.04Eu2+ phosphor were analyzed based on the Rietveld refinements and the crystal chemistry rules, respectively. The optimum concentration of Eu2+ in the CsMgPO4 phosphor was about 4 mol% and the concentration quenching effect can be attributed to the dipole–dipole interaction. This phosphor shows a broad red emission band ranging from 500 to 800 nm under the 410 nm light excitation. The above results indicate that Cs1−xMgPO4:xEu2+ phosphors have potential applications for near UV-excited w-LEDs.
Co-reporter:Hekai Zhu, Minghao Fang, Zhaohui Huang, Yan’gai Liu, Kai Chen, Chao Tang, Lina Zhang
Optical Materials 2015 Volume 49() pp:266-270
Publication Date(Web):November 2015
DOI:10.1016/j.optmat.2015.09.030
•Novel BiBa2V3O11: Sm3+/Eu3+ phosphors are synthesized by solid-state reaction.•The luminescent properties are well characterized and studied.•The thermal stability and CIE coordinates are investigated in detail.Novel rare-earth ions (Sm3+ or Eu3+) doped BiBa2V3O11 phosphors were synthesized by solid-state reaction method. BiBa2V3O11: Sm3+ phosphors emitted orange-red light under near-UV irradiation, and the strongest excitation and emission peaks were observed at 345 and 607 nm. Under the excitation of 345 nm, BiBa2V3O11: Eu3+ phosphors show the strongest emission peaks located at 622 nm corresponding to the electric dipole 5D0 → 7F2 transition. The critical quenching concentrations of Sm3+/Eu3+ in the BiBa2V3O11 lattice were 5 mol% and 8 mol%. The thermal stability of Eu3+ doped BiBa2V3O11 and CIE coordinates of BiBa2V3O11: Sm3+/Eu3+ phosphors were also investigated. The results indicate that these phosphors could be potential candidates for application in white LEDs.
Co-reporter:Zhaohui Huang, Haipeng Ji, Minghao Fang, Maxim S. Molokeev, Shuyue Liu, Yan’gai Liu, Xiaowen Wu
Chemical Physics Letters 2015 Volume 628() pp:21-24
Publication Date(Web):16 May 2015
DOI:10.1016/j.cplett.2015.04.004
•LiBaBO3:Eu2+ phosphor was successfully synthesized at T = 1023 K.•LiBaBO3:Eu2+ exhibits bright cyan emission peaking at 496 nm.•Eu2+ occupies the Ba site in LiBaBO3 forming distorted square anti-prism.•The different luminescence emission of LiBaBO3:Eu2+ and LiSrBO3:Eu2+ was explained.Cyan-emitting LiBaBO3:Eu2+ phosphor was synthesized by solid-state reaction at 800 °C. Structure refinement by Rietveld method reveals that LiBaBO3 crystallizes in a monoclinic cell, space groups P21/c or P21/n. Upon 365 nm excitation, LiBaBO3:Eu2+ shows a symmetric emission band peaking at 496 nm with full-width at half-maximum of 80 nm; when monitoring at 496 nm, a broad excitation band in the UV region (250–420 nm) is observed. The luminescence property of LiBaBO3:Eu2+ is considerably different from LiSrBO3:Eu2+ which holds the same space group. The local structures of the two hosts are compared to explain the different behaviors of Eu2+.
Co-reporter:Xin Min, Minghao Fang, Zhaohui Huang, Hao Liu, Yan’gai Liu, Chao Tang, Xiaowen Wu
Chemical Physics Letters 2015 Volume 618() pp:182-185
Publication Date(Web):2 January 2015
DOI:10.1016/j.cplett.2014.11.011
•LaMgAl11O19:Ho3+ phosphors were successfully synthesized at 1600 °C for 4 h.•LaMgAl11O19:Ho3+ phosphors emitted green light exciting by n-UV or blue light.•LaMgAl11O19:Ho3+ phosphors exhibited an excellent thermal stability.•LaMgAl11O19:Ho3+ is a promising green phosphor for tricolor w-LEDs.A novel green phosphor LaMgAl11O19:Ho3+ was synthesized by a solid-state reaction method. The LaMgAl11O19:Ho3+ phosphor showed a strong green emission peak centered at 550 nm and a weak red emission peak at 658 nm, when excited at 452 nm. The electric dipole–dipole interaction resulted in the concentration quenching, when the Ho3+ doping concentration was 0.1 mol. The emission intensity at 150 °C was shown to be 91.6% of that at room temperature, which verifies a good thermal stability for LaMgAl11O19:Ho3+ phosphors. The results indicated that LaMgAl11O19:Ho3+ material is a promising green phosphor for the application as near-UV/blue light-pumped w-LEDs.
Co-reporter:Haitao Liu, Zhaohui Huang, Juntong Huang, Minghao Fang, Yan-gai Liu and Xiaowen Wu
Journal of Materials Chemistry A 2014 vol. 2(Issue 37) pp:7761-7767
Publication Date(Web):25 Jul 2014
DOI:10.1039/C4TC01391C
Core–shell SiC/SiOx nanochain heterojunctions have been successfully synthesized on silicon substrate via a simplified thermal evaporation method at 1500 °C without using catalyst, template or flowing gases (Ar, CH4, N2, etc.). X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy combined with energy-dispersive X-ray spectroscopy, scanning transmission electron microscopy and Fourier-transform infrared spectroscopy are used to characterize the phase composition, morphology, and microstructure of the as-synthesized nanostructures. A combined vapor–solid growth and modulation procedure is proposed for the growth mode of the as-grown SiC/SiOx nanochains. The formation of SiOx beads not only relates to the Rayleigh instability and the poor wettability between SiC and SiOx, but also to the existence of a high density of stacking faults within SiC-core nanowires. The photoluminescence spectrum of the nanochains exhibits a significant blue shift, which can be highly valuable for future potential applications in blue-green emitting devices.
Co-reporter:Xin Min, Zhaohui Huang, Minghao Fang, Yan-Gai Liu, Chao Tang, and Xiaowen Wu
Inorganic Chemistry 2014 Volume 53(Issue 12) pp:6060-6065
Publication Date(Web):June 2, 2014
DOI:10.1021/ic500412r
The red-emitting phosphor LaMgAl11O19:Sm3+, Eu3+ was prepared by solid-state reaction at 1600 °C for 4 h. The phase formation, luminescence properties, and energy transfer from Sm3+ to Eu3+ were studied. With the addition of 5 mol % Sm3+ as the sensitizer, the excitation wavelength of LaMgAl11O19:Eu3+ phosphor was extended from 464 to 403 nm, and the emission intensity under the excitation at 403 nm was also enhanced. The host material LaMgAl11O19 could contain the high doping content of Eu3+ (20 mol %) without concentration quenching. This energy transfer from Sm3+ to Eu3+ was confirmed by the decay times of energy donor Sm3+. The mechanism of energy transfer (Sm3+ → Eu3+) was proved to be quadrupole–quadrupole interaction. Under the 403 nm excitation at 150 °C, the emission intensities of the characteristic peaks of Sm3+ and Eu3+ in LaMgAl11O19:0.05Sm3+, 0.2Eu3+ phosphor were decreased to 65% and 56% of the initial intensities at room temperature, and the relatively high activation energy proved that this phosphor had a good thermal stability. The CIE coordinate was calculated to be (x = 0.601, y = 0.390). The LaMgAl11O19:0.05Sm3+, 0.2Eu3+ phosphor is a candidate for copper phthalocyanine-based solar cells and white light-emitting diodes.
Co-reporter:Gansheng Yang, Li Yin, Xian-ge Fang, Minghao Fang, Yan-gai Liu, Zhaohui Huang, Baolin Liu
Ceramics International 2014 Volume 40(Issue 7) pp:10737-10741
Publication Date(Web):August 2014
DOI:10.1016/j.ceramint.2014.03.061
Abstract
In this paper, β-Sialon ceramic was formed with pyrophyllite as raw material and coke as reductant by carbothermal reduction and nitridation in flowing nitrogen atmosphere. Then, the erosion wear property of β-Sialon ceramic was measured. When the pre-synthesized temperature was 1400 °C, the effects of carbon additions (with theoretical carbon addition and carbon in excess of 10–50 wt.%) on the phase compositions of the products were studied by X-ray diffraction. β-Sialon ceramic was sintered at 1600 °C, and its erosion wear behavior was examined with the use of a self-designed, liquid–solid, two-phase flow erosion equipment. Results show that the optimum carbon addition to fabricate the β-Sialon ceramic powders was in excess of 10 wt% at 1400 °C. Under these conditions, the pre-synthesized powders were composed of β-Sialon as the main crystalline phase and β-SiC as the secondary phase. The relationship between volume erosion amount per area of the specimens and erosion time can be explained by two exponential equations—ΔV=−5.2t2+10.4t and ΔV=−0.006t2+0.273t+4.884 in two stages.
Co-reporter:Zhaohui Huang, Haitao Liu, Kai Chen, Minghao Fang, Juntong Huang, Shuyue Liu, Saifang Huang, Yan-gai Liu and Xiaowen Wu
RSC Advances 2014 vol. 4(Issue 35) pp:18360-18364
Publication Date(Web):07 Apr 2014
DOI:10.1039/C4RA00073K
Twinned SiC nanowires were prepared on a silicon wafer by a catalyst-free thermal chemical vapour deposition (CVD) method at 1500 °C in a flowing Ar atmosphere. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM) were used to characterise the phase composition, morphology, and microstructure of the as-received nanowires. The as-synthesised twinned nanowires were up to several hundred microns long and had relatively homogeneous diameters in the range 20 to 100 nm. The growth process of the twinned SiC nanowires was dominated by a vapour–solid (VS) mechanism. Based on the competition of stacking fault energy and electrostatic energy, a growth model has been proposed to understand the phenomenon of twinning.
Co-reporter:Xin Min, Minghao Fang, Zhaohui Huang, Yan’gai Liu, Chao Tang, Hekai Zhu, Xiaowen Wu
Optical Materials 2014 Volume 37() pp:110-114
Publication Date(Web):November 2014
DOI:10.1016/j.optmat.2014.05.008
•LaMgAl11O19:Sm3+ phosphors were synthesized at 1600 °C for 4 h.•The phosphors present an orange reddish emission under 403 nm excitation.•The d–d interactions result in the concentration quenching with 5 mol% Sm3+ added.•The LaMgAl11O19:Sm3+ phosphor presents a potential application in w-LEDs.An orange reddish emitting phosphor, LaMgAl11O19:Sm3+, was synthesized by a high temperature solid-state reaction, and the phase formation, crystal structure and luminescence properties were investigated respectively. The LaMgAl11O19:Sm3+ phosphor presents a highly intense orange reddish emission peak under the near ultraviolet excitation at 403 nm, which is corresponds to the 4G5/2 → 6HJ (J = 5/2, 7/2, 9/2 and 11/2) transitions of Sm3+ ions. It was found that the dipole–dipole interactions mainly results in the concentration quenching in the LaMgAl11O19:Sm3+ phosphor with a critical quenching concentration at about 5 mol%. The temperature dependence of luminescence properties was studied from 25 to 200 °C and indicated that LaMgAl11O19:0.05Sm3+ phosphors had a relatively higher quenching temperature. The chromatic properties of LaMgAl11O19:0.05Sm3+ phosphor have been found to have chromaticity coordinate of (0.578, 0.420). All these properties indicate that the orange reddish emitting LaMgAl11O19:Sm3+ phosphor has a potential application in w-LEDs.
Co-reporter:Xin Min, Minghao Fang, Zhaohui Huang, Yangai Liu, Chao Tang, Xiaowen Wu
Materials Letters 2014 Volume 125() pp:140-142
Publication Date(Web):15 June 2014
DOI:10.1016/j.matlet.2014.03.171
•The CIE coordinate LaMgAl11O19:Dy3+ phosphor is close to the white light coordinate.•LaMgAl11O19:Dy3+ phosphor hasa good thermal stability.•LaMgAl11O19:Dy3+ is proved to be a promising single-phase phosphor for w-LEDs.The LaMgAl11O19:Dy3+ phosphors were prepared by the high-temperature solid-state reaction method. The phase structure, luminescence properties, and the thermal stability of the phosphors were investigated. Under the excitation of 349 nm, the LaMgAl11O19:Dy3+ phosphors exhibited three emission peaks at 475 nm, 570 nm, and 664 nm, which respectively corresponded to the 4F9/2→6H15/2, 4F9/2→6H15/2, and 4F9/2→6H11/2 transitions. It was proved that dipole–dipole interaction resulted in the concentration quenching with a quenching concentration of 0.1 mol. The emission intensity at 150 °C was stronger than that at 25 °C, indicating the good thermal stability of LaMgAl11O19:Dy3+ phosphors. The CIE coordinates of LaMgAl11O19:Dy3+ phosphors are very close to the white light coordinates (x=0.3333 and y=0.3333). Therefore, LaMgAl11O19:Dy3+ phosphor is a promising single-phase phosphor for white light emitting diodes.
Co-reporter:Xiaojun Wang, Minghao Fang, Lai-Chang Zhang, Hao Ding, Yan-Gai Liu, Zhaohui Huang, Shaoping Huang, Jingzhou Yang
Materials Chemistry and Physics 2013 Volume 139(2–3) pp:765-769
Publication Date(Web):15 May 2013
DOI:10.1016/j.matchemphys.2013.02.029
A big gap exists for the understanding of the influence of temperature on erosion behavior at elevated temperature between experimental observations (up to 1100 °C) and high temperature industrial application (up to 1600 °C). This work the first time investigated the effect of higher temperature on the erosion resistance and mechanism of alumina ceramics. The solid particle erosion behavior of high purity alumina ceramics has been studied at elevated temperatures up to 1400 °C and different impingement angles (30°, 45°, 60°, 75°, and 90°), using corundum and SiC particles as erodent. Erosion rate of alumina ceramics slowly increases from 0.32 mm3 g−1 to 0.44 mm3 g−1 below 800 °C, and then significantly increases up to 1.30 mm3 g−1 at 1400 °C. With increasing the impingement angle, the erosion rate increases slightly and reaches maximum value at 90° from room temperature to 800 °C. However, the maximum value of erosion rate occurs at 75° and 60° for 1200 °C and 1400 °C, respectively. The brittle erosion mechanisms still dominate the material removal at elevated temperature. The material removal is mainly resulted from transgranular cleavage and grain removal.Graphical abstractVariation of erosion rate as a function of the impingement angle with different temperatures.Highlights► The erosion rate of alumina ceramics increases slowly from room temperature to 800 °C, then sharply rising above 800 °C. ► The maximum erosion rate took place at 75° and 60° for 1200 °C and 1400 °C. ► There is no obviously evidence of plastic deformation at 1200 °C and 1400 °C. ► The harder SiC particles lead to more severe erosion damage of alumina ceramics, compared with corundum grits.
Co-reporter:MeiLing Hu;Chao Tang;Tao Yang;ZhaoHui Huang
Nanoscale Research Letters 2013 Volume 8( Issue 1) pp:
Publication Date(Web):2013 December
DOI:10.1186/1556-276X-8-548
TiO2-based nanofibers were synthesized using a sol–gel method and electrospinning technique. The as-spun composite fibers were heat-treated at different temperatures (500°C, 550°C, 600°C, and 650°C) and atmospheres (ammonia and nitrogen) for 4 h. The fibers had diameters of 50 to 200 nm and mainly featured anatase and rutile phases. The anatase phase decreased and the rutile phase increased with increasing temperature. Different nitrogen conditions exerted minimal effects on the TiO2 crystalline phase. Different nitriding atmospheres during preservation heating yielded various effects on fibers. The effect of nitrogen in ammonia atmosphere is better than that in nitrogen atmosphere. The fibers heat-treated at 600°C and subjected to preservation heating in NH3 showed high photocatalytic activity.
Co-reporter:Yan-Gai Liu;Peng Peng;Zhaohui Huang
Advanced Engineering Materials 2012 Volume 14( Issue 3) pp:170-177
Publication Date(Web):
DOI:10.1002/adem.201100122
Abstract
Rare-earth aluminate ceramics for thermal-barrier coatings (TBCs) are synthesized. The Young's modulus and thermal properties decrease with erbium additive increasing. The Y3−xErxAl5O12 ceramics (x = 1, 3) possess a much-lower thermal conductivity compared with 8YSZ. The lower Young's modulus and thermal-expansion coefficient are due to the larger atomic weight of the Er substitutional atom. Additional phonon-scattering effects also contribute to the lower thermal conductivity. The results indicate that Y3−xErxAl5O12 can be explored as a candidate material for TBC systems. A theoretical model that describes the influence of point defects on the thermal conductivity is discussed.
Co-reporter:Feng-Jiao Liu, Ming-Hao Fang, Zhao-Hui Huang, Yan-Gai Liu, Sai-Fang Huang, Xin Min, Mei-Ling Hu, Hai-Peng Ji
Materials Science and Engineering: A 2012 Volume 554() pp:1-5
Publication Date(Web):30 September 2012
DOI:10.1016/j.msea.2012.05.004
The mechanical properties of the 8 mol% yttria stabilized zirconia (8YSZ), as a promising anodic material for solid oxide fuel cell, should be improved to increase its reliability and service life. NiCr–Al2O3–ZrO2(8Y) ceramic composites were successfully fabricated by pressureless sintering in the carbothermal protecting atmosphere, and the mechanical properties and microstructure were investigated as well. The results showed that 8YSZ matrix composites had good mechanical properties due to the NiCr alloy and α-Al2O3 secondary phases. The bending strength and fracture toughness could reach at a range of 224–300 MPa, 3.8–4.6 MPa m1/2, respectively, when 0–12 vol.% of NiCr alloy and 10 vol.% alumina particles were added into 8YSZ ceramic. 10 vol.% α-Al2O3 obviously enhanced the densification of the 8YSZ ceramic.Highlights► Pressureless sintering method and carbothermal protecting atmosphere were adopted. ► Adding 0–12 vol.% NiCr alloy and 10 vol.% alumina can boost properties of 8YSZ ceramic. ► Fracture toughness of 8YSZ-based composite reached a maximum value of 4.6 MPa m1/2. ► NiCr alloy and α-Al2O3 located at the ZrO2 grain boundaries or triple junctions.
Co-reporter:B. Jiang, M.H. Fang, Z.H. Huang, Y.G. Liu, P. Peng, J. Zhang
Materials Research Bulletin 2010 45(10) pp: 1506-1508
Publication Date(Web):
DOI:10.1016/j.materresbull.2010.06.014
Co-reporter:Haipeng Ji, Minghao Fang, Zhaohui Huang, Kai Chen, Wenjuan Li, Yan-gai Liu
Applied Clay Science (November 2014) Volume 101() pp:94-99
Publication Date(Web):November 2014
DOI:10.1016/j.clay.2014.07.023
Co-reporter:Wen-Juan Li, Zhao-Hui Huang, Yan-Gai Liu, Ming-Hao Fang, Xin Ouyang, Sai-Fang Huang
Applied Clay Science (March 2012) Volume 57() pp:86-90
Publication Date(Web):March 2012
DOI:10.1016/j.clay.2012.01.006
Co-reporter:Ruilong Wen, Zhaohui Huang, Yaoting Huang, Xiaoguang Zhang, Xin Min, Minghao Fang, Yan’gai Liu, Xiaowen Wu
Energy and Buildings (15 March 2016) Volume 116() pp:677-683
Publication Date(Web):15 March 2016
DOI:10.1016/j.enbuild.2016.01.023
Lauric acid(LA)/expanded vermiculite (EVM) form-stable phase change materials were synthesized via vacuum impregnation method. In the composites, lauric acid was utilized as a thermal energy storage material and the expanded vermiculite behaved as the supporting material. XRD and FT-IR results demonstrate that lauric acid and expanded vermiculite in the composite do not undergo a chemical reaction and only undergo a physical combination. Microstructural analysis indicates that lauric acid is sufficiently absorbed in the expanded vermiculite porous network, while displaying negligible leakage even under the molten state. According to DSC results, the 70 wt.% LA/EVM sample melts at 41.88 °C with a latent heat of 126.8 J/g and solidifies at 39.89 °C with a latent heat of 125.6 J/g. Thermal cycling measurements show that the form-stable composite PCM has adequate stability even after being subjected to 200 melting/freezing cycles. Furthermore, the thermal conductivity of the composite PCM increased by approximately 78% with the addition of 10 wt.% expanded graphite (EG). Thus, the form-stable composite PCM is a suitable option for thermal energy storage for building and solar heating system applications.
Co-reporter:Haitao Liu, Zhaohui Huang, Juntong Huang, Minghao Fang, Yan-gai Liu and Xiaowen Wu
Journal of Materials Chemistry A 2014 - vol. 2(Issue 37) pp:NaN7767-7767
Publication Date(Web):2014/07/25
DOI:10.1039/C4TC01391C
Core–shell SiC/SiOx nanochain heterojunctions have been successfully synthesized on silicon substrate via a simplified thermal evaporation method at 1500 °C without using catalyst, template or flowing gases (Ar, CH4, N2, etc.). X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy combined with energy-dispersive X-ray spectroscopy, scanning transmission electron microscopy and Fourier-transform infrared spectroscopy are used to characterize the phase composition, morphology, and microstructure of the as-synthesized nanostructures. A combined vapor–solid growth and modulation procedure is proposed for the growth mode of the as-grown SiC/SiOx nanochains. The formation of SiOx beads not only relates to the Rayleigh instability and the poor wettability between SiC and SiOx, but also to the existence of a high density of stacking faults within SiC-core nanowires. The photoluminescence spectrum of the nanochains exhibits a significant blue shift, which can be highly valuable for future potential applications in blue-green emitting devices.
