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Effect of NaCl on synthesis of ZrB2 by a borothermal reduction reaction of ZrO2 被引量:2
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作者 Yu Wang Yue-dong Wu +3 位作者 Ke-han Wu Shu-qiang Jiao Kuo-chih Chou Guo-hua Zhang 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2019年第7期831-838,共8页
ZrB2 powders were synthesized via a borothermal reduction reaction of ZrO2 with the assistance of NaCl under a flowing Ar atmosphere. The optimal temperature and reaction time were 1223 K and 3 h, respectively. Compar... ZrB2 powders were synthesized via a borothermal reduction reaction of ZrO2 with the assistance of NaCl under a flowing Ar atmosphere. The optimal temperature and reaction time were 1223 K and 3 h, respectively. Compared with the reactions conducted without the addition of NaCl, those performed with the addition of an appropriate amount of NaCl finished at substantially lower temperatures. However, the addition of too much NaCl suppressed this effect. With the assistance of NaCl, a special morphology of polyhedral ZrB2 particles covered with ZrB2 nanosheets was obtained. Moreover, the experimental results revealed that the special morphology was the result of the combined effects of B2O3 and NaCl. The formation of the special microstructure is explained on the basis of the “dissolution–recrystallization” mechanism. 展开更多
关键词 ZIRCONIUM DIBORIDE borothermal reduction ultra-high temperature ceramics dissolution-recrystallization mechanism
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Bright and tunable emissive monodisperse CsPbI3@Cs4PbI6 nanocomposites via a precise and controllable dissolution−recrystallization method 被引量:2
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作者 Luyu Cao Bomei Liu +4 位作者 Lin Huang Zhi Zhou Chong-Geng Ma Jian Zhang Jing Wang 《Nano Research》 SCIE EI CSCD 2023年第1期1586-1594,共9页
Nowadays,due to uncontrolled synthesis and lack of more direct and systematic evidences,the photoluminescence origin of“zero-dimensional”Cs4PbI6 remains great controversy and the luminescence cannot be controlled.He... Nowadays,due to uncontrolled synthesis and lack of more direct and systematic evidences,the photoluminescence origin of“zero-dimensional”Cs4PbI6 remains great controversy and the luminescence cannot be controlled.Here we propose a controllable dissolution-recrystallization method to synthesize“emissive”and“non-emissive”Cs4PbI6 nanocrystals(NCs)respectively.Through comparing“emissive”and“non-emissive”Cs4PbI6 NCs,it is clearly proved that the visible emission in“emissive”Cs4PbI6 NCs comes from embedded CsPbI3 quantum dots(QDs).It is found for CsPbI3@Cs4PbI6 nanocomposites,methyl acetate(MeAC)and cyclohexane play an important role in dissolution and recrystallization respectively to obtain Cs4PbI6 matrix and CsPbI3 cores.Benefiting from this two-step method,the as-synthesized CsPbI3@Cs4PbI6 nanocomposites with CsPbI3 QDs uniformly distributed in Cs4PbI6 matrix are bright with photoluminescence quantum yield(PLQY)up to 71.4%and exhibit improved stability than CsPbI3 NCs.Moreover,utilizing its formation mechanism,the size of embedded CsPbI3 QDs can be controlled by reasonable designing the“dissolution”process,so that the luminescence of this CsPbI3@Cs4PbI6 nanocomposites can be adjusted in a wide range from green to red(554–630 nm).Our finding not only provides a novel method for synthesizing tunable“emissive”Cs4PbI6 NCs,but also makes clear the photoluminescence origin of“emissive”Cs4PbI6. 展开更多
关键词 CsPbI3@Cs4PbI6 dissolution-recrystallization NANOCOMPOSITES tunable emission
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Characterization and precipitation mechanism of α-calcium sulfate hemihydrate growing out of FGD gypsum in salt solution 被引量:14
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作者 YANG LiuChun GUAN BaoHong WU ZhongBiao 《Science China(Technological Sciences)》 SCIE EI CAS 2009年第9期2688-2694,共7页
Alpha-calcium sulfate hemihydrate (α-HH) has been prepared from flue gas desulfurization (FGD) gypsum with salt solution method under atmospheric pressure. X-ray diffraction (XRD),thermogra-vimetry and differential s... Alpha-calcium sulfate hemihydrate (α-HH) has been prepared from flue gas desulfurization (FGD) gypsum with salt solution method under atmospheric pressure. X-ray diffraction (XRD),thermogra-vimetry and differential scanning calorimetry (TG-DSC),optical micrograph,X-ray photoelectron spec-troscopy (XPS),energy dispersive spectrometry (EDS),and scanning electron microscopy (SEM) have been employed to characterize the α-HH crystals,based on which the formation and growth mecha-nisms of the α-HH crystals have been discussed. The results show that FGD gypsum can be success-fully transformed into high purity α-HH in salt solution under mild conditions,and that a dissolu-tion-recrystallization route is most probably adopted by this transition. The growth of α-HH crystals in salt solution demonstrates a preferred direction along [001] and results in a bundle-of-sheets or bun-dle-of-raphide texture. The characteristics revealed in this study can help to understand and control the growth of the α-HH crystal from solution. 展开更多
关键词 FGD GYPSUM calcium SULFATE HEMIHYDRATE dissolution-recrystallization salt solution method
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Single-crystal microplates of two-dimensional organic-inorganic lead halide layered perovskites for optoelectronics 被引量:3
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作者 Dewei Ma Yongping Fu +3 位作者 Lianna Dang Jianyuan Zhai Ilia A. Guzei Song Jin 《Nano Research》 SCIE EI CAS CSCD 2017年第6期2117-2129,共13页
Organic-inorganic hybrid perovskites attract considerable attention owing to their applications in high-efficiency solar cells and light emission. Compared with three-dimensional perovskites, two-dimensional (2D) la... Organic-inorganic hybrid perovskites attract considerable attention owing to their applications in high-efficiency solar cells and light emission. Compared with three-dimensional perovskites, two-dimensional (2D) layered hybrid perovskites have a higher exciton binding energy and potentially higher light- emission efficiency. The growth of high-quality crystalline 2D perovskites with a well-defined nanoscale morphology is desirable because they can be suitable building blocks for integrated optoelectronics and (nano)photonics. Herein, we report the facile solution growth of single-crystal microplates of 2D perovskites based on a 2-phenylethylammonium (C6HsCH2CH2NHG PEA) cation, (PEA)2PbX- (X = Br, I), with a well-defined rectangular geometry and nanoscale thickness through a dissolution-recrystallization process. The crystal structures of (PEA)2PbX4 are first confirmed using single-crystal X-ray diffraction. A solution-phase transport-growth process is developed to grow microplates with a typical size of tens of micrometers and thickness of hundreds of nanometers on another clean substrate different from the substrate coated with lead-acetate precursor film. Surface-topography analysis suggests that the formation of the 2D microplates is likely driven by the wedding-cake growth mechanism. Through halide alloying, the photoluminescence emission of (PEA)2Pb(Br, I)4 perovskites with a narrow peak bandwidth is readily tuned from violet (-410 nm) to green (-530 nm). 展开更多
关键词 layered lead-halide perovskite phenylethylammonium lead-halide perovskites microplate nanoplate dissolution-recrystallization photoluminescence
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