Crystals
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2022
·Vol. 12
·期 11
·1608
·
IF 2.67
Zijun Ye,Yu Jiang,Minmin Mao,Zhiyu Xiu,Mengjiao Chi,Guofa Wu,Bing Liu,Dawei Wang,Bin Yang,Kaixin Song
In this work, Y2.95R0.05MgAl3SiO12(R = Yb, Y, Dy, Eu, Sm) microwave single-phase dielectric ceramics were successfully prepared via a conventional ceramic sintering technology by doping a series of rare earth elements (Yb, Y, Dy, Eu, Sm) with different ionic radii for the first time. The effects of A-sites occupied by rare earth elements on the microwave dielectric properties of Y2.95R0.05MgAl3SiO12were studied using crystal structure refinement, a scanning electron microscope (SEM), bond valence theory, P-V-L theory, and infrared reflection spectroscopy. It was found that the ionicity of the Y-O bond, the lattice energy, the bond energy, and the bond valance of the Al(Tet)-O bond had important effects on the microwave dielectric properties. Particularly, the optimum microwave dielectric properties,εr= 9.68,Q×f= 68,866 GHz, andτf= −35.8 ppm/°C, were obtained for Y2.95Dy0.05MgAl3SiO12when sintered at 1575 °C for 6 h, displaying its potential for 5G communication.Keywords:garnet;microwave dielectric properties;P–V–L theory;infrared reflection spectroscopy
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APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING
·
2022
·Vol. 128
·期 12
·1-18
·
IF 2.983
He Yuan,Guo Shenghui,Li Shiwei,Yin Shaohua
Y Zeolite plays an irreplaceable role in many important applications due to its unique physicochemical properties, which has attracted extensive attention from researchers. Response surface methodology (RSM) was used to optimize the process parameters for the hydrothermal synthesis of Y zeolite using kaolin activated by microwave heating. The best relative crystallinity was 108.17% could be achieved at the condition: the aging temperature of guiding agent was 65 ℃, the crystallization temperature was 100 ℃, the crystallization time was 24 h. In addition, the aging temperature of guiding agent was the most important influence factor. Under the optimal condition, the SiO 2 /Al 2 O 3 ratio of synthesized Y zeolite was 4.54, 90% of the particle size was less than 60 μm, and the specific surface area of Y zeolite was 479 m 2 /g. The successful preparation of Y zeolite with high crystallinity is expected to provide reference for the application of wastewater treatment, CO 2 sequestration and fluid catalytic cracking for petroleum.
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JOURNAL OF RARE EARTHS
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2022
·
IF 4.632
Yuxing Bai,Liwei Wu,Qilin Cheng,Li Wu,Yongfa Kong,Yi Zhang,Jingjun Xu
Thermal stability is a crucial index to assess application value of high-power LEDs, which is related to lattice defects. Herein, an effective structure - engineering strategy is proposed to achieve excellent properties. Under the 394 nm excitation, Cs 3 Zn 5.94 B 9 O 21 :0.06Eu 3+ possesses two characteristic emissions peaked at 591 and 612 nm with limited thermal stability. By introducing Li + ions into the lattice, the sample exhibits high color purity and excellent zero-thermal quenching because the defect contents of the phosphor can be effectively modulated via charge-compensation effect. Then, under the stimulus of high temperature, the corresponding trap levels with a suitable depth ( E = 1.27 eV) will release electrons to recombine with the luminescent centers, compensating for the energy loss. The study provides a meaningful guide for optimizing and designing novel functional photoluminescent materials.
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ACS Applied Nano Materials
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2021
·
IF 5.097
Jianzhong Yu,Song Ye,Huazhen Liao,Xinling Xv,Deping Wang
Silver nanoclusters (Ag NCs) are emissive centers that are characteristic of high quantum yield, tunable emission, and large Stokes shift when confined inside zeolites, and their luminescence property is closely related to the cluster size, charge state, local environment, and extra activation. In this research, we evaluated the luminescence response of Ag NCs on the extra-framework cations by considering Na-type FAU-Y (NaY) as the parent zeolite. The extra-framework cations Na+ were partially substituted with Li+ or Ca2+ through the ion-exchange method and analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FT-IR) measurements, based on which a series of MYAg (M = Na, Li, Ca) zeolites were prepared through subsequent Ag+ exchange and thermal treatment under 600 °C for 2 h. The influence of extra-framework cations on the lattice parameter of the host zeolite, the exchange efficiency of Ag+, the formation ability, and the chemical state and luminescence property of Ag NCs was studied through the combination of structural and spectral measurements. This research indicated a flexible pathway for manipulating the luminescence property of Ag NCs, and the extra-framework cation-dependent luminescence property enables the FAU-Y zeolite to become a desirable host for the stabilization of Ag NCs to achieve highly efficient tunable emission.
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CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Haowei Liu,Tao Zheng,Tianli Hui,Rui Zhang,Xianghai Meng,Wenshuai Zhu,Haiyan Liu,Zhichang Liu
Conversion of ethanol to high-value alcohols is an attractive approach for developing renewable biofuels, the key is to develop stable and high-efficient catalysts. In this work, based on the preparation strategy of heteroatomic Beta zeolites, a bifunctional Pt-Y/Beta catalyst was prepared by solid-state ion exchange and impregnation. Through characterization techniques such as TEM, NMR and XAS, it was confirmed that the Y species were incorporated into the framework of Beta zeolite by interacting with the silanol groups located at the defect sites, while the Pt species were confirmed to be present on the surface of the zeolite in the form of dispersed nanoparticles . The unique structure form and the favorable spatial proximity of the two metallic active sites lead to a synergistic catalysis, which enable a one-step conversion of ethanol to n-butanol with exceptionally high selectivity of 68 %. In situ DRIFT characterization, ethanol-TPD and relay experiment results show that in the ethanol to n-butanol reaction, the Pt species in Pt-Y/Beta catalyst serves as the active center for the dehydrogenation of ethanol and the hydrogenation of crotonaldehyde and crotyl alcohol, while the Y species is responsible for catalyzing the condensation reaction of acetaldehyde.
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MICROPOROUS AND MESOPOROUS MATERIALS
·
2021
·
IF 5.455
Bo Meng,Shenyong Ren,Zhi Li,Suofu Nie,Xinyue Zhang,Weiyu Song,Qiaoxia Guo,Baojian Shen
The direct synthesis of zeolite Y with high SiO 2 /Al 2 O 3 (SAR > 6.0) and small crystal size is a great challenge. The conventional production of high silica Y usually involves organic template into the synthesis system, which takes high cost. Here, zeolite Y with SAR of 6.15 and small crystal size via introducing Co 2+ in a facile one-step hydrothermal method without organic template was achieved. The SAR increased from 5.2 to 6.15 compared to normal NaY, and the crystal size decreased to 50%. The introduction of Co 2+ in synthesis system affects the formation of 5-coordination intermediate ( M-O -Si )* around Co 2+ during crystallization process which is the critical factor to nucleation. The stability of ( Co–O –Si )* is weaker than that of ( Al–O –Si )*, which leads to the increase of SAR around Co 2+ . The microcrystals of Co(OH) 2 provide adhesive surface for the amorphous material and promote nucleation. The zeolite Y shows good performance in the cracking of 1,3,5-triisopropylbenzene because of larger surface area and more active sites being exposed. This is a new strategy for industrial synthesis of high SiO 2 /Al 2 O 3 and small crystal size zeolite Y.
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ADVANCED POWDER TECHNOLOGY
·
2019
·
IF 3.25
Zepeng Lv,Dong Liu,Yijie Wu,Run Zhang,Haibo Sun,Jie Dang,Liwen Hu
Tungsten, one of the refractory metals, has lots of excellent properties, making tungsten powders become a choice of raw material for many applications. This work reported a simple method (the salt-assisted hydrogen reduction of WO 3 powders) for preparing tungsten powders with desired morphologies and size. By adjusting the amount of additive (Y(NO 3 ) 3 ) and reduction temperature, metallic tungsten particles with different morphologies and size were obtained. It was found that both temperature and additive had apparent effects on the morphology and size of metallic W particles, and the large parallelepiped-shaped powders disappeared and large irregular blocky-shaped powders were degraded under the influence of additive. With the increase of temperature and amount of salt, particles became more dispersed and the size increased at higher temperatures, and the shape of particles was changed from spherical to polyhedral as well. On the contrary, the size of sub-particles became smaller as increasing amount of Y(NO 3 ) 3 at lower temperatures. Based on the results, the reaction and refining mechanisms for preparing tungsten were proposed as well.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2019
·
IF 4.175
Lin He,Yimin Gao,Yefei Li,Zhiwei Liu,Weiyao Zhang,Guangcan Zhou,Hongying He,Siyong Zhao,Honggang Liu,Wentao Yan
Ti(C,N)-304ss cermets with various rare earth yttrium addition were fabricated via powder metallurgy . Fe and Cr atoms dissolved into Ti(C,N) grains and formed a core-rim structure. The first-principle method was employed to calculate the lattice parameters and elastic modulus of the solid solution. The formation of solid solution not only reduced the lattice misfit between the binder phase and hard phase but also improved the hardness of hard phase. The in-situ formed nano-Y 2 O 3 particles existed at the center of Ti(C,N) grains acting as ‘mid effect’ heteromorphic nuclei. The microstructure of cermets was refined with Y addition and the abnormal growth of hard phase was suppressed. The mechanical properties were also improved with Y addition. When the Y content reached 0.3 wt%, the optimal mechanical properties were obtained with a TRS value of 1527 MPa and a hardness value of 91.7 HRA.
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POLYMER BULLETIN
·
2019
·Vol. 77
·期 2
·1049-1066
·
IF 1.858
Zhang Mengmeng,Yu Zehao,Yu Hongchao
Ferroferric oxide/polypyrrole (Fe 3 O 4 /PPy) composites were prepared by an in situ polymerization method. Several analysis techniques including X-ray diffraction, Fourier transform infrared spectra, thermogravimetric analysis and scanning electron microscopy are applied to analyze the structure and morphology of Fe 3 O 4 /PPy. The magnetic Fe 3 O 4 /PPy was further used as an adsorbent for removing Eosin Y, methyl orange and brilliant green from aqueous phase. The adsorption kinetics were investigated by pseudo-first-order, pseudo-second-order and intraparticle diffusion models, and the experimental data were well fitted to the pseudo-second order. The equilibrium adsorption data can be described by both the Langmuir and Freundlich isotherm models. The calculated Langmuir maximum adsorption capacities of Eosin Y, methyl orange and brilliant green at 25 °C are 212.31, 149.48 and 263.85 mg/g, respectively. Thermodynamic studies indicated that the adsorption process occurred spontaneously, in an endothermic and physisorption nature, and with increased disorder. Furthermore, the convenient magnetic separability of Fe 3 O 4 /PPy makes it a good candidate for practical application in the removal of organic dyes from polluted water.
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MICROCHEMICAL JOURNAL
·
2018
·
IF 2.746
Lili Yu,Hui Xu,Hou Chen,Shengxiao Zhang,Tingting Jiang,Liangjiu Bai,Wenxiang Wang,Shanmin Gao,Juan Jin
A label-free DNA Y junction sensor for amplified detection of Hg 2+ has been demonstrated by using thymine-Hg 2+ -thymine (T-Hg 2+ -T) recognition, cascade toehold-mediated DNA strand displacement and dye staining double-stranded DNA (dsDNA). In our work, assistant DNA could bind with the first hairpin DNA with toehold domains by the help of thymine-Hg 2+ -thymine (T–Hg 2+ –T) base pairs recognition. The second hairpin DNA with toehold domains will then hybridize with the complementary sequences in first hairpin DNA, which again initiates a new toehold domains to open the third hairpin DNA, triggering a cascade strand displacement reaction. Exonuclease III (Exo III) was added to digest the three hairpin DNA with recessed 3′ ends in the absence of Hg 2+ to reduce the background signal. As a comparison, Exo III is replaced by GO to reduce the background signal because single-strand DNA (ssDNA), three hairpin DNAs with intercalated dye could be adsorbed onto the surface of GO and lead to quenched fluorescence. The method, designed in a simple “mix, incubate, and detect” format, can detect concentrations of Hg 2+ as low as 0.031 nM, and exhibit good selectivity and practical application.
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LIQUID CRYSTALS
·
2019
·
IF 3.078
Zirui Lin,Yuehua Cong,Baoyan Zhang,Haozhou Huang
A novel Y-shaped liquid crystalline epoxy with a rigid core with three flexible liquid crystalline arms (ETTPM) was synthesised and its structure was characterised by Fourier transform infrared spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. It was analysed and observed by differential scanning calorimetry, X-ray diffraction and polarised optical microscopy (POM) that the liquid crystal phase was stable on the temperature range of 107.8°C. In particular, an unusual transition phenomenon of liquid crystal phases was observed. Modified epoxy-resin-cured products were prepared using ETTPM, epoxy resin E51 and 4,4-diaminodiphenyl methane. The liquid crystalline domains in cured products were observed by researching their scattering effect on laser. Mechanical tests showed that ETTPM was effective for the mechanical properties improvement of epoxy-resin-cured products, as demonstrated in the improvement of impact strength, tensile strength and tensile elasticity modulus. The impact fracture cross-sections and surface morphologies were studied further by POM and scanning electron microscopy (SEM). Crack deformation, crack split and notable plastic deformations were found in modified epoxy-resin-cured products, and these factors played important roles in improving the impact strength.
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ANALYTICA CHIMICA ACTA
·
2014
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IF 4.517
Xia Hao,Jing Lei Lei,Nian Bing Li,Hong Qun Luo
A simple and effective method for the detection of electrochemically inactive sodium dodecyl sulfate (SDS) has been designed, based on different binding affinity of polyethyleneimine (PEI) toward electrochemically active eosin Y and electrochemically inactive SDS. The stronger binding affinity of the PEI toward SDS than eosin Y results in the decrease of the redox peak current of surface confined eosin Y and provides a quantitative readout for the SDS. The difference in value of the cathodic peak current showed a linear relationship with SDS concentration in a concentration range from 1 to 40 μg mL −1 , and a detection limit of 0.9 μg mL −1 for SDS was obtained. Furthermore, the method has been successfully applied to the detection of SDS in real samples. The developed approach provided a simple and reliable detection for SDS and might have potential applications in electrochemical methods for inactive molecules.
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PubMed
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