The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Mingxu Zhang - One of the best experts on this subject based on the ideXlab platform.
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study on Dielectric properties of high organic sulfur coking coal and modeling sulfur compounds
PLOS ONE, 2019Co-Authors: Chuanchuan Cai, Mingxu ZhangAbstract:Coking coal is geologically scarce resource and most of them cannot be directly used in steel making due to their higher sulfur content. One desulfurization method that has great potential for massive application is microwave desulfurization, which removes the relatively stubborn organic sulfur under mild conditions. The Dielectric properties of coals determine the efficiency of the microwave energy absorption. The key to describing the mechanism of microwave desulfurization and further improvement of the desulfurization efficiency is the Dielectric response of organic sulfur compounds in coal to microwave. This study focuses on existing formand microwave response of organic sulfur components of three typical coking coal in China. Resultsshowed that the major organic sulfur in selected coals is thiophene which has a stable structure and is the most difficult to be removed. Several Dielectric peaks (Dielectric loss)andsignificant differencesofeach selected coal samples are observed. The microwave absorption peaks of the model sulfur compounds are identified to be within 9-11GHz. The real parts of the relative Dielectric constants (hereinafter referred to as e′) shows a decreasing trend as: diphenyl sulfoxide > diphenyl sulfone > diphenyl sulfide > dibenzothiophene > Octadecane thiol. Response to microwaveare observed to be distinctively different between sulfur-containing and sulfur-free model compounds. The Dielectric Polarization of mixture (coal mixed with model sulfur compounds) is greater than pure coal. Meanwhile the higher the sulfur content of the coal, the greater the e′ is. Sulfur componentsin coal can significantly influence its Polarization.
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Study on Dielectric properties of high organic sulfur coking coal and modeling sulfur compounds
2019Co-Authors: Chuanchuan Cai, Mingxu ZhangAbstract:Coking coal is geologically scarce resource and most of them cannot be directly used in steel making due to their higher sulfur content. One desulfurization method that has great potential for massive application is microwave desulfurization, which removes the relatively stubborn organic sulfur under mild conditions. The Dielectric properties of coals determine the efficiency of the microwave energy absorption. The key to describing the mechanism of microwave desulfurization and further improvement of the desulfurization efficiency is the Dielectric response of organic sulfur compounds in coal to microwave. This study focuses on existing formand microwave response of organic sulfur components of three typical coking coal in China. Resultsshowed that the major organic sulfur in selected coals is thiophene which has a stable structure and is the most difficult to be removed. Several Dielectric peaks (Dielectric loss)andsignificant differencesofeach selected coal samples are observed. The microwave absorption peaks of the model sulfur compounds are identified to be within 9-11GHz. The real parts of the relative Dielectric constants (hereinafter referred to as ε′) shows a decreasing trend as: diphenyl sulfoxide > diphenyl sulfone > diphenyl sulfide > dibenzothiophene > Octadecane thiol. Response to microwaveare observed to be distinctively different between sulfur-containing and sulfur-free model compounds. The Dielectric Polarization of mixture (coal mixed with model sulfur compounds) is greater than pure coal. Meanwhile the higher the sulfur content of the coal, the greater the ε′ is. Sulfur componentsin coal can significantly influence its Polarization.
Chuanchuan Cai - One of the best experts on this subject based on the ideXlab platform.
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study on Dielectric properties of high organic sulfur coking coal and modeling sulfur compounds
PLOS ONE, 2019Co-Authors: Chuanchuan Cai, Mingxu ZhangAbstract:Coking coal is geologically scarce resource and most of them cannot be directly used in steel making due to their higher sulfur content. One desulfurization method that has great potential for massive application is microwave desulfurization, which removes the relatively stubborn organic sulfur under mild conditions. The Dielectric properties of coals determine the efficiency of the microwave energy absorption. The key to describing the mechanism of microwave desulfurization and further improvement of the desulfurization efficiency is the Dielectric response of organic sulfur compounds in coal to microwave. This study focuses on existing formand microwave response of organic sulfur components of three typical coking coal in China. Resultsshowed that the major organic sulfur in selected coals is thiophene which has a stable structure and is the most difficult to be removed. Several Dielectric peaks (Dielectric loss)andsignificant differencesofeach selected coal samples are observed. The microwave absorption peaks of the model sulfur compounds are identified to be within 9-11GHz. The real parts of the relative Dielectric constants (hereinafter referred to as e′) shows a decreasing trend as: diphenyl sulfoxide > diphenyl sulfone > diphenyl sulfide > dibenzothiophene > Octadecane thiol. Response to microwaveare observed to be distinctively different between sulfur-containing and sulfur-free model compounds. The Dielectric Polarization of mixture (coal mixed with model sulfur compounds) is greater than pure coal. Meanwhile the higher the sulfur content of the coal, the greater the e′ is. Sulfur componentsin coal can significantly influence its Polarization.
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Study on Dielectric properties of high organic sulfur coking coal and modeling sulfur compounds
2019Co-Authors: Chuanchuan Cai, Mingxu ZhangAbstract:Coking coal is geologically scarce resource and most of them cannot be directly used in steel making due to their higher sulfur content. One desulfurization method that has great potential for massive application is microwave desulfurization, which removes the relatively stubborn organic sulfur under mild conditions. The Dielectric properties of coals determine the efficiency of the microwave energy absorption. The key to describing the mechanism of microwave desulfurization and further improvement of the desulfurization efficiency is the Dielectric response of organic sulfur compounds in coal to microwave. This study focuses on existing formand microwave response of organic sulfur components of three typical coking coal in China. Resultsshowed that the major organic sulfur in selected coals is thiophene which has a stable structure and is the most difficult to be removed. Several Dielectric peaks (Dielectric loss)andsignificant differencesofeach selected coal samples are observed. The microwave absorption peaks of the model sulfur compounds are identified to be within 9-11GHz. The real parts of the relative Dielectric constants (hereinafter referred to as ε′) shows a decreasing trend as: diphenyl sulfoxide > diphenyl sulfone > diphenyl sulfide > dibenzothiophene > Octadecane thiol. Response to microwaveare observed to be distinctively different between sulfur-containing and sulfur-free model compounds. The Dielectric Polarization of mixture (coal mixed with model sulfur compounds) is greater than pure coal. Meanwhile the higher the sulfur content of the coal, the greater the ε′ is. Sulfur componentsin coal can significantly influence its Polarization.
Stephen J Pennycook - One of the best experts on this subject based on the ideXlab platform.
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gigahertz Dielectric Polarization of substitutional single niobium atoms in defective graphitic layers
Physical Review Letters, 2015Co-Authors: Xuefeng Zhang, Junjie Guo, Pengfei Guan, Gaowu Qin, Stephen J PennycookAbstract:We synthesize two Nb/C composites with an order of magnitude difference in the density of single niobium atoms substituted into defective graphitic layers. The concentration and sites of single Nb atoms are identified using aberration-corrected scanning transmission electron microscopy and density functional theory. Comparing the experimental complex permittivity spectra reveals that a representative Dielectric resonance at ∼16 GHz originates from the intrinsic Polarization of single Nb atom sites, which is confirmed by theoretical simulations. The single-atom Dielectric resonance represents the physical limit of the electromagnetic response of condensed matter, and thus might open up a new avenue for designing electromagnetic wave absorption materials. Single-atom resonance also has important implications in understanding the correlation between the macroscopic Dielectric behaviors and the atomic-scale structural origin.
Ram Jeewan Sengwa - One of the best experts on this subject based on the ideXlab platform.
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Effects of different inorganic nanoparticles on the structural, Dielectric and ion transportation properties of polymers blend based nanocomposite solid polymer electrolytes
Electrochimica Acta, 2017Co-Authors: Shobhna Choudhary, Ram Jeewan SengwaAbstract:Abstract Nanocomposite solid polymer electrolyte (NSPE) films consisted of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) blend (50/50 wt%) as host polymer matrix with 20 wt% lithium perchlorate (LiClO 4 ) as dopant salt and 3 wt% inorganic nanoparticles (i.e., Al 2 O 3 , SiO 2 , SnO 2 or ZnO) as filler have been prepared by solution cast method followed by melt-press technique. The X-ray diffraction (XRD) study confirms that the electrolyte films without nanofiller and with Al 2 O 3 and SiO 2 nanofillers have predominantly amorphous structures, whereas the characteristic diffraction peaks of SnO 2 and ZnO crystallites are observed in the respective NSPEs. Fourier transform infra-red (FTIR) spectra of these NSPE films confirm the formation of ion-dipolar coordination between the functional groups of polymers and the lithium ions throughout the material which completely suppressed the crystalline region absorption peaks of the PEO. The metal oxides of the nanoparticles mainly exhibit van der Waals type interaction with the polymers chains and the ions in the NSPE materials. Effects of a lithium salt as a dopant and the nanoparticles as fillers on the crystalline phase and thermal behaviour of PEO–PMMA blend in these electrolyte materials have also been examined by their differential scanning calorimetry (DSC) measurements. Dielectric and electrical dispersion behaviour of the NSPE films have been characterized by employing Dielectric relaxation spectroscopy (DRS) over the frequency range from 20 Hz to1 MHz and at temperatures 27, 35, 45 and 55 °C. The single relaxation peak appeared in the Dielectric loss tangent spectra of these electrolytes confirms the ion-dipolar coordinated coupled cooperative chain segmental motion of the PEO and PMMA macromolecules. Lowering in the values of Dielectric Polarization strength and ionic conductivity has been observed for all the NSPE films as compared to that of the SPE film without nanofiller. A linear correlation between the crystallite sizes of different nanofillers and the Dielectric permittivity of NSPE materials has been revealed. It is found that the cooperative polymers chain segmental dynamics becomes slower with the dispersion of nanoparticles in the ion-dipolar complexes which causes a decrease of ionic conductivity of the NSPE films. The correlation observed between the Dielectric relaxation time and the ionic conductivity confirms that the ions transport occurs by intra- and inter-chain hopping in these PEO–PMMA blend based electrolytes. Temperature dependent values of relaxation time and dc ionic conductivity of the electrolyte films obey the Arrhenius relation and their activation energies are found in the range 0.22 eV to 0.40 eV which differ with the types of inorganic nanoparticles dispersed in the NSPEs. The comparative results confirm that the polymers chain segmental dynamics mask the effect of amorphous phase of these materials which contributes in the lithium ions transportation and their mobility. Linear correlation observed between the Dielectric permittivity and ionic conductivity values of these NSPEs suggests that the strength of Dielectric Polarization also plays an important role for the ion transportation process in the solid ion-dipolar complexes. The room temperature ionic conductivity values of these NSPE films are found of the order of 10 −5 S cm −1 which confirms their suitability as potential candidates in the design and development of all-solid-state devices including the rechargeable lithium-ion batteries. Finally, these experimental results explain in depth the fundamental issues of nanomaterials science that confront the use of various kind of inorganic nanoparticles in the preparation of NSPEs, and the dependence of their ion transportation process on the amorphous phase, Dielectric permittivity and the cooperative polymers chain segmental motion, especially for the polymers blend based electrolytes.
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temperature dependent static Dielectric constant and viscosity behaviour of glycerol amide binary mixtures characterization of dominant complex structures in Dielectric Polarization and viscous flow processes
Journal of Molecular Liquids, 2010Co-Authors: Ram Jeewan Sengwa, Vinita Khatri, Shobhna Choudhary, Sonu SankhlaAbstract:Abstract The static Dielectric constant and viscosity of the binary mixtures of glycerol (Gly) with N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMA) were measured over the entire composition range at temperatures 288.15, 303.15, 318.15 and 333.15 K. The concentration dependent non-linear behaviour of the measured thermodynamical parameters revealed the formation of hydrogen bond interactions between glycerol and amide molecules with a variety of complexes. The excess Dielectric constant and excess viscosity were determined and analyzed for the confirmation of the composition of dominant complex species. Results inferred that the Dielectric Polarization in both the Gly–DMF and Gly–DMA mixtures is governed by 1:1 complex species with enhanced dipolar ordering at all the investigated temperatures. The complex species of 3Gly:DMF and 2Gly:DMA facilitates the viscous flow process in Gly–DMF and Gly–DMA mixtures, respectively and the density of these species is strongly influenced by the change in temperature. Arrhenius type behaviour of viscosity against the reciprocal of temperature was used to determine the apparent activation energy of the viscous flow. The electric-field-induced increment of the Helmholtz free energy and the entropy were determined from the temperature dependence of the static Dielectric constant and its derivative of the binary mixtures. Results were discussed to assess the volume effect of DMF and DMA molecules on hydrogen bonding interactions with glycerol molecules in order to confirm the structural conformations of these mixed solvents.
Wei Wang - One of the best experts on this subject based on the ideXlab platform.
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temperature dependence of Dielectric Polarization and strain behaviors for rhombohedral pimnt single crystal with different crystallographic orientations
Journal of Alloys and Compounds, 2012Co-Authors: Wei Wang, Chung Ming Leung, Jie Jiao, Yaoyao Zhang, Xiangyong Zhao, Haosu LuoAbstract:Abstract In this study, the Dielectric, ferroelectric and strain behaviors of 0.35Pb(In1/2Nb1/2)O3–0.35Pb(Mg1/3Nb2/3)O3–0.30PbTiO3 (0.35PIN–0.35PMN–0.30PT or PIMNT35/35/30) single crystal with different crystallographic orientations were investigated as a function of temperature. The Curie temperature TC and rhombohedral to tetragonal phase transition temperature Trt were risen up to 188 °C and 120 °C, respectively. The coercive field EC and remnant Polarization Pr for 〈0 0 1〉 and 〈1 1 0〉 oriented crystals were found to be 5.8 kV/cm, 27.5 μC/cm2 and 8.5 kV/cm, 38.7 μC/cm2 at room temperature, respectively. The Polarization data were obtained from the hysteresis loops of the crystal measured in a wide temperature range. The unipolar strain level was found to be 0.65% at an electric field of 32 kV/cm, with piezoelectric strain coefficient d33 ∼ 2000 pC/N for 〈0 0 1〉 oriented crystal. Besides, the intermediate metastable state was induced at an electric field of 12.5 kV/cm for 〈1 1 0〉 oriented crystal, which can be utilized in large power transducers such as sonar and actuator.