The Experts below are selected from a list of 42 Experts worldwide ranked by ideXlab platform
Ben Zhong Tang - One of the best experts on this subject based on the ideXlab platform.
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ferrocene based poly aroxycarbonyltriazole s synthesis by metal free click polymerization and use as precursors to Magnetic Ceramics
Polymer Chemistry, 2013Co-Authors: Jacky Wing Yip Lam, Ben Zhong Tang, Anjun Qin, Jing Zhi SunAbstract:Ferrocene-based poly(aroxycarbonyltriazole)s with high molecular weights and regioregularities were prepared in high yields by the efficient metal-free click polymerization of dipropiolates and the ferrocene-containing diazide under mild reaction conditions. The resulting polytriazoles are redox active, and could be used as precursors to generate soft Magnetic Ceramics with high magnetizability and low coercivity when pyrolyzed at elevated temperatures.
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ferrocene decorated hyperbranched poly aroxycarbonylphenylene s synthesis light refraction photopatterning and precursor to Magnetic Ceramics
Journal of Inorganic and Organometallic Polymers and Materials, 2013Co-Authors: Cathy Ka Wai Jim, Jacky Wing Yip Lam, Anjun Qin, Chris Wai Tung Leung, Liu Jianzhao, Herman H Y Sung, Ian D Williams, Ben Zhong TangAbstract:Ferrocene-decorated hyperbranched poly[1,3,5-tri(aroycarbonyl)phenylene]s (hb-PTACPs) are prepared in moderate yields with high molecular weights by one-pot polycyclotrimerization of 4,4′-isopropylidenediphenyl bipropiolate with 4-(ferrocenylmethyl)phenyl propiolate in reflux dimethylformamide. All the polymers are soluble and film-forming. They enjoy high thermal stability and lost little of their weight when heated to 300 °C under nitrogen. Thin solid films of the organometallic polymers shows high refractive indices (RI = 1.7038–1.6295) in the wavelength region of 400–1,700 nm. Ceramization of the organometallic hb-PTACPs at high temperature under inert atmosphere gives iron nanoparticles with high magnetizabilities. The organometallic polymers are readily crosslinked under UV irradiation and pyrolysis of the patterned polymer films produces Magnetic ceramic patterns with good shape retention.
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ferrocene functionalized hyperbranched polyphenylenes synthesis redox activity light refraction transition metal complexation and precursors to Magnetic Ceramics
Macromolecules, 2010Co-Authors: Jianbing Shi, Jacky Wing Yip Lam, Cathy Ka Wai Jim, Herman H Y Sung, Ian D Williams, Faisal Mahtab, Jianzhao Liu, Yuping Dong, Ben Zhong TangAbstract:New catalyst systems for diyne polycyclotrimerization were developed. E-1-[2-(2,5-Diethynylphenyl)vinyl]ferrocene (1), a ferrocene-containing diyne, was polymerized by ruthenium- and rhodium-based catalysts, affording hyperbranched polyphenylenes (hb-P1) with high molecular weights (Mw up to ∼1.4 × 105) in high yields (up to 100%). Effects of reaction conditions on the polymerization process were investigated, and structures of the resultant polymers were characterized by spectroscopic methods. The polymers were soluble, thermally stable, and redox active. Complexation with cobalt carbonyls further metalized the polymers. Both the polymers and their cobalt complexes showed high refractive indices (RI up to ∼1.81) at 300−1700 nm, large Abbe numbers (νD′ up to ∼681), and low optical dispersions (D′ down to ∼0.0015) in the telecommunication wavelength region. Pyrolyses of the polymers and their complexes furnished Magnetic Ceramics with high magnetizabilities (Ms up to ∼83 emu/g).
Misra S. - One of the best experts on this subject based on the ideXlab platform.
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EPR/FMR, FTIR, X-Ray and Raman investigations of Fe-Doped SiCN Ceramics
2020Co-Authors: Andronenko S., Menard D., Lacroix C., Misra S.Abstract:SiCN Magnetic Ceramics doped with Fe ions were synthesized at different pyrolysis temperatures in the range from 600 to 1600°C. Several phases of Ceramics were detected using the techniques of electron paraMagnetic resonance/ferroMagnetic resonance, Raman, Fourier-transform infrared and X-ray diffractometry, listed as follows: (a) transformation to the ceramic state from the polymer state, where the Fe ions are in the paraMagnetic state, as the temperature is increased from 600 to 800°C; (b) formation of two different Fe species in the range of 950-1150°C: nanocrystalline particles in the ferroMagnetic state and Fe ions incorporated into the free-carbon state in the superparaMagnetic state; (c) diminution of the free-carbon content above 1150°C, and, as a consequence, diminution of the intensity of the broad Fe signal related to this phase; (d) appearance of a new Fe phase at about 1200°C; (e) disappearance of the ferroMagnetic phase at about 1400°C; (f) disappearance of all Fe ions above 1530°C. The samples exhibiting superparaMagnetic behavior are potentially useful in developing high-temperature Magnetic sensor devices. © 2010 Springer
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EPR/FMR Investigation of Mn-Doped SiCN Ceramics
2020Co-Authors: Andronenko S., Leo A., Misra S.Abstract:SiCN Magnetic Ceramics doped with Mn 2+ ions were synthesized at the pyrolysis temperature of 1,100°C, using CERASET™ as liquid polymer precursor and polymer manganese(II) acetylacetonate as dopant, and investigated by electron paraMagnetic resonance (EPR)/ferroMagnetic resonance (FMR) technique. The predominant source of ferromagnetism in SiCN samples doped with Mn ions, as synthesized here, is the ensemble of ferroMagnetic nanoparticles of Mn 5Si 3C x incorporated into the amorphous SiC/Mn structure. The fluctuation of magnetization due to ferroMagnetic Mn 5Si 3C x particles significantly broadens the EPR lines at the phase-transition temperature (363 K). This is the first fabrication of a SiCN/Mn ceramic, which exhibits room-temperature ferromagnetism. © 2010 Springer-Verlag
Alejandro Várez - One of the best experts on this subject based on the ideXlab platform.
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microstructure Magnetic and mechanical properties of ni zn ferrites prepared by powder injection moulding
Powder Technology, 2011Co-Authors: J Gutierrezlopez, E Rodriguezsenin, M A Paris, J. Y. Pastor, Belén Levenfeld, A. Martin, Alejandro VárezAbstract:Nowadays, the electronic industry demands small and complex parts as a consequence of the miniaturization of electronic devices. Powder injection moulding (PIM) is an emerging technique for the manufacturing of Magnetic Ceramics. In this paper, we analyze the sintering process, between 900 °C and 1300 °C, of Ni–Zn ferrites prepared by PIM. In particular, the densification behaviour, microstructure and mechanical properties of samples with toroidal and bar geometry were analyzed at different temperatures. Additionally, the Magnetic behaviour (complex permeability and Magnetic losses factor) of these compacts was compared with that of samples prepared by conventional powder compaction. Finally, the mechanical behaviour (elastic modulus, flexure strength and fracture toughness) was analyzed as a function of the powder loading of feedstock. The final microstructure of prepared samples was correlated with the macroscopic behaviour. A good agreement was established between the densities and population of defects found in the materials depending on the sintering conditions. In general, the final mechanical and Magnetic properties of PIM samples were enhanced relative those obtained by uniaxial compaction.
Jacky Wing Yip Lam - One of the best experts on this subject based on the ideXlab platform.
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ferrocene based poly aroxycarbonyltriazole s synthesis by metal free click polymerization and use as precursors to Magnetic Ceramics
Polymer Chemistry, 2013Co-Authors: Jacky Wing Yip Lam, Ben Zhong Tang, Anjun Qin, Jing Zhi SunAbstract:Ferrocene-based poly(aroxycarbonyltriazole)s with high molecular weights and regioregularities were prepared in high yields by the efficient metal-free click polymerization of dipropiolates and the ferrocene-containing diazide under mild reaction conditions. The resulting polytriazoles are redox active, and could be used as precursors to generate soft Magnetic Ceramics with high magnetizability and low coercivity when pyrolyzed at elevated temperatures.
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ferrocene decorated hyperbranched poly aroxycarbonylphenylene s synthesis light refraction photopatterning and precursor to Magnetic Ceramics
Journal of Inorganic and Organometallic Polymers and Materials, 2013Co-Authors: Cathy Ka Wai Jim, Jacky Wing Yip Lam, Anjun Qin, Chris Wai Tung Leung, Liu Jianzhao, Herman H Y Sung, Ian D Williams, Ben Zhong TangAbstract:Ferrocene-decorated hyperbranched poly[1,3,5-tri(aroycarbonyl)phenylene]s (hb-PTACPs) are prepared in moderate yields with high molecular weights by one-pot polycyclotrimerization of 4,4′-isopropylidenediphenyl bipropiolate with 4-(ferrocenylmethyl)phenyl propiolate in reflux dimethylformamide. All the polymers are soluble and film-forming. They enjoy high thermal stability and lost little of their weight when heated to 300 °C under nitrogen. Thin solid films of the organometallic polymers shows high refractive indices (RI = 1.7038–1.6295) in the wavelength region of 400–1,700 nm. Ceramization of the organometallic hb-PTACPs at high temperature under inert atmosphere gives iron nanoparticles with high magnetizabilities. The organometallic polymers are readily crosslinked under UV irradiation and pyrolysis of the patterned polymer films produces Magnetic ceramic patterns with good shape retention.
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ferrocene functionalized hyperbranched polyphenylenes synthesis redox activity light refraction transition metal complexation and precursors to Magnetic Ceramics
Macromolecules, 2010Co-Authors: Jianbing Shi, Jacky Wing Yip Lam, Cathy Ka Wai Jim, Herman H Y Sung, Ian D Williams, Faisal Mahtab, Jianzhao Liu, Yuping Dong, Ben Zhong TangAbstract:New catalyst systems for diyne polycyclotrimerization were developed. E-1-[2-(2,5-Diethynylphenyl)vinyl]ferrocene (1), a ferrocene-containing diyne, was polymerized by ruthenium- and rhodium-based catalysts, affording hyperbranched polyphenylenes (hb-P1) with high molecular weights (Mw up to ∼1.4 × 105) in high yields (up to 100%). Effects of reaction conditions on the polymerization process were investigated, and structures of the resultant polymers were characterized by spectroscopic methods. The polymers were soluble, thermally stable, and redox active. Complexation with cobalt carbonyls further metalized the polymers. Both the polymers and their cobalt complexes showed high refractive indices (RI up to ∼1.81) at 300−1700 nm, large Abbe numbers (νD′ up to ∼681), and low optical dispersions (D′ down to ∼0.0015) in the telecommunication wavelength region. Pyrolyses of the polymers and their complexes furnished Magnetic Ceramics with high magnetizabilities (Ms up to ∼83 emu/g).
Andronenko S. - One of the best experts on this subject based on the ideXlab platform.
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EPR/FMR, FTIR, X-Ray and Raman investigations of Fe-Doped SiCN Ceramics
2020Co-Authors: Andronenko S., Menard D., Lacroix C., Misra S.Abstract:SiCN Magnetic Ceramics doped with Fe ions were synthesized at different pyrolysis temperatures in the range from 600 to 1600°C. Several phases of Ceramics were detected using the techniques of electron paraMagnetic resonance/ferroMagnetic resonance, Raman, Fourier-transform infrared and X-ray diffractometry, listed as follows: (a) transformation to the ceramic state from the polymer state, where the Fe ions are in the paraMagnetic state, as the temperature is increased from 600 to 800°C; (b) formation of two different Fe species in the range of 950-1150°C: nanocrystalline particles in the ferroMagnetic state and Fe ions incorporated into the free-carbon state in the superparaMagnetic state; (c) diminution of the free-carbon content above 1150°C, and, as a consequence, diminution of the intensity of the broad Fe signal related to this phase; (d) appearance of a new Fe phase at about 1200°C; (e) disappearance of the ferroMagnetic phase at about 1400°C; (f) disappearance of all Fe ions above 1530°C. The samples exhibiting superparaMagnetic behavior are potentially useful in developing high-temperature Magnetic sensor devices. © 2010 Springer
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EPR/FMR Investigation of Mn-Doped SiCN Ceramics
2020Co-Authors: Andronenko S., Leo A., Misra S.Abstract:SiCN Magnetic Ceramics doped with Mn 2+ ions were synthesized at the pyrolysis temperature of 1,100°C, using CERASET™ as liquid polymer precursor and polymer manganese(II) acetylacetonate as dopant, and investigated by electron paraMagnetic resonance (EPR)/ferroMagnetic resonance (FMR) technique. The predominant source of ferromagnetism in SiCN samples doped with Mn ions, as synthesized here, is the ensemble of ferroMagnetic nanoparticles of Mn 5Si 3C x incorporated into the amorphous SiC/Mn structure. The fluctuation of magnetization due to ferroMagnetic Mn 5Si 3C x particles significantly broadens the EPR lines at the phase-transition temperature (363 K). This is the first fabrication of a SiCN/Mn ceramic, which exhibits room-temperature ferromagnetism. © 2010 Springer-Verlag
