The present work investigates the effect of europium substitution on the （Bi, Pb）-2212 system in the concentration range 0.5 ≤ x ≤1.0. Phase analysis and lattice parameter calculations on the powder diffraction da...The present work investigates the effect of europium substitution on the （Bi, Pb）-2212 system in the concentration range 0.5 ≤ x ≤1.0. Phase analysis and lattice parameter calculations on the powder diffraction data and the elemental analysis of EDX show that the Eu atoms are successfully substituted into the （Bi, Pb）-2212 system. Resistivity measurements （64-300 K） reveal that the system exhibits superconductivity at x ≤ 0.5 and semiconductivity at x 〉 0.5. With the complete suppression of superconductivity which is known to be a quasi-two dimensional phenomenon in these materials, a metal to insulator transition takes place at x = 0.6 and the predominant conduction mechanism is found to be variable range hopping between localized states, resulting in macroscopic semiconducting behaviour. The results of electrical and structural properties of the doped （Bi, Pb）-2212 compounds suggest that the decrease of charge carrier concentration and the induced structural disorder are the more effective and dominant mechanisms in the origin of the metal to insulator transition and suppression of superconductivity due to Eu substitution at its Sr site.展开更多
The current work describes the synthesis of a new bio-waste derived cellulosic-carbon supportedpalladium nanoparticles enriched magnetic nanocatalyst(Pd/Fe_(3)O_(4)@C)using a simple multi-step process under aerobic co...The current work describes the synthesis of a new bio-waste derived cellulosic-carbon supportedpalladium nanoparticles enriched magnetic nanocatalyst(Pd/Fe_(3)O_(4)@C)using a simple multi-step process under aerobic conditions.Under mild reaction conditions,the Pd/Fe_(3)O_(4)@C magnetic nanocatalyst demonstrated excellent catalytic activity in the Hiyama cross-coupling reaction for a variety of substrates.Also,the Pd/Fe_(3)O_(4)@C magnetic nanocatalyst exhibited excellent catalytic activity up to five recycles without significant catalytic activity loss in the Hiyama cross-coupling reaction.Also,we explored the use of Pd/Fe_(3)O_(4)@C magnetic nanocatalyst as an electrocatalyst for hydrogen evolution reaction.Interestingly,the Pd/Fe_(3)O_(4)@C magnetic nanocatalyst exhibited better electrochemical activity compared to bare carbon and magnetite(Fe_(3)O_(4)nanoparticles)with an overpotential of 293 mV at a current density of 10 mA·cm^(–2).展开更多
基金supported by Kerala State Council for Science,Technology and Environment,Council of Scientific and Industrial Researchthe University Grants Commission of India
文摘The present work investigates the effect of europium substitution on the （Bi, Pb）-2212 system in the concentration range 0.5 ≤ x ≤1.0. Phase analysis and lattice parameter calculations on the powder diffraction data and the elemental analysis of EDX show that the Eu atoms are successfully substituted into the （Bi, Pb）-2212 system. Resistivity measurements （64-300 K） reveal that the system exhibits superconductivity at x ≤ 0.5 and semiconductivity at x 〉 0.5. With the complete suppression of superconductivity which is known to be a quasi-two dimensional phenomenon in these materials, a metal to insulator transition takes place at x = 0.6 and the predominant conduction mechanism is found to be variable range hopping between localized states, resulting in macroscopic semiconducting behaviour. The results of electrical and structural properties of the doped （Bi, Pb）-2212 compounds suggest that the decrease of charge carrier concentration and the induced structural disorder are the more effective and dominant mechanisms in the origin of the metal to insulator transition and suppression of superconductivity due to Eu substitution at its Sr site.
基金The authors thank DST-SERB,India(YSS/2015/000010)DST-Nanomission,India(SR/NM/NS-20/2014)Jain University,India for financial support.
文摘The current work describes the synthesis of a new bio-waste derived cellulosic-carbon supportedpalladium nanoparticles enriched magnetic nanocatalyst(Pd/Fe_(3)O_(4)@C)using a simple multi-step process under aerobic conditions.Under mild reaction conditions,the Pd/Fe_(3)O_(4)@C magnetic nanocatalyst demonstrated excellent catalytic activity in the Hiyama cross-coupling reaction for a variety of substrates.Also,the Pd/Fe_(3)O_(4)@C magnetic nanocatalyst exhibited excellent catalytic activity up to five recycles without significant catalytic activity loss in the Hiyama cross-coupling reaction.Also,we explored the use of Pd/Fe_(3)O_(4)@C magnetic nanocatalyst as an electrocatalyst for hydrogen evolution reaction.Interestingly,the Pd/Fe_(3)O_(4)@C magnetic nanocatalyst exhibited better electrochemical activity compared to bare carbon and magnetite(Fe_(3)O_(4)nanoparticles)with an overpotential of 293 mV at a current density of 10 mA·cm^(–2).
