In the crystal engineering area,it is important to clearly demonstrating the relationship of structure and certain functionality.Herein,we present the study of the relationship of structure with phosphorescent nature ...In the crystal engineering area,it is important to clearly demonstrating the relationship of structure and certain functionality.Herein,we present the study of the relationship of structure with phosphorescent nature for two new room temperature phosphorescence(RTP) coordination polymers(CPs).[Pb(FDA)(H_(2)O)](1) and [NH_(3)(CH_(3))NH_(2)(CH_(3))_(2)][Pb_(4)(FDA)_(5)](2),where H_(2) FDA is 2,5-furandicarboxylic acid,have been synthesized by solvothermal method using different solvents and Pb^(2+) sources and characterized by microanalysis,powderX-ray diffraction(PXRD),thermogravimetric(TG),IR and UV-vis spectra.The Pb^(2+)ions adopt bicapped triangle prism coordination sphere in 1 and 2,which are connected together via FDA^(2-) ligands into bilayer structure in 1 while pillared-layer framework in 2.The FDA^(2-) ligands show different bridging modes in 1 and 2,leading to distinct coordination interactions between Pb^(2+) ion and FDA^(2-) ligand in both CPs.Both 1 and 2 emit ligand-centered RTP due to the heavy atom of Pb^(2+) ion,with a lifetime and quantum yield of 0.62 ms and 14.9% in 1 versus 1.69 ms and 15.7% in 2.The emission peak shows significant redshift(79 nm) in 2 regarding 1,which arises from their distinction of coordination interactions between Pb^(2+) ion and FDA^(2-) ligand in both CPs.展开更多
The anodic layer and oxygen evolution behavior of Pb-Ag-Nd alloy during pulse current polarization and constant current polarization in 160 g/L H2SO4 solution was comparatively investigated by chronopotentiometry, SEM...The anodic layer and oxygen evolution behavior of Pb-Ag-Nd alloy during pulse current polarization and constant current polarization in 160 g/L H2SO4 solution was comparatively investigated by chronopotentiometry, SEM, XRD, EIS and Tafel techniques. The results show that the anodic layer on Pb-Ag-Nd alloy formed through pulse current polarization is more intact and presents fewer micro-holes than that formed through constant current polarization. This could be attributed to the low current density period, which works as a ‘recovery period＇. During this period, the oxygen evolution reaction is less intense, which benefits the recovery of porous anodic layer. Pb-Ag-Nd anode also shows a lower anodic potential during pulse current polarization, which is in accordance with its smaller charge transfer resistance and smaller Tafel slope coefficient at high over-potential region. The lower anodic potential could be ascribed to the higher concentration of Pb O2 in the anodic layer, which promotes the formation of more reactive sites for the oxygen evolution reaction.展开更多
The application of semisolid process was investigated on Pb-Sb alloys that are normally used for metallic parts in car batteries, in order to increase their mechanical properties and corrosion resistance.The semisolid...The application of semisolid process was investigated on Pb-Sb alloys that are normally used for metallic parts in car batteries, in order to increase their mechanical properties and corrosion resistance.The semisolid behaviour of a Pb-4%Sb alloy was analysed by means of rheological and calorimetry differential scanning experiments.The alloy was melted, treated by ultrasound to obtain the semisolid state and then poured into permanent moulds.Some of these samples were also heated in semisolid temperature range and injected in thixo-casting apparatus.Both poured and injected samples were characterized by metallographic analysis, mechanical test and electrochemical corrosion experiments.The results show an improvement of mechanical and corrosion resistance with respect to samples obtained by conventional casting technique.展开更多
基金the National Natural Science Foundation of China (No.21901116)。
文摘In the crystal engineering area,it is important to clearly demonstrating the relationship of structure and certain functionality.Herein,we present the study of the relationship of structure with phosphorescent nature for two new room temperature phosphorescence(RTP) coordination polymers(CPs).[Pb(FDA)(H_(2)O)](1) and [NH_(3)(CH_(3))NH_(2)(CH_(3))_(2)][Pb_(4)(FDA)_(5)](2),where H_(2) FDA is 2,5-furandicarboxylic acid,have been synthesized by solvothermal method using different solvents and Pb^(2+) sources and characterized by microanalysis,powderX-ray diffraction(PXRD),thermogravimetric(TG),IR and UV-vis spectra.The Pb^(2+)ions adopt bicapped triangle prism coordination sphere in 1 and 2,which are connected together via FDA^(2-) ligands into bilayer structure in 1 while pillared-layer framework in 2.The FDA^(2-) ligands show different bridging modes in 1 and 2,leading to distinct coordination interactions between Pb^(2+) ion and FDA^(2-) ligand in both CPs.Both 1 and 2 emit ligand-centered RTP due to the heavy atom of Pb^(2+) ion,with a lifetime and quantum yield of 0.62 ms and 14.9% in 1 versus 1.69 ms and 15.7% in 2.The emission peak shows significant redshift(79 nm) in 2 regarding 1,which arises from their distinction of coordination interactions between Pb^(2+) ion and FDA^(2-) ligand in both CPs.
基金Projects(51204208,51374240)supported by the National Natural Science Foundation of ChinaProject(2012BAA03B04)supported by the National Science and Technology Pillar Program of ChinaProject(2014zzts028)supported by the Fundamental Research Funds for the Central Universities of Central South University,China
文摘The anodic layer and oxygen evolution behavior of Pb-Ag-Nd alloy during pulse current polarization and constant current polarization in 160 g/L H2SO4 solution was comparatively investigated by chronopotentiometry, SEM, XRD, EIS and Tafel techniques. The results show that the anodic layer on Pb-Ag-Nd alloy formed through pulse current polarization is more intact and presents fewer micro-holes than that formed through constant current polarization. This could be attributed to the low current density period, which works as a ‘recovery period＇. During this period, the oxygen evolution reaction is less intense, which benefits the recovery of porous anodic layer. Pb-Ag-Nd anode also shows a lower anodic potential during pulse current polarization, which is in accordance with its smaller charge transfer resistance and smaller Tafel slope coefficient at high over-potential region. The lower anodic potential could be ascribed to the higher concentration of Pb O2 in the anodic layer, which promotes the formation of more reactive sites for the oxygen evolution reaction.
文摘The application of semisolid process was investigated on Pb-Sb alloys that are normally used for metallic parts in car batteries, in order to increase their mechanical properties and corrosion resistance.The semisolid behaviour of a Pb-4%Sb alloy was analysed by means of rheological and calorimetry differential scanning experiments.The alloy was melted, treated by ultrasound to obtain the semisolid state and then poured into permanent moulds.Some of these samples were also heated in semisolid temperature range and injected in thixo-casting apparatus.Both poured and injected samples were characterized by metallographic analysis, mechanical test and electrochemical corrosion experiments.The results show an improvement of mechanical and corrosion resistance with respect to samples obtained by conventional casting technique.
