The microstructure and microhardness of Sn-3.5%Ag solders were explored in the cooling rate ranging from 0.08 to 104 K/s. Under rapid cooling condition, the strong kinetic undercooling effect leads to the actual solid...The microstructure and microhardness of Sn-3.5%Ag solders were explored in the cooling rate ranging from 0.08 to 104 K/s. Under rapid cooling condition, the strong kinetic undercooling effect leads to the actual solidification process starting at the temperature lower than the equilibrium eutectic point, and the actual metastable eutectic point shifts to the higher Ag concentration. Hence, the higher the applied cooling rate is, the more the volume fraction of primary β-Sn crystal forms. At the same time, the separation of primary β-Sn crystal favors restraining the formation of bulk Ag3Sn intermetallic compounds (IMCs) in solder due to the mismatch crystalline orientation relationship, those Ag3Sn phase separating through the eutectic reaction could hardly cling to the primary β-Sn crystal and grow up. Additionally, the Vickers hardness test shows that fine β-Sn and spherical Ag3Sn phase in the rapidly solidified alloy strongly improves the microhardness of the Sn-3.5%Ag solder.展开更多
The exploitation of new green polymerization avenues for the effective synthesis of polymers by reversible-deactivation radical polymerization plays a critical role in pursuing the development of polymeric materials.I...The exploitation of new green polymerization avenues for the effective synthesis of polymers by reversible-deactivation radical polymerization plays a critical role in pursuing the development of polymeric materials.In this work,serials of deep eutectic solvents(DES)with intermolecular-hydrogen-bonding interaction were constructed as catalysts and medium for actuating reversible complexation-mediated polymerization(RCMP)for the first time,yielding methacrylate polymers with high monomer conversion and narrow dispersion molecular weight in both water and oil systems.The mechanism and elementary reaction of RCMP were explored deeply,revealing that the complexation of initiator with DES to generate radicals was a ratecontrolling step and intermolecular-hydrogen-bond was primary factor to influence polymerization rate.Moreover,the insights of density functional theory calculations revealed that negative electrostatic potential ensured nucleophilic capacity.This investigation demonstrated the considerable potential of DES for RCMP,which is anticipated for other polymerization applications as a novel medium mode.展开更多
As an oxygen reduction reaction(ORR)catalyst,nitrogen-doped carbon(NC)is widely used in zinc-air batteries(ZABs).However,NC catalysts exhibit low conductivity and insufficient exposure of active sites.Therefore,a Co-b...As an oxygen reduction reaction(ORR)catalyst,nitrogen-doped carbon(NC)is widely used in zinc-air batteries(ZABs).However,NC catalysts exhibit low conductivity and insufficient exposure of active sites.Therefore,a Co-based deep eutectic solvent(DES)was selected to modify NC catalyst(Co-NC)to improve ORR performances.Density functional theory(DFT)calculation shows that the modification of Co-based DES can change the electronic structure of NC and increase metallic active sites,which is beneficial to the desorption of reaction intermediates on Co-NC,further improving ORR performance.Co-NC shows excellent ORR performances and stability.Impressively,ZABs assembled with Co-NC manifest a high maximum power density of 177.4 mW cm^(-2),a high specific capacity of 726.12 mA h g^(-1)and a charge-discharge cycle life of 500 h.This study can provide practical reference for surface modified carbon-based electrocatalyst with DES to improve ORR performances.展开更多
基金Project(50401033) supported by the National Natural Science Foundation of China Project(200335) supported by the Foundation for the Author of National Excellent Doctoral Dissertation of China+1 种基金 Project(033608811) supported by the Natural Science Foundation of Tianjin City, China Project supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry
文摘The microstructure and microhardness of Sn-3.5%Ag solders were explored in the cooling rate ranging from 0.08 to 104 K/s. Under rapid cooling condition, the strong kinetic undercooling effect leads to the actual solidification process starting at the temperature lower than the equilibrium eutectic point, and the actual metastable eutectic point shifts to the higher Ag concentration. Hence, the higher the applied cooling rate is, the more the volume fraction of primary β-Sn crystal forms. At the same time, the separation of primary β-Sn crystal favors restraining the formation of bulk Ag3Sn intermetallic compounds (IMCs) in solder due to the mismatch crystalline orientation relationship, those Ag3Sn phase separating through the eutectic reaction could hardly cling to the primary β-Sn crystal and grow up. Additionally, the Vickers hardness test shows that fine β-Sn and spherical Ag3Sn phase in the rapidly solidified alloy strongly improves the microhardness of the Sn-3.5%Ag solder.
基金financially supported by the State Key Program of National Natural Science Foundation of China(U21A20313)the Key Program of Qingyuan Innovation Laboratory(00221003)+2 种基金the“111”Program of Fuzhou Universitythe Natural Science Foundation of Fujian Province(2019J05040)the China Postdoctoral Science Foundation(2022M20739)。
文摘The exploitation of new green polymerization avenues for the effective synthesis of polymers by reversible-deactivation radical polymerization plays a critical role in pursuing the development of polymeric materials.In this work,serials of deep eutectic solvents(DES)with intermolecular-hydrogen-bonding interaction were constructed as catalysts and medium for actuating reversible complexation-mediated polymerization(RCMP)for the first time,yielding methacrylate polymers with high monomer conversion and narrow dispersion molecular weight in both water and oil systems.The mechanism and elementary reaction of RCMP were explored deeply,revealing that the complexation of initiator with DES to generate radicals was a ratecontrolling step and intermolecular-hydrogen-bond was primary factor to influence polymerization rate.Moreover,the insights of density functional theory calculations revealed that negative electrostatic potential ensured nucleophilic capacity.This investigation demonstrated the considerable potential of DES for RCMP,which is anticipated for other polymerization applications as a novel medium mode.
基金supported by the National Natural Science Foundation of China(No,22278193)the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘As an oxygen reduction reaction(ORR)catalyst,nitrogen-doped carbon(NC)is widely used in zinc-air batteries(ZABs).However,NC catalysts exhibit low conductivity and insufficient exposure of active sites.Therefore,a Co-based deep eutectic solvent(DES)was selected to modify NC catalyst(Co-NC)to improve ORR performances.Density functional theory(DFT)calculation shows that the modification of Co-based DES can change the electronic structure of NC and increase metallic active sites,which is beneficial to the desorption of reaction intermediates on Co-NC,further improving ORR performance.Co-NC shows excellent ORR performances and stability.Impressively,ZABs assembled with Co-NC manifest a high maximum power density of 177.4 mW cm^(-2),a high specific capacity of 726.12 mA h g^(-1)and a charge-discharge cycle life of 500 h.This study can provide practical reference for surface modified carbon-based electrocatalyst with DES to improve ORR performances.
