Study On The Heat Resistance And Stability Of Silver Nanowires

Silver nanowires(Ag NWs)have various advantages,such as excellent mechanical strength,good flexibility,and high transparency and high conductivity.They can be produced at low cost and in large scale and are widely used in various electronic devices.Therefore,the transition between one-dimensional wires and zero-dimensional particles is of great significance for the application of nanomaterials.As we all know,due to the obvious small size effect and surface(boundary)surface effect of nanomaterials,their surface activity is high,and the phenomenon of atomic diffusion is serious under low temperature conditions.Therefore,the melting temperature of Ag NWs is much lower than that of bulk silver(961.3 ?).Many studies have shown that Ag NWs will break into silver nanorods at a lower temperature,and as the temperature continues to rise,the silver nanorods gradually spheroidize and form silver nanoparticles.The existence of this thermodynamic instability may seriously hinder the reliability of the metal element,which brings great challenges to the long-term stability of Ag NWs in products.For this reason,it is imperative to study the stability of Ag NWs,to explore the root causes and regularity of the degradation of Ag NWs,so as to obtain methods to adjust and control their instability,so that unstable lines can occur in a controlled manner.This paper mainly takes the instability of Ag NWs as the starting point,and studies the heat resistance of Ag NWs under different atmospheres and different forms of Ag NWs.Combined with SEM analysis found: the critical temperature of the Ag NWs that are thermally annealed in the oxygen atmosphere and the atmospheric atmosphere to be completely broken into nanochains is 400 °C with the same diameter,which is lower than the critical temperature of 450 °C in the Ar atmosphere;The critical temperature of a single Ag NWs completely broken into nanochains is 400 ?,which is lower than the critical temperature of the Ag NWs network 450 ?;The critical temperature of theAg NWs after plastic deformation to be completely broken into nanochains is 400 ?,which is lower than the critical temperature of the Ag NWs without plastic deformation of450 ?;The larger diameter Ag NWs has better heat resistance than the smaller diameter Ag NWs,and under sufficient heating conditions,the thermal performance of Ag NWs is almost independent of the time parameter,but mainly related to the temperature parameter.This article also introduces the Ag NWs ultrasonic pressure welding process.In the experiment,the Ag NWs with plastic deformation and without plastic deformation were placed in a vacuum environment and atmospheric environment for a long time to explore their morphological changes under different conditions.The study found that Ag NWs without plastic deformation and Ag NWs with plastic deformation experienced surface roughening after being placed in a vacuum environment and the atmosphere for 6months.And in vacuum environment,the surface roughness of Ag NWs with 30 nm diameter with plastic deformation and without plastic deformation is the most serious,while the surface roughening with Ag NWs with 90 nm diameter with plastic deformation and without plastic deformation is the most serious in the atmospheric environment.Through comparative experiments,it can be seen that placing Ag NWs in a vacuum environment can effectively slow down its roughening rate,and Ag NWs will undergo silver atom migration during long-term storage,and the atomic migration rate of plastically deformed Ag NWs is higher than that without plastic deformation.In this study,Ag NWs doped with other silver nanomaterials was used in conductive adhesives to study the influence of doped silver nanomaterials on the heat resistance of Ag NWs and the corresponding changes in conductive properties.The results show that Ag NWs mixed with silver nanoparticles(Ag NPs)or silver micro-flake(Ag MFs)are used to prepare conductive adhesives and both mixed Ag NPs and Ag MFs will reduce the heat resistance of Ag NWs in conductive adhesives,and Ag MFs have higher impact than Ag NPs.However,Ag NPs and Ag MFs can improve the stability of Ag NWs in the conductive adhesive.The Ag NWs doped with Ag NPs or Ag MFs in the conductive adhesive had no obvious change after 6 months of storage,and the undoped Ag NWs hada certain morphological change.This study also found that the volume resistivity of conductive adhesives with different fillers first decreased and then increased with the increase of temperature,and after being placed at room temperature for 6 months,the volume resistivity of these conductive adhesives decreased.