Metal nanoparticle generation using a small ceramic heater with a local heating area

摘要

Metal nanoparticles were synthesized by evaporation/condensation using a small ceramic heater with a local heating area.Many previous studies have reported generating nanoparticles using the tube-furnace evaporation/condensation method.However,this approach has several drawbacks in terms of aerosol generator applications,because a large space is required to set up the system and high energy consumption is needed to raise the environmental temperature around the source material.This process also requires significant time to establish thermal stability.We investigated the synthesis of metal nanoparticles using a small ceramic heater,noted the properties of the resultant nanoparticles,and evaluated the approach's performance.The small ceramic heater has a local heating area where source metals can be evaporated.The heater is capable of reaching about 1500 deg C in about 10 s at a local heating area of 5 x 10 mm~2.Silver(Ag)was selected as the source material.The size distributions of the prepared particles were measured with an SMPS system at various surface temperatures.For a detailed analysis of various properties,such as morphology,phase composition,and crystallinity,the sampled nanoparticles were investigated by TEM and XRD analysis.The results show that the geometric mean diameter,the geometric standard deviation,and the total number concentration of nanoparticles increase with heater surface temperature.The particle generation was very stable,because the temperature of the heater surface does not fluctuate with time.From the TEM images and XRD analysis,it was revealed that the Ag nanoparticles were spherical and nonagglomerated.Pure silver was obtained,despite the fact that air was used as a carrier gas.