Synthesis of nanoparticles in a flame aerosol reactor with independent and strict control oftheir size, crystal phase and morphology

Abstract

A flame aerosol reactor (FLAR) was developed to synthesize nanoparticles with desired properties(crystal phase and size) that could be independently controlled. The methodology was demonstratedfor TiO2 nanoparticles, and this is the first time that large sets of samples with the same size but differentcrystal phases (six different ratios of anatase to rutile in this work) were synthesized. The degree ofTiO2 nanoparticle agglomeration was determined by comparing the primary particle sizedistribution measured by scanning electron microscopy (SEM) to the mobility-based particlesize distribution measured by online scanning mobility particle spectrometry (SMPS). Bycontrolling the flame aerosol reactor conditions, both spherical unagglomerated particlesand highly agglomerated particles were produced. To produce monodisperse nanoparticles,a high throughput multi-stage differential mobility analyser (MDMA) was used in serieswith the flame aerosol reactor. Nearly monodisperse nanoparticles (geometricstandard deviation less than 1.05) could be collected in sufficient mass quantities (ofthe order of 10 mg) in reasonable time (1 h) that could be used in other studiessuch as determination of functionality or biological effects as a function of size.