Synthesis and evolution of ultrafine Ca2Fe2O5 nanoparticles via liquid-fed aerosol flame

Abstract

Flame synthesis is increasingly employed in the fabrication of multi-component functional nanoparticles. This study introduces a pioneering methodology for synthesizing ultrafine calcium ferrite (CaFeO) nanoparticles, with an average diameter of 8.5 nm, utilizing the liquid-fed aerosol flame method for the first time. Subsequently, a comprehensive exploration into the synthesis, evolution, and growth mechanism of these nanoparticles is undertaken. The influence of distinct solvent formulations, encompassing ethanol, n-heptane, and ethyl acetate is studied. Morphology and structure of CaFeO nanoparticles with ethyl acetate solvent is systematically examined with the thermophoretic sampling particle diagnostics. It has been demonstrated that CaFeO nanoparticles synthesized with ethyl acetate manifest heightened crystallinity and a uniform particle size below 10 nm, presenting a marked contrast to nanoparticles synthesized with ethanol and -heptane solvents, which predominantly exhibit non-uniform, amorphous large particles. Analysis of particle sampling results reveals an increase in average particle diameter from 4 nm to 9 nm, with particle collision identified as the primary growth mode. Multiple measurements of lattice spacings, elemental analysis, and crystal planes analysis confirm the well-crystallized nature of CaFeO particles throughout the growth process. The stage of CaFeO nanoparticles evolution is delineated, highlighting that the utilization of ethyl acetate as a solvent favors the gas-to-particle route. The revelation of ethyl acetate solvent promoting the gas-to-particle route opens new avenues for precise control in flame synthesis, especially for producing complex multifunctional nanoparticles with nano size, emphasizing the pivotal role of solvent selection and its consequential impact on the synthesis process, providing valuable insights for advancing the field of flame synthesis of nanomaterials.