A thermochemical pathway for controlled synthesis of AlN nanoparticles in non-isothermal conditions

Highlights: • A non-isothermal combustion process was developed for synthesizing AlN nanoparticles. • Temperature-time profiles and combustion parameters were recorded and discussed. • AlN nanoparticles (50–200 nm) with a specific surface of 7.9–20.8 m²/g were prepared. • The thermochemical mechanism of AlN formation in the combustion wave was clarified. - Abstract: The synthesis of AlN nanoparticles in non-isothermal high-temperature conditions was developed. The process involved Al₂O₃–Mg–NH₄Cl mixtures preparation and combustion in nitrogen atmosphere. Temperature profiles in the combustion waves were recorded by thermocouples, and the values of combustion temperature and wave velocity were determined from the recorded profiles. The existence of two independed combustion regimes with maximum temperatures of about 850 °C and 1400–1600 °C were revealed based on concentrations of NH₄Cl. AlN nanocrystals were obtained and investigated by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and Brunauer–Emmett–Teller surface area. AlN nanocrystals prepared under non-isothermal combustion process were comprised well distributed multi-faceted particles with an average size of 50–200 nm. The chemical reactions in the combustion wave were discussed and a possible thermochemical pathway for the synthesis of AlN nanoparticles was proposed