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Combustion based synthesis of AlN nanoparticles using the "solid nitrogen" promotion reaction was investigated in Al2O3 + 3Mg system in nitrogen atmosphere. A controlled amount of Mg + 0.5NH4Cl mixture as a solid source of nitrogen was blended with the Al2O3 + 3Mg starting system and the synthesis reaction of AlN nanoparticles was conducted using the exothermic heat of the entire reaction system. The resulting AlN nanoparticles were characterized by X-ray diffraction (XRD), Raman and Fourier transform infrared spectroscopy (FTIR), PL spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, and Brunauer-Emmett-Teller surface area techniques. The analysis results confirmed that single phase and crystalline AlN nanoparticles with an average size of 50-500 nm were obtained from the developed approach. Photoluminescence spectra of AlN nanopowders under the excitation of 230-270 nm UV light revealed that AlN emits yellow-red light having a wavelength near to 590 nm. The chemistry of the combustion process is discussed and the basic reactions that led to the formation of AlN are presented. [ABSTRACT FROM AUTHOR]

Abstract: Herein, we present the low-temperature solid-phase combustion synthesis of tantalum carbide (TaC), TaC/tantalum silicide (TaSi2), and TaC/tantalum boride (TaB) nanoparticles by the silicothermic reduction of potassium fluorotantalate (K2TaF7) in the presence of carbon, boron, and polytetrafluoroethylene (PTFE, 1 [1] BJH, Barrett–Joyner–Halenda; HRTEM, high-resolution transmission electron microscopy; MMC, metal matrix composite; PFTE, polyfluorotetraethylene; PTFE; polytetrafluoroethylene; RF, radio frequency; SAED, selected area electron diffraction pattern; T c , combustion temperature; TEM, transmission electron microscopy; U c , combustion velocities; XRD, X-ray diffractometer. (C2F4) n ). The temperature–time profiles of the combustion wave were measured by thermocouples and used to calculate the combustion parameters: temperature and wave velocity. The flame temperature was found to increase with the concentration of PTFE. Using high resolution transmission electron microscopy, a homogeneous distribution of highly crystalline nanoparticles was observed. The thermal–kinetic activation energy, the heat released during each of the individual reactions, and the chemical mechanism of the overall combustion process are discussed with respect to the final products. [Copyright &y& Elsevier]