Morphology-controlled synthesis of quasi-aligned AIN nanowhiskers by combustion method: Effect of NH4Cl additive (original) (raw)
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AlN nanoparticles were synthesized by carbothermal reduction method using a combustion synthesis precursor derived from aluminum nitrate, glucose, and urea mixed solution. Effects of urea on the combustion temperature of solutions, the particle size and morphology of precursors, the intermediate formed -alumina, and the synthesized AlN were studied in detail. The results indicated that the homogeneous mixture of amorphous (Al2O3 + C) precursor might be prepared by selecting an optimum molar ratio of urea to aluminum nitrate (U/Al) in solution by combustion synthesis method. Furthermore, a regular variation in the particle size and morphology of precursors had been observed with increasing (U/Al). The nitridation products, synthesized at 1500 ◦C, retained the characteristics of -alumina in the precursors. The nitridation products, prepared with (U/Al = 0.5–2), comprised of well-distributed spherical particles of AlN with the average size ranging from 30 to 80 nm. Moreover, the nitridation reactivity of products with (U/Al = 0.5–2) had been found at 99%, which was significantly higher than that of the nitridation products prepared with (U/Al = 0.3, 2.5, 3) and without urea.
Fuel effects on properties of alumina nanoparticles synthesized by combustion technique
Indian Journal of Pure & Applied Physics, 2016
Alumina nanopowders have been produced by solution combustion synthesis using aluminum nitrate as oxidizer and urea (U), ammonium acetate (AA) and ammonium nitrate (AN) as fuels. The fuel effects on properties of products have been studied. Enthalpy and adiabatic flame temperature are calculated theoretically for each fuel based on thermodynamic concept to determine its exothermicity. Thermogravimetric (TG) analysis has also been carried out to determine the thermal properties of the metal nitrate and fuels. The prepared samples have been characterized by X-ray diffraction (XRD), N 2 adsorption (BET) and scanning electron microscopy (SEM). The results show that by reducing the exothermicity of reaction, alumina nanopowders with smaller crystallite size, finer agglomerate and higher specific surface area are produced.
Solution Combustion Preparation Of Nano-Al2O3: Synthesis and Characterization
The aluminum oxide materials are widely used in ceramics, refractories and abrasives due to their hardness, chemical inertness, high melting point, non-volatility and resistance to oxidation and corrosion. The paper describes work done on synthesis of α-alumina by using the simple, non-expensive solution combustion method using glycine as fuel.Aluminum oxide (Al2O3) nanoparticles were synthesized by aluminum nitrate 9-hydrate as precursor and glycine as fuel. The samples were characterized by high resolution transmission electron microscopy (HRTEM), field effect scanning electron microscopy (FESEM), X-ray diffraction (XRD) and electron dispersive spectroscopy (EDS). As there are many forms of transition aluminas produced during this process, x-ray diffraction (XRD) technique was used to identify α-alumina. The diameter of sphere-like as-prepared nanoparticles was about 10 nm as estimated by XRD technique and direct HRTEM observation. The surface morphological studies from SEM depicted the size of alumina decreases with increasing annealing temperature. Absorbance peak of UV-Vis spectrum showed the small bandgap energy of 2.65 ev and the bandgap energy increased with increasing annealing temperature because of reducing the size.