Comparative study of phase transformation of Al2O3 nanoparticles prepared by chemical precipitation and sol-gel auto combustion methods

Synthesis and characterization of γ-Al2O3 and α-Al2O3 nanoparticles using a facile, inexpensive auto-combustion approach

“…1(b)) appeared at 2θ of 31.10 o , 37.44 o , 39.67 o , 45.96 o , 61.00 o , and 66.97 o could be matched well to the (220), (311), ( 222), (400), (511), and (440) crystal planes, respectively, of cubic γ-Al2O3 (JPCDS card number: 10-0425) [46]. However, the appearance of diffraction peak at 2θ of 33.44 o can be attributed to the transformation of tiny amount of γ-Al2O3 phase into θ-Al2O3 phase [15].…”

“…Furthermore, aluminum oxide is an amphoteric oxide and exists in various polymorphs such as gamma (ɣ-), delta (δ-), theta (ɵ-), rho (ρ-), eta (η-), kappa (ƙ-) and chi (χ)-alumina, in addition to its stable phase (alpha (α)-alumina, corundum) [26]. Among them, alpha-and gamma-alumina have attracted a significant attention of the research groups based on their unique characteristics; therefore, both polymorphs have various applications as mentioned previously [13][14][15][16] plasma synthesis [28], freeze-drying of sulfate solutions [29], the sol-gel method [30,31], laser ablation [32], controlled hydrolysis of metal alkoxide [33], and precipitation [34], precipitation and sol-gel process followed by calcination [35,36], sputtering [37], electrochemical [38], mechanical milling [39], pyrolysis [40], homogenous precipitation followed by calcination [41], and metal organic chemical vapor deposition [42]. However, limitations of these approaches, for both ɣ-and α-alumina nanoparticles, are of great concerns such as long reaction time, uncontrolled particle size, a high-temperature requirement, and use of expensive and toxic organic solvents.…”

“…They showed remarkable applications in catalysis, sensor devices, drug delivery, semiconductor materials, water treatment, and solid oxide fuels [7][8][9][10][11][12]. Among these metal oxides, Al2O3 nanoparticles are one of the nanostructures that have aroused keen interests of the materials science researchers owing to their wide applications such as wear protection, automotive emission control, hydrogenation, metallurgy, refractories, and catalysis in petroleum refining [13][14][15]. These various applications of alumina are due to its interesting characteristics including high catalytic surface activity, good optical activity, high corrosion resistance, and high surface area [16].…”

Sol–Gel Ceramics for SEIRAS and SERS Substrates

“…Behera et al [62] used aluminum nitrate and citrate to produce alumina successfully and were able to estimate the optimal citrate/nitrate ratio for nanoparticles to be formed. Alumina prepared from aluminum nitrate has been used for different applications such as a bioactive composite with hydroxyapatite [63], γ-alumina for the adsorption of lead, cadmium and chromium for environmental applications [64,65], α-alumina nanoparticles obtained using an auto combustion method with aluminum nitrate and urea [66], and yttrium-alumina films doped with different concentrations of europium on silica for its luminescence performance [67].…”

Bio-Mediated Synthesis of Nanomaterials for Electrochemical Sensor Applications

“…Nanoparticles have excellent dissimilar kinds of stuff to that of analogous material in bulk and extended consideration due to their exclusive morphology as well as physiochemical stuff such as tiny size, shape (needles, prisms, disks, leaves, cubes, spheres, sheets, flowers, rods, wires, belts, and tubes), and proper distribution of size [7,8,9]. There are several chemical and physical approaches for the preparation of objects from nano-particles such as chemical auto-combustion [10], sol-gel [11], conventional ceramic process [12], RF-sputtering [13], chemical reduction [14], microemulsion [15], reverse micelles [16], electrochemical reduction [17], Langmuir-Blodgett [18], microwave [19], UV irradiation [20], pyrolysis [21], lithography [22], and laser ablation [23]. However, there is a thoughtful necessity to swap the present methods with an uncontaminated, no-toxicity, and naturally tolerable green chemistry approach [24].…”