In this paper, a new method for the synthesis of aluminum oxide (Al₂O₃) nanowires using decagonal Al₆₅Cu₁₅Co₂₀ quasicrystals as a catalyst is presented. The method is based on the decomposition of water at high temperatures and the subsequent peritectic reaction between aluminum released from the quasicrystal and oxygen formed during the decomposition of water.
Aluminum oxide (Al₂O₃) nanowires have attracted considerable attention due to their unique properties, such as high thermal and chemical stability, mechanical strength, and dielectric properties. They are widely used in various fields, including catalysis, electronics, sensors, and nanocomposite materials. Existing methods for synthesizing Al₂O₃ nanowires, such as sol-gel, chemical vapor deposition, and laser ablation, often require complex equipment, high temperatures, and expensive precursors. Therefore, the development of new, cost-effective, and environmentally friendly methods for synthesizing Al₂O₃ nanowires is an urgent task.
In this paper, we report the results of the synthesis of Al2O3 nanowires obtained by chemical interaction of aluminum and water vapor at 1050 °C. Our method is based on two key aspects. First, we found that the Al65Cu15Co20 alloy undergoes the following reaction at room temperature: 2Al (s) + 3H2O (g) → Al2O3 (s) + H2 (g). During this reaction, the released hydrogen causes fragmentation of the material, leading to the formation of small particles. Second, upon heating, the quasi-crystalline structure of Al65Cu15Co20 is transformed into a liquid + cubic Al (Cu, Co) phase through a peritectic transformation at 1050 °C. This aluminum-rich liquid reacts with water vapor to form Al2O3.
X-ray diffraction (XRD) confirms that the obtained nanowires have a hexagonal structure, and infrared spectroscopy (IR) further confirms the presence of the α-Al2O3 phase in the final products. Transmission electron microscopy (TEM) studies revealed the presence of nanoparticles at the ends of the nanowires, indicating the VLS growth mechanism. Composition analysis using energy dispersive spectroscopy (EDS) shows that the particles at the ends of the nanowires are predominantly composed of alloying elements Co and Cu with a small amount of Al. Microscopic observations showed that the diameter of the nanowires varies from 20 to 70 nm, with an average value of 37 nm, and their length reaches several micrometers.
Decagonal quasicrystals of Al₆₅Cu₁₅Co₂₀ obtained by arc melting with subsequent quenching were used as a catalyst. The nanowires were synthesized in a tubular furnace at a temperature of 900-1100 °C in an argon atmosphere saturated with water vapor. The quasicrystals were placed in a ceramic crucible, which was installed in the center of the furnace. After reaching the specified temperature, argon passed through distilled water was fed into the furnace. The synthesis time varied from 30 minutes to 2 hours. The obtained samples were analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD).
Author: JO Téllez-Vázquez a, C. Patiño-Carachure b, G. Rosas a
Institute: Metallurgy and Materials Research Institute, UMSNH, Building U, University Campus, CP 58060 Morelia, Michoacan, Mexico, Faculty of Engineering, Autonomous University del Carmen, Campus III, Avenida Central, Esq. Con Fract. Mundo Maya, CP 24115 Ciudad del Carmen, Campeche, Mexico