Inductively coupled nonthermal plasma synthesis of aluminum nanoparticles

Abstract

Metallic nanoparticles of aluminum (Al), a nontoxic and earth-abundant element, are relevant to plasmonic and energetic applications. However, monodisperse Al nanoparticles are difficult to synthesize using all gas-phase approaches, especially in the 10 to 20 nm size range; yet, many applications require particles of this size due to their enhanced properties. Here, an inductive nonthermal plasma reactor fed with aluminum trichloride (AlCl 3 ) and Ar is used to synthesize single-crystal aluminum nanoparticles. The particles can be produced with or without hydrogen. Several reactor conditions such as AlCl 3 vapor concentration, flow rates, and power are found to strongly influence particle properties such as the oxide shell thickness, particle mono-dispersity, and particle size. Significant quantities of Ar relative to AlCl 3 , short residence times of 10 s of ms, and pressures in excess of 4.7 Torr are required to form Al particles with geometric mean sizes of 10-20 nm and geometric standard deviations as low as 1.3. While the Al nanoparticles are covered with 2-4 nm thick oxide shells, the best synthesis conditions yield particle sizes determined by electron microscopy that are comparable to crystallite sizes determined from x-ray diffraction.

A Single-Step Bottom-up Approach for Synthesis of Highly Uniform Mie-Resonant Crystalline Semiconductor Particles at Visible Wavelengths

“…Over the past two decades, nonthermal plasma synthesis has emerged as a competitive technology for the formation of nanocrystals that are difficult or impossible to synthesize with other fabrication techniques. Nanocrystals of covalently bonded group IV elements, − noble and transition metals, − and compound semiconducting materials − are among the vast library of materials successfully synthesized by this all-gas-phase method. Nonthermal plasmas have excellent control over particle size and size distribution owing to the negative charge of the NPs immersed in the plasma, preventing particle agglomeration .…”

Functional Nanomaterials from Waste and Low‐Value Natural Products: A Technological Approach Level

“…[138,139] This set of processes often requires the application of more complex equipment, as compared to the thermochemical methods. [140,141] To date, many types of plasma systems have been designed such as, e.g., DC discharge-based platforms, [142][143][144] microwave systems, [145][146][147] inductively coupled plasma (ICP), [148][149][150] and capacitively coupled plasma (CCP) [151,152] systems, radio-frequency (RF) and magnetrons, [153][154][155][156] and many others. [157][158][159][160] Figure 9.…”

Enhancing the Combustion of Magnesium Nanoparticles via Low-Temperature Plasma-Induced Hydrogenation

“…Nonthermal plasmas can process various materials at near room temperature and low pressures (1–10 Torr). − Free electrons with temperatures in the 1–5 eV range can activate a broad range of chemistries, even while the gas remains close to room temperature, including in the case of the nucleation of nanoparticles. An additional advantage of low-temperature plasmas (LTPs) is the electrostatic stabilization of nanoparticles dispersed within them. , This effect prevents agglomeration, allowing the functionalization of individual particles on-the-fly, as opposed to agglomerates.…”