Morphology Control of Tantalum Carbide Nanoparticles through Dopant Additions

Abstract

The control of powder morphology in metals and ceramics is of critical importance in applications such as catalysis and chemical sensing whereby specific crystal facets better facilitate chemical reactions. In response to this challenge, we present a combined experimental and computational approach that examines the principles behind dopant-induced crystallographic faceting in nanoparticles. We base our study on nanoparticles of tantalum carbide doped with nickel, iron, cobalt, niobium, and titanium and observe a very significant transition from round/irregular particle shapes to cubes and cuboctahedrons upon the addition of transition metal dopants. The presence of the dopants, which segregate toward the surface of the particles, results in atomic orbital hybridization, causing a significant decrease of up to 0.13 eV•Å −2 in the surface energy of the (100) facets, thus providing the driving force for the formation of nanocubes with exposed (100) surfaces. These principles can be generalized to other ceramics and serve as guidance for the optimized control of shape in powders. For example, if one seeks to produce highly faceted V-, Hf-, or Zr-carbide nanoparticles, doping strategies reported here can be applied. Other elements may also be effective in changing the growth habits of crystals based on surface segregation and dopant−host atomic orbital hybridization.

Phase and Morphology Control of Hexagonal MoO3 Crystals via Na+ Interactions: A Raman Spectroscopy Study

“…The presence of needle-like structures and incomplete elongated crystals shows the presence of α-MoO 3 , which agrees with the XRD and Raman results. Thus, from SEM, it is seen that powder morphologies − can be controlled by varying the phases in this material. The darker rectangular structures from samples AP10 and AP15 were analyzed by EDS and are depicted in Figure .…”

Scientific Breakdown of a Ferromagnetic Nanofluid in Hemodynamics: Enhanced Therapeutic Approach

“…It is observed that the temperature is enhanced with enhancing for other values of the parameters under consideration. Inversely, it is noticed from Figs 13. and 14 that Φ !…”

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Phase Transitions and Oxidation Behavior During Oxyacetylene Torch Testing of TaC–HfC Solid Solutions

“…[ 16–19 ] In particular, transition metal carbides such as tantalum carbide (TaC) and hafnium carbide (HfC) have gained significant interest because they possess the highest melting temperatures, above 4000 K, among transition metal carbides. [ 20 ] TaC and HfC crystallize in the cubic rock‐salt () structure and exhibit mixed covalent, ionic, and metallic bonding, [ 21 ] which gives rise to high thermal conductivity (≈55.8 W m −1 ⋅ K), [ 22 ] significant flexural strength (≈500 MPa), [ 23,24 ] and relatively high hardness (≈15 GPa). [ 25,26 ] These carbides can also form a passive oxide surface layer that provides some oxidation resistance.…”