Statistical Experimental Design Approach for the Solvothermal Synthesis of Nanostructured Tantalum Carbide Powders

Abstract

We report on the preparation of tantalum carbide nanopowders via a modified solvothermal synthesis route by using experimental design principles. The reaction proceeds by self‐propagating behavior in a molten metal after thermal‐ignition of tantalum chloride, carbon, and a metal reductant. A 4 × 4 × 3 experimental design matrix was performed, without replication, to observe the effects of carbon stoichiometry, reductant stoichiometry, and reductant type on process response variables concerning phase purity, compound stoichiometry, crystallite size, particle size, and surface characteristics. Statistical verifications of the observed effects were performed using a 2 × 2 × 2 experimental design matrix with replication. Eleven conditions resulted in phase‐pure tantalum carbide, with an additional four nonoxide conditions with low secondary‐phase content. The stoichiometry (x in TaCx) ranged from 0.92 to 0.96, the average crystallite size ranged from 24 to 68 nm, the specific surface area ranged from 25 to 66 m2/g, and the average particle size ranged from 93 to 123 nm, indicating a low level of agglomeration.

Correlation between Particle Size and Raman Vibrations in WO3 Powders

“…In this study, we present a correlation between powder particle size, determined from dynamic light scattering, − and the bonding characteristics of tungsten oxide powders, showing that the W–O–W/WO integrated intensity ratio is directly related to the particle size of our free-flowing powders and not just to the grain size of WO 3 films, as has previously been shown. This correlation can serve as a complementary technique to gauge particle size as well as crystallinity in WO 3 powders.…”

Thermal and structural studies of carbon coated Mo2C synthesized via in-situ single step reduction-carburization

“…In stage 1, the observed mass loss of ~1% (Fig. 2a ) occurred due to the removal of moisture and other volatile species adsorbed on the sample surface 39 . In stage 2, the mass gain observed is ~2.3% at ~326 °C (Fig.…”

Distribution of Eu2+ and Eu3+ Ions in Hydroxyapatite: A Cathodoluminescence and Raman Study

“…As-synthesized and calcined samples were characterized with a Bruker D2 Phaser X-ray diffractometer, using CuKα radiation and a step size of 0.01° over the 2θ range of 20 to 80 degrees. Raman spectroscopy was completed on a Horiba Jobin-Yvon LabRam Hr800 confocal microscope with a 630 nm laser at 300 K. Particle size distributions were determined using a Microtrac Nanotrac ULTRA dynamic light scattering (DLS) system, − dispersing approximately 0.48 g of powder in 25 mL of ethanol, stirring for 15 min and ultrasonicating for 5 min. Energy-dispersive spectroscopy was used to determine elemental composition using an X-Max Oxford-Instruments system with a detector size of 20 mm 2 .…”