Low-Temperature Synthesis of TiC, Mo<sub>2</sub>C, and W<sub>2</sub>C from Modulated Elemental Reactants

Johnson, Christopher D.; Sellinschegg, Heike; Johnson, David C.

doi:10.1021/cm000547c

Cited by 9 publications

(6 citation statements)

References 21 publications

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“…A variety of ZnO nanostructure morphologies, such as nanobelts, [3] nanowires, [4] nanorods, [5] nanotubes, [6] and nanohelices/nanosprings [7] have been synthesized. Metal catalysts, such as gold [1,4,8] and tin [5,9,10] have been employed in the synthesis to align the struc-tures, [1,4,5] confine them in size, [8,9] or to form junctions. [10] Applications of ZnO nanostructures are closely related to their morphology, and most of the ZnO nanostructures reported are dominated by the {0001}, {21 Å 1 Å 0}, and {011 Å 0} facets with solid walls/interiors.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Synthesis of Hierarchical Titanium Carbide from Titania‐Coated Cellulose Paper

Shin¹,

Wang

et al. 2004

Advanced Materials

100

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Transition-metal carbides are key materials with many practical uses in the cutting tool and abrasives industries because of their hardness and chemical stability at high temperatures.[1] In particular, titanium carbide (TiC) is one example of a high-temperature structural material with extreme hardness (28±35 GPa), low density (4.93 g cm ±3 ), high thermal (m.p. 3065 C) and electrical conductivity, and high mechanical stiffness. It has a crystal structure with cubic symmetry (Fm3m) and exhibits non-stoichiometry over a wide range of C:Ti ratios, Ti m C n (n/m = 0.5±1.0) without any change in crystal structure.[2] Uniform fine TiC powders with a homogeneous chemical composition are required for advanced materials applications. In certain cases, Ni, Co, and Fe can be incorporated into the base material as a second phase to improve its fracture toughness. [3] Due to the metal-like properties mentioned above and catalytic properties such as activity and selectivity TiC can be used for anti-wear coatings on cutting tools and as a replacement catalyst for metals.[1]Several methods to synthesize TiC powders have been developed: direct carbonization of Ti metal, [4] the pyrolysis of titanium halide in an alkane-containing gas stream, [5,6] and the carbothermal reduction of TiO 2 with carbon at high temperature (see Eq. 1). [7,8] The first two methods require relatively expensive starting materials and produce materials that are frequently contaminated by a high oxygen content. The third method, which requires higher temperature due to a high kinetic barrier, produces much cleaner TiC. Usually polymers with low molecular weight or small organic molecules such as propane are used as carbon precursors. [9,10] In such cases, relatively low temperature is required to form TiC. However, the use of titanium alkoxide as a TiO 2 precursor makes processing difficult since the chemical is easily hydrolyzed by moisture, even in air. Nano-sized TiO 2 powder has been used to increase the contact area between TiO 2 and carbon, leading to a considerably lower reaction temperature. [11] This report describes the use of cellulose structures as the carbon precursor and aqueous-based Tyzor-LA as the TiO 2 source for the synthesis of TiC nanoparticles by carbothermal reduction in Ar. The hierarchical cellulose structures resident in the filter paper were completely maintained even after treatment at high temperature. Nano-sized TiC powders (10± 50 nm) synthesized at 1500 C showed a minimal oxygen impurity (0.24 wt.-%).Several samples with different weight ratios of filter paper to Tyzor-LA in the range of 3.0±5.0 were prepared to determine the optimum ratio for the formation of stoichiometric TiC with no excess of carbon. A ratio of 4.44 (filter paper/ Tyzor-LA) was found to be optimum. A ratio of 5.0 was found to produce an excess of about 5 wt.-% carbon. Samples with lower ratio (< 4.44) showed an extra rutile phase (TiO 2 ) following reaction at 1500 C in Ar. Figure 1 shows the SEM image of the cellulose paper infiltrated with Tyzor-LA...

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Section: Methodsmentioning

confidence: 99%

“…Usually polymers with low molecular weight or small organic molecules such as propane are used as carbon precursors. [9,10] In such cases, relatively low temperature is required to form TiC. However, the use of titanium alkoxide as a TiO 2 precursor makes processing difficult since the chemical is easily hydrolyzed by moisture, even in air.…”

mentioning

confidence: 99%

Synthesis of Hierarchical Titanium Carbide from Titania‐Coated Cellulose Paper

Shin¹,

Wang

et al. 2004

Advanced Materials

100

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“…Traditionally, the micron size Mo 2 C is produced by direct carburization of molybdenum and molybdenum oxide powders at higher temperatures 9 . However, for the synthesis of nano Mo 2 C powder different procedures are adopted 10 – 17 .…”

Section: Introductionmentioning

confidence: 99%

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

Mir

Sharma

Pandey

2017

Sci Rep

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Carbon coated nano molybdenum carbide (Mo2C) has been synthesized at 800 °C through single step reduction route using molybdenum trioxide (MoO3) as a precursor, polypropylene (P.P) as a carbon source and magnesium (Mg) as a catalyst in an autoclave. The synthesized samples were characterized by X-ray diffraction (XRD), thermal analysis techniques (TG/DTA/DTG), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Williamson- Hall (W-H) analysis has been done to estimate various parameters like strain, stress and strain energy density. Multi-stage kinetic analysis of the product phase has been studied to establish the nature of the thermal decomposition. Coats-Redfern method applied to determine the mechanism involved in the decomposition of the product phase shows that initial and final stage follow F1 mechanism whereas middle stage follow F3 mechanism. The activation energy (E a) and pre-exponential factor (A) has also been determined. The morphological studies show that the particles have partially spherical/faceted shape, with carbon coated having wide particle size distribution. The surface chemistry and surface area analysis were studied by X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmet-Teller (BET), respectively. The formation mechanism of carbon coated Mo2C nano particles has been predicted based on the XRD, TG/DTA & DTG and microstructural results.

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“…Johnson et al synthesized dense thin films of TiC, Mo 2 C, and W 2 C by employing direct electron beam evaporation of carbon and metal sources resulting in the deposition of alternating carbon-metal layers 2-40 A ˚thick; however, the deposited films required annealing at elevated temperatures (350-600 °C) in order to form carbide. 22 Alternatively, reactive ballistic deposition (RBD) can be utilized to deposit TiC films while providing control of the film's morphology, surface area, and porous architecture. [23][24][25] In ballistic or "hit and stick" deposition schemes, high surface area, porous films are prepared by deposition at oblique angles.…”

Section: (I) Introductionmentioning

confidence: 99%

Low Temperature Synthesis and Characterization of Nanocrystalline Titanium Carbide with Tunable Porous Architectures

Flaherty¹,

May²,

Berglund³

et al. 2009

Chem. Mater.

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High surface area, porous titanium carbide films have been synthesized at room temperature via reactive ballistic deposition (RBD). X-ray diffraction and X-ray photoelectron spectroscopy show that evaporative deposition of titanium in an ethylene ambient environment allows for low temperature (35 °C) synthesis of nanocrystalline titanium carbide, a material which typically requires high processing temperatures to produce. Angle-dependent RBD allows for the controlled tuning of TiC nanostructure and porosity where changing the deposition angle from near normal incidence (13°) to more glancing angles (50−85°) changes the film morphology from relatively nonporous, dense TiC to a continuous, reticulated TiC and finally to discrete, nanocolumnar TiC. The influence of the deposition angle on TiC optical constants, porosity, specific surface area, and the pore size distribution has been investigated using hybrid quartz crystal microbalance and ellipsometric porosimetry. Notably, TiC films deposited at 35 °C at an angle of 70° have a specific surface area of 710 m2·g−1 and a mean Kelvin radius of 1.8 nm, making them attractive materials for application in catalysis, energy conversion, and storage.

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Low-Temperature Synthesis of TiC, Mo₂C, and W₂C from Modulated Elemental Reactants

Cited by 9 publications

References 21 publications

Synthesis of Hierarchical Titanium Carbide from Titania‐Coated Cellulose Paper

Synthesis of Hierarchical Titanium Carbide from Titania‐Coated Cellulose Paper

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

Low Temperature Synthesis and Characterization of Nanocrystalline Titanium Carbide with Tunable Porous Architectures

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Low-Temperature Synthesis of TiC, Mo2C, and W2C from Modulated Elemental Reactants

Cited by 9 publications

References 21 publications

Synthesis of Hierarchical Titanium Carbide from Titania‐Coated Cellulose Paper

Synthesis of Hierarchical Titanium Carbide from Titania‐Coated Cellulose Paper

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

Low Temperature Synthesis and Characterization of Nanocrystalline Titanium Carbide with Tunable Porous Architectures

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Low-Temperature Synthesis of TiC, Mo₂C, and W₂C from Modulated Elemental Reactants