High‐Pressure Sintering of Rhombohedral Cr₂S₃ Using Titanium–Zirconium–Molybdenum Tools

Abstract

The influence of sintering parameters on the physical properties and the chemical structure of rhombohedral Cr 2 S 3 (rh-Cr 2 S 3 ) is investigated using high pressures and high temperatures. The densification of the powder is performed by applying the high-pressure field-assisted sintering technique/spark plasma sintering. Using a titanium-zirconium-molybdenum (TZM) alloy as sintering tool, it is possible to increase the magnitude of the applied pressure to several hundred MPa at temperatures as high as 1223 K. A relative density of up to 99.9% is achieved at a sintering temperature of 1223 K and a pressure of 395 MPa. The presence of phase-pure rh-Cr 2 S 3 is proven by X-ray diffraction analysis and transmission electron microscopy. The Seebeck coefficients of the self-doped samples change drastically with the sintering temperatures ranging between À650 and À350 μV K À1 . The densities and the thermal conductivities of the sintered samples increase with increasing sintering temperatures. The electrical conductivity is largely increased compared with the thermal conductivity potentially due to the current-assisted high-pressure sintering.

High Surface Area of Polyhedral Chromia and Hexagonal Chromium Sulfide by the Thermolysis of Cyclohexylammonium Hexaisothiocyanatochromate(III) Sesquihydrate

“…[58][59][60][61][62][63][64][65][66][67][68] On the other hand, the industrial applications of Cr 2 S 3 have been realized in the manufacture of catalysts, supercapacitors, and energy storage devices. [69][70][71][72][73] between the theoretical and experimental results was within the acceptable error range, confirming the molecular formula of C 24 H 45 N 9 S 6 O 1.5 Cr for our synthesized hybrid organic-inorganic salt.…”

“…[65] Figure 7 205), (027), (008), and (224), respectively, for the trigonal phase. [72] In addition, the rhombohedral phase was detected with peaks at 2 theta 30, 34, and 58°assigned to the (110), (113), and (303) planes, respectively. [92] Scherrer's equation was applied to calculate the crystallite size.…”

“…The values for Cr 2 O 3 were a = b = 4.940 and c = 13.590 Å, in agreement with values reported in literature, [94] while for Cr 2 S 3 , the values were a = b = 6.17 and c = 11.520 Å, and the obtained data were greatly similar to previously reported data. [72] In accordance with the Williamson-Hall method, [95] strain (ε) and crystallite size (D) have substantial contribution to the diffraction lines broadening (equation 3) where they are only considered to reflect the peak width due to their to 2θ. [96,97] In the uniform deformation model UDM (equation 4) of Williamson-Hall approach, it is assumed that crystals are isotropic [98] and subsequently their properties are independent of the crystallographic direction along which the measurement is performed.…”

Field-Assisted Sintering/Spark Plasma Sintering of Gadolinium-Doped Ceria with Controlled Re-Oxidation for Crack Prevention

“…For instance, replacing graphite tool by a tool manufactured from titanium-zirconium-molybdenum (TZM) alloy enables significant increase of applied pressure [ 30 ]. In particular, Groeneveld et al reported sintering of Cr 2 S 3 powder in a TZM tool at a pressure of 395 MPa and at a temperature of 950 °C [ 31 ]. However, the use of such a tool is apparently limited by a maximum temperature of around 1200 °C, at which recrystallization of TZM starts causing the abrupt decrease of mechanical strength [ 32 ].…”

Thermal Stability of Nanocrystalline NiS2 as High Specific Capacity Thermal Battery Cathode Material

“…At present, the cathode material is the main limiting factor in improving the discharge performance of thermal batteries. [9] Due to the excellent electrical, optical, and magnetic properties, transition metal sulfides have been intensively studied [10][11][12][13][14][15] and extensively applied in different areas. [16][17][18][19][20][21][22] NiS 2 , an important transition metal sulfide, has been considered to be an attractive candidate for the cathode material of thermal batteries due to its excellent intrinsic performance and low cost.…”