Electrical resistivity of silicon carbide ceramics sintered with 1 wt% aluminum nitride and rare earth oxide

High temperature strength of silicon carbide sintered with 1 wt.% aluminum nitride and lutetium oxide

“…This result suggested that 1 wt.% AlN-Lu 2 O 3 additives are sufficient to densifiy SiC to a theoretical density greater than 98% by conventional hot-pressing at 2050 • C for 6 h under an applied pressure of 40 MPa in flowing nitrogen. In a previous study, 29 the relative density of SiC sintered with submicronsize SiC, 5 wt.% in situ-synthesized nano-sized SiC, and 1 wt.% AlN-Lu 2 O 3 additives by conventional hot-pressing at 2050 • C for 12 h under an applied pressure of 20 MPa in flowing nitrogen was 97.8%. Although the sintering time was shortened from 12 h to 6 h and in situ-synthesized nano-sized SiC was not added, the enhanced densification achieved was caused by an increase in applied pressure from 20 MPa to 40 MPa.…”

“…It is well documented that the ␤ → ␣ phase transformation of SiC generally results in faceting of the SiC grains. 30,31 An HRTEM micrograph of a triple point is shown in Fig. 3.…”

Enhanced electrical conductivity of silicon carbide ceramics by addition of graphene nanoplatelets

“…High conductivities are also obtained with additive systems based on AlN (e.g. 2 × 10 3 S m −1 for AlN-RE 2 O 3 , RE = Y, Er [8,9]). Comparatively lower σ values (10 −9 -10 −1 S m −1 ) were reported when employing only oxide additives such as Y 2 O 3 and Al 2 O 3 [6,[10][11][12], depending on the dopant concentration and the nature, location and thickness of grain boundaries.…”

“…From the electrical conduction viewpoint, SiC is a semiconductor with fairly large band gap energies ranging from ∼2.4 to 3.4 eV, depending on the structural polytype [4,5], thus exhibiting low electrical conductivity (σ) (close to 10 −13 S m −1 [6]). However, SiC-based ceramics can be tailored to display very diverse σ values within a range from 10 −9 to 10 5 S m −1 [6][7][8][9][10][11][12][13][14], depending on the type of doping, often resulting from sintering additives. In this sense, the case of sintering additives containing nitrogen (N) is especially significant, since N atoms can be incorporated into the SiC lattice substituting for carbon (C) during sintering [15], creating a donor level within the bandgap.…”

Electrical and thermal properties of silicon carbide–boron nitride composites prepared without sintering additives

“…During sintering at 2200 • C in argon, the ␤ → ␣ phase transformation took place in the composites and the resulting composites consisted of ␣-SiC and h-BN if the phase transformation was completed or ␣-SiC, ␤-SiC, and h-BN if the phase transformation was not completed. It was reported that the occurrence of the ␤ → ␣ phase transformation in SiC during sintering significantly increased its electrical resistivity [42]. A maximal electrical resistivity of 1.0 × 10 12 cm was reported in SiC-10 wt% BN composites sintered with 0.6 wt% B 4 C and 1.5 wt% C [15].…”