Polytypes of Plate-like Grains in Pressureless-sintered SiC

Microstructure and mechanical properties of pressureless sintered alumina-silver composites

The silver toughened alumina ceramics, which were fabricated via a conventional ceramic processing route using commercially available alumina and silver oxide powders as the starting materials, exhibit a higher fracture toughness (6 to 9 MPamo.5) than the monolithic alumina ceramic ( 2.5 to 3.0 MPamo.5). The weak interfacial bonding between the silver inclusions and the alumina matrix is charac...

The effect of powder type and CaO additive on properties of sintered SiC by pressureless sintering in additive system of Al2O3-Y2O3-CaO

In this study, the effect of two types of SiC powders consist of SiC-1 (β-SiC) and SiC-2 (β-SiC+α-SiC) and also different values of CaO additive consist of 0, 0.4 and 0.8 weight percent on sintering behavior of sintered SiC with pressureless technique in Al2O3-Y2O3-CaO additive system  was investigated. In all specimens, Al2O3:Y2O3 molar ratio was equal to 3:2 and all amounts of additive were e...

Infrared spectra of meteoritic SiC grains

We present here the first infrared spectra of meteoritic SiC grains. The mid-infrared transmission spectra of meteoritic SiC grains isolated from the Murchison meteorite were measured in the wavelength range 2.5–16.5 μm, in order to make available the optical properties of presolar SiC grains. These grains are most likely stellar condensates with an origin predominately in carbon stars. Measure...

PRESOLAR SiC GRAINS OF TYPE C

Optical Investigations of stacking faults in 4H-SiC epitaxial layers: comparison of 3C and 8H polytypes

We present an analysis of the electronic structure of in-grown 3C and 8H stacking faults (SFs) in a 4H-SiC matrix. First the concept of low temperature photoluminescence optical signature of SFs is discussed. Then, the results of type-II quantum well (QW) model calculations are displayed, taking into account the effect of valence band offset, internal polarization field and non homogeneity of t...