An optical device includes a vanadium compensated, high resistivity, SiC single crystal of 6H or 4H polytype, for transmitting light having a wavelength in a range of from 420 nm to 4.5 μm. The device may include a window, lens, prism, or waveguide. A system includes a source for generating light having a wavelength in a range of from 420 nm to 4.5 μm, and a device for receiving and transmitting the light, where the device includes a vanadium compensated, high resistivity, SiC single crystal of 6H or 4H polytype. The disclosure also relates to crystals and methods for optical applications, including an aluminum doped SiC crystal having residual nitrogen and boron impurities, where the aluminum concentration is greater than the combined concentrations of nitrogen and boron, and where an optical absorption coefficient is less than about 0.4 cm.sup.−1 at a wavelength between about 400 nm to about 800 nm.

In an embodiment, a magneto-dielectric material comprises a polymer matrix; a plurality of hexaferrite microfibers; wherein the magneto-dielectric material has a permeability of 2.5 to 7, or 2.5 to 5 in an x-direction parallel to a broad surface of the magneto-dielectric material and a magnetic loss tangent of less than or equal to 0.03; as determined at 1 GHz, or 1 to 2 GHz.

In a diamond polycrystal, a value of a ratio (a/a) of a to a is less than or equal to 0.99 in a Knoop hardness test performed under a condition defined in JIS Z 2251:2009, where the a represents a length of a longer diagonal line of a first Knoop indentation formed in a surface of the diamond polycrystal when a Knoop indenter with a test load of 4.9 N is pressed onto the surface of the diamond polycrystal, and the a represents a length of a longer diagonal line of a second Knoop indentation remaining in the surface of the diamond polycrystal after releasing the test load.

A cBN sintered material cutting tool includes a cutting tool body that is made of a sintered material including cubic boron nitride particles and a binder phase, in which: an average particle size of the cBN particles is 0.5 m or less and a content ratio of the cBN particles in the sintered material is 35 vol % to 80 vol %; and the binder phase includes 1.0 vol % to 20 vol % of an Al compound, an average particle size of the Al compound present in the binder phase is 300 nm or less, and a value of a ratio (a value of S.sub.N/S.sub.O; area ratio) of a content S.sub.N of nitrogen (N) included in the Al compound to a content S.sub.O of oxygen (O) included in the Al compound is 1.1 to 5.

Provided is a SiC sintered body which contains nitrogen atoms, wherein a ratio R.sub.max/R.sub.ave of a maximum volume resistivity R.sub.max of the sintered body to an average volume resistivity R.sub.ave of the sintered body is 1.5 or lower; a ratio R.sub.min/R.sub.ave of a minimum volume resistivity R.sub.min of the sintered body to the average volume resistivity R.sub.ave is 0.7 or higher; and a relative density of the sintered body is 98% or higher.

Provided is a SiC sintered body which contains nitrogen atoms, wherein a ratio R.sub.max/R.sub.ave of a maximum volume resistivity R.sub.max of the sintered body to an average volume resistivity R.sub.ave of the sintered body is 1.5 or lower; a ratio R.sub.min/R.sub.ave of a minimum volume resistivity R.sub.min of the sintered body to the average volume resistivity R.sub.ave is 0.7 or higher; and a relative density of the sintered body is 98% or higher.

Provided are a polycrystalline SiC compact capable of achieving uniform plasma etching when used as electrodes and a method for manufacturing the same. A polycrystalline SiC compact has a major surface in which Wa (0 to 10 mm) is 0.00 to 0.05 m or less, Wa (10 to 20 mm) is 0.13 m or less, and Wa (20 to 30 mm) is 0.20 m or less.

A semiconductor device comprising: a semiconductor component; a diamond heat spreader; and a metal bond, wherein the semiconductor component is bonded to the diamond heat spreader via the metal bond, wherein the metal bond comprises a layer of chromium bonded to the diamond heat spreader and a further metal layer disposed between the layer of chromium and the semiconductor component, and wherein the semiconductor component is configured to operate at an areal power density of at least 1 kW/cm.sup.2 and/or a linear power density of at least 1 W/mm.

Antiballistic armour plate includes a ceramic body including a hard material, provided, on its inner face, with a back energy-dissipating coating. The ceramic body is monolithic. The constituent material of the ceramic body includes grains of ceramic material having a Vickers hardness that is higher than 15 GPa, and a matrix binding the grains, the matrix including a silicon nitride phase and/or a silicon oxynitride phase, the matrix representing between 5 and 40% by weight of the constituent material of the ceramic body. The maximum equivalent diameter of the grains of ceramic material is smaller than or equal to 800 micrometres. The constituent material of the ceramic body has an open porosity that is higher than 5% and lower than 14%. The metallic silicon content in the material, expressed per mm of thickness of the body, is lower than 0.5% by weight.

The present invention relates to a porous alpha-SiC-containing shaped body with a gas-permeable, open-pored pore structure comprising platelet-shaped crystallites which are connected to form an interconnected, continuous skeletal structure, wherein the skeletal structure consists of more than 80 wt.-% alpha-SiC, relative to the total weight of SiC, a process for producing same and its use as a filter component.