A method of making Si.sub.3N.sub.4 nanotubes and nanorods comprising adding agricultural husk material powder to a container, wherein the container is a covered boron nitride crucible, creating an inert atmosphere of nitrogen inside the container, applying heat, heating the agricultural husk material, and reacting the agricultural husk material and forming silicon nitride, wherein the silicon nitride is nanotubes and nanorods.

Si.sub.3N.sub.4 nanotubes and nanorods wherein the nanotubes and nanorods of silicon nitride are pure -Si.sub.3N.sub.4 formed by carbothermal reduction of SiO.sub.2 from reacting agricultural husk material in heat and forming the silicon nitride nanotubes and nanorods.

A method of producing ceramic wafer includes a forming step and processing step. The processing step includes forming positioning notch or positioning, flat edge and edge profile, which avoids the ceramic wafers to have processing defect during cutting, grinding, and polishing, for increasing yield. The ceramic particles for producing ceramic wafer include nitride ceramic powder, oxide ceramic powder, and nitride ceramic powder. The ceramic wafer has low dielectric constant, insulation, and excellent heat dissipation, which can be applied for the need of semiconductor process, producing electric product and semiconductor equipment.

Methods, systems, and components suitable for carbothermal reduction processes are disclosed. Exemplary systems include a reactor, such as hybrid solarthermal-electric reactor, a solar thermal reactor, an electric reactor, or a reactor heated by gas combustion, a pellet source, a gas reactant source, and a vacuum source. The reactor can operate as a moving bed or pseudo moving bed reactor.

Si.sub.3N.sub.4 nanotubes and nanorods wherein the nanotubes and nanorods of silicon nitride are pure -Si.sub.3N.sub.4 formed by carbothermal reduction of SiO.sub.2 from reacting agricultural husk material in heat and forming the silicon nitride nanotubes and nanorods.

A method of making Si.sub.3N.sub.4 nanotubes and nanorods comprising adding agricultural husk material powder to a container, wherein the container is a covered boron nitride crucible, creating an inert atmosphere of nitrogen inside the container, applying heat, heating the agricultural husk material, and reacting the agricultural husk material and forming silicon nitride, wherein the silicon nitride is nanotubes and nanorods.

A method of producing ceramic wafer includes a forming step and processing step. The processing step includes forming positioning notch or positioning, flat edge and edge profile, which avoids the ceramic wafers to have processing defect during cutting, grinding, and polishing, for increasing yield. The ceramic particles for producing ceramic wafer include nitride ceramic powder, oxide ceramic powder, and nitride ceramic powder. The ceramic wafer has low dielectric constant, insulation, and excellent heat dissipation, which can be applied for the need of semiconductor process, producing electric product and semiconductor equipment.

A silicon nitride powder to be used in a slurry for forming a mold release layer of a polycrystalline silicon casting mold, wherein the specific surface area thereof is 5-50 m.sup.2/g, the proportion of amorphous silicon nitride is 1.0-25.0 mass %, and the oxygen content is 0.6-2.5 mass %. A silicon nitride powder slurry for use in mold release material and capable of forming, on a polycrystalline silicon casting mold, a mold release layer which exhibits favorable mold release properties and exhibits favorable adhesion to the casting mold after casting the polycrystalline silicon ingot, and a method for producing the same. A silicon nitride powder for mold release material, a silicon nitride powder for a slurry use for obtaining the silicon nitride powder slurry for use in the mold release material, and a method for producing the same. A polycrystalline silicon casting mold which exhibits favorable mold release properties of a polycrystalline silicon ingot; and method for producing the same.