The present invention relates to a process for the synthesis of a composite material comprising steps of: (a) reacting gaseous magnesium (Mg) and silica (SiO.sub.2) in an inert atmosphere; (b) washing the product obtained in step (a) in an acidic medium; and (c) reacting further gaseous magnesium (Mg) with the silica (SiO.sub.2) and silicon (Si) product obtained in step (b). The process of the invention allows Mg.sub.2Si/MgO nanocomposites to be prepared without too many separate steps, and wherein the MgO phase is homogeneously dispersed within the Mg.sub.2Si matrix. The nanocomposites obtained may for example find practical application as thermoelectric materials in thermoelectric generators.

The present invention relates to a process for the synthesis of a composite material comprising steps of: (a) reacting gaseous magnesium (Mg) and silica (SiO.sub.2) in an inert atmosphere; (b) washing the product obtained in step (a) in an acidic medium; and (c) reacting further gaseous magnesium (Mg) with the silica (SiO.sub.2) and silicon (Si) product obtained in step (b). The process of the invention allows Mg.sub.2Si/MgO nanocomposites to be prepared without too many separate steps, and wherein the MgO phase is homogeneously dispersed within the Mg.sub.2Si matrix. The nanocomposites obtained may for example find practical application as thermoelectric materials in thermoelectric generators.

Silicon materials suitable for use as an anode material and associated method of production are disclosed herein. In one embodiment, a silicon material includes crystalline silicon in a matrix and macro-scale pores distributed in the matrix of the crystalline silicon. The macro-scale pores can have a size greater than 100 nanometers, and surfaces of crystalline silicon in the macro-scale pores are coated with carbon.

Silicon materials suitable for use as an anode material and associated method of production are disclosed herein. In one embodiment, a silicon material includes crystalline silicon in a matrix and macro-scale pores distributed in the matrix of the crystalline silicon. The macro-scale pores can have a size greater than 100 nanometers, and surfaces of crystalline silicon in the macro-scale pores are coated with carbon.

It is difficult for a Cr—Si-based sintered body composed of chromium silicide (CrSi.sub.2) and silicon (Si) to have high strength.

Provided is a Cr—Si-based sintered body including Cr (chromium) and silicon (Si), in which the crystal structure attributed by X-ray diffraction is composed of chromium silicide (CrSi.sub.2) and silicon (Si), a CrSi.sub.2 phase is present at 60 wt % or more in a bulk, a density of the sintered body is 95% or more, and an average grain size of the CrSi.sub.2 phase is 60 μm or less.

A thermoelectric conversion material made of a sintered body containing a magnesium silicide as a major component includes: a magnesium silicide phase; and a magnesium oxide layer formed on a surface layer of the magnesium silicide phase, in which an aluminum concentrated layer having an Al concentration higher than an aluminum concentration in an inside of the magnesium silicide phase is formed between the magnesium oxide layer and the magnesium silicide phase, and the aluminum concentrated layer has a metallic aluminum phase including aluminum or an aluminum alloy.

A method is useful for preparing alkylalkoxysilanes, such as alkylalkoxysilanes, particularly dimethyldimethoxysilane. The method includes heating at a temperature of 150° C. to 400° C., ingredients including an alkyl ether and carbon dioxide, and a source of silicon and catalyst. The carbon dioxide eliminates the need to add halogenated compounds during the method.

A semiconductor substrate contains a clathrate compound of the following General Formula (I). The semiconductor substrate includes a variable-composition layer which includes a pn junction and where composition of the clathrate compound varies along a thickness direction. A rate of change in y in the thickness direction of at least a portion of the variable-composition layer is 1×10.sup.−4/μm or more.
A.sub.xB.sub.yC.sub.46-y   (I) In General Formula (I), A represents at least one element selected from the group consisting of Ba, Na, Sr, and K, B represents at least one element selected from the group consisting of Au, Ag, Cu, Ni, and Al, and C represents at least one element selected from the group consisting of Si, Ge, and Sn, x is 7 to 9, and y is 3.5 to 6 or 11 to 17.

Methods of making a negative electrode material for an electrochemical cell that cycles lithium ions is provided. The method may include centrifugally distributing a molten precursor comprising silicon, oxygen, and lithium by contacting the molten precursor with a rotating surface in a centrifugal atomizing reactor. The molten precursor is formed by combining lithium, silicon, and oxygen. For example, the precursor may be formed from a mixture comprising silicon dioxide (SiO.sub.2), lithium oxide (Li.sub.2O), and silicon (Si). The method may further include solidifying the molten precursor to form a plurality of substantially round solid electroactive particles comprising a mixture of lithium silicide (Li.sub.ySi, where 0<y≤4.4) and a lithium silicate (Li.sub.4SiO.sub.4) and having a D50 diameter of less than or equal to about 20 micrometers.

Methods of making a negative electrode material for an electrochemical cell that cycles lithium ions is provided. The method may include centrifugally distributing a molten precursor comprising silicon, oxygen, and lithium by contacting the molten precursor with a rotating surface in a centrifugal atomizing reactor. The molten precursor is formed by combining lithium, silicon, and oxygen. For example, the precursor may be formed from a mixture comprising silicon dioxide (SiO.sub.2), lithium oxide (Li.sub.2O), and silicon (Si). The method may further include solidifying the molten precursor to form a plurality of substantially round solid electroactive particles comprising a mixture of lithium silicide (Li.sub.ySi, where 0<y≤4.4) and a lithium silicate (Li.sub.4SiO.sub.4) and having a D50 diameter of less than or equal to about 20 micrometers.