A solid electrolyte includes lithium, phosphorus, sulfur, and halogen, in which, when the solid electrolyte is measured by TG-MS, a first peak derived from cyclic sulfur appears in a temperature range of 170° C. or higher and lower than 250° C., a second peak derived from the cyclic sulfur appears in a temperature range of 250° C. or higher and lower than 300° C., and a peak intensity P1 of the first peak is higher than a peak intensity P2 of the second peak.

Provided is an iron oxide powder for a brake friction material which can be suitably used in a brake friction material that is less likely to cause problems regarding brake squealing and that provides superior braking performance. The iron oxide powder for a brake friction material according to a first embodiment of the present invention is characterized by having a sulfur content of 150 ppm or less as measured by combustion ion chromatography, and a saturation magnetization of 20 emu/g or less. The iron oxide powder for a brake friction material according to a second embodiment of the present invention is characterized by having an average particle size of 1.0 μm or more, a chlorine content of 150 ppm or less as measured by combustion ion chromatography, and a saturation magnetization of 20 emu/g or less.

An adduct consists of derivatives of serinol pyrrole and of carbon allotropes in which the carbon is sp.sup.2 hybridized, such as carbon nanotubes, graham or nano-graphites or carbon black, in order to improve the chemical-physical properties of the allotropes increasing above all their dispersibility and stability in liquid media and in polymer matrices, and a process for preparation of the adduct.

It is intended to provide a carbon black which can confer reinforcing properties and low exothermicity, which are usually incompatible, as well as excellent abrasion resistance, when mixed with a rubber component, and is suitable for tire tread rubber that is used particularly under severe driving conditions. The present invention provides a carbon black having surface free energy γ.sup.d of 50 to 200 mJ/m.sup.2 determined by a reverse-phase gas chromatography analysis method and a strongly acidic group concentration of 0 to 0.115 μmol/m.sup.2.

Provided is a surface-modified nanodiamond having excellent dispersibility in an organic solvent, and a method capable of introducing various surface-modifying groups and easily producing surface-modified nanocarbon particles with little zirconia contamination. The surface-modified nanodiamond includes nanodiamond particles and a group that surface-modifies the nanodiamond particles and is represented by Formula (1): —X—R.sup.1 (1) [where X represents —NH—, —O—, —O—C(═O)—, —C(═O)—O—, —NH—C(═O)—, —C(═O)—NH—, or —S—; the bond extending left from X is bonded to a nanodiamond particle; R.sup.1 represents a monovalent organic group that does not have a hydroxy group, carboxy group, amino group, mono-substituted amino group, terminal alkenyl group, and terminal epoxy group; an atom bound to X is a carbon atom; and a molar ratio of carbon atoms to the total amount of heteroatoms selected from the group consisting of nitrogen atoms, oxygen atoms, sulfur atoms, and silicon atoms is 4.5 or greater.

A method for separating a metallofullerene M@C.sub.82, comprises steps of: a) adding a Lewis acid to an extract containing the metallofullerene M@C.sub.82 to react therewith, producing a complex precipitate; b) washing the precipitate, followed by dissolving and filtering to obtain a purified metallofullerene M@C.sub.82 extract, wherein M is one or more selected from the group consisting of lanthanide metals Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, and Lu; and the Lewis acid is one or more selected from the group consisting of zinc chloride, nickel chloride, copper chloride, zinc bromide, nickel bromide, and copper bromide.

Provided is an iron oxide powder for a brake friction material which can be suitably used in a brake friction material that is less likely to cause problems regarding brake squealing and that provides superior braking performance. The iron oxide powder for a brake friction material according to a first embodiment of the present invention is characterized by having a sulfur content of 150 ppm or less as measured by combustion ion chromatography, and a saturation magnetization of 20 emu/g or less. The iron oxide powder for a brake friction material according to a second embodiment of the present invention is characterized by having an average particle size of 1.0 μm or more, a chlorine content of 150 ppm or less as measured by combustion ion chromatography, and a saturation magnetization of 20 emu/g or less.

Provided is a method for producing a positive electrode active material for nonaqueous electrolyte secondary batteries, the method including: a mixing step of obtaining a W-containing mixture of Li metal composite oxide particles represented by the formula: Li.sub.zNi.sub.1-x-yCO.sub.xM.sub.yO.sub.2 and composed of primary particles and secondary particles formed by aggregation of the primary particles, 2 mass % or more of water with respect to the oxide particles, and a W compound or a W compound and a Li compound, the W-containing mixture having a molar ratio of the total amount of Li contained in water and the solid W compound or the W compound and the Li compound of 3 to 5 with respect to the amount of W contained therein; and a heat treatment step of heating the W-containing mixture to form lithium tungstate on the surface of the primary particles of the Li metal composite oxide particles.

The invention relates to a process for the preparation of a novel precipitated silica, wherein: a silicate is reacted with an acidifying agent, so as to obtain a silica suspension; said silica suspension is filtered, so as to obtain a filter cake; said filter cake is subjected to a liquefaction operation, optionally in the presence of an aluminium compound; wherein at least one polycarboxylic acid is added to the filter cake, during or after the liquefaction operation. It also relates to a novel precipitated silica and to its uses.

Provided is an iron oxide powder for a brake friction material which can be suitably used in a brake friction material that is less likely to cause problems regarding brake squealing and that provides superior braking performance. The iron oxide powder for a brake friction material according to a first embodiment of the present invention is characterized by having a sulfur content of 150 ppm or less as measured by combustion ion chromatography, and a saturation magnetization of 20 emu/g or less. The iron oxide powder for a brake friction material according to a second embodiment of the present invention is characterized by having an average particle size of 1.0 μm or more, a chlorine content of 150 ppm or less as measured by combustion ion chromatography, and a saturation magnetization of 20 emu/g or less.