METHOD FOR PRODUCING NEGATIVE THERMAL EXPANSION MATERIAL, METHOD FOR PRODUCING REACTION PRECURSOR OF NEGATIVE THERMAL EXPANSION MATERIAL, REACTION PRECURSOR OF NEGATIVE THERMAL EXPANSION MATERIAL, AND NEGATIVE THERMAL EXPANSION MATERIAL

摘要

This method for producing a negative thermal expansion material comprises: a step for dissolving, in a neutral or acidic solution, a bismuth salt, a nickel salt, a salt of a metal M capable of forming a trivalent ion, and optionally a rare-earth element salt or an antimony salt, to form a metal salt solution; a step for mixing the metal salt solution with a hypohalite salt and an alkaline compound and causing a metal salt to precipitate, to form a reaction precursor; and a step for pressurizing and heating the reaction precursor, to form a negative thermal expansion material containing a compound wherein, in BiNiO3, a portion of Bi is substituted by the rare-earth element or Sb and/or a portion of Ni is substituted by the metal capable of forming a trivalent ion.