Spinel powder and spinel slurry

A spinel powder represented by a chemical formula MgAl2O4, wherein the spinel powder has a specific surface area of 55 m2/q or more and an average diameter of from 3 to 20 μm;

• and
• pores in the spinel powder having diameters falling within a range of d±d/2 from a mean pore diameter d, where 11 nm≦d<50 nm, form at least 70% of the total pore volume of the spinel powder;
• and
• the spinel powder is produced by a process comprising
• drying a solution containing a water-soluble organic substance having a boiling point of 120° C. or above to form a dried substance, and
• converting the dried substance into a complex oxide by heating and then milling.

A spinel powder represented by a chemical formula MgAl2O4, wherein the spinel powder has a specific surface area of 55 m2/q or more and an average diameter of from 3 to 20 μm;

• and
• pores in the spinel powder having diameters falling within a range of d ±d/2 from a mean pore diameter d, where 11 nm≦d<50 nm, form at least 70% of the total pore volume of the spinel powder;
• and
• the spinel powder is produced by a process comprising
• drying a solution containing an aluminum salt of a water-soluble carboxylic acid and a magnesium salt of a water-soluble carboxylic acid to form a dried substance, and
• converting the dried substance into a complex oxide by heating.

A spinel powder comprising MgAl2O4 as a main component,

• wherein the spinel powder has a specific surface area of 42 m2/q or more and an average diameter of from 3 to 20 μm;
• and
• pores in the spinel powder having diameters falling within a range of d±d/2 from a mean pore diameter d, where 11 nm≦d<50 nm form at least 70% of the total pore volume of the spinel powder;
• and
• the spinel powder is produced by a process comprising
• mechanically mixing and milling a mixture of hydroxides to form a complex hydroxide,
• mixing the complex hydroxide with an unconverted hydroxide to form a mixture, and
• heating the mixture to form a complex oxide.