Abstract: Isometric iron oxide pigments are prepared by an improved process by precipitation of aqueous solutions containing iron (II) salts with alkaline precipitating agents followed by oxidation of the precipitate at temperatures of from 20.degree. C. to 100.degree. C., wherein the improvement comprises adjusting the iron (III) content to 1 to 25 mol %, based on the total iron, before precipitation.

Abstract: A heat-stable iron oxide black pigment resistant to hydrothermal treatment in air at temperatures above 180.degree. C. and which has a specific BET surface of 0.5 to 5 m.sup.2 /g is useful as a coloring agent for building materials, paints, cements, bricks and so forth and is prepared by reacting an aqueous solution of FeOOH, iron (II) salts and alkalis at elevated temperature and precipitating iron oxide from the solution with Na.sub.2 CO.sub.3 at temperatures in the range from 80.degree. C. to the boiling point of the solution.

Abstract: Acicular magnetic iron oxide pigments are disclosed which have a Co content of 1 to 5% by weight and an FeO content of 5 to 12% by weight. The pigments may optionally contain an additional dopant selected from zinc, phosphate and SiO.sub.2. The pigments are useful in magnetic recording media such as video tapes.

Abstract: Highly-coercive isometric iron oxide useful in magnetic toners for electrostatic photo-copying processes or for magnetic printers is produced by(a) subjecting Fe.sub.3 O.sub.4 pigment produced in a wet process to oxidation and(b) subsequently reducing the oxidized pigment from (a) to produce highly-coercive Fe.sub.3 O.sub.4 pigment.

Abstract: Pigments for printing inks and magnetic toners are iron oxide pigments with a rhombic dodecahedral form and an average particle diameter of from 0.05 to 3.0 .mu.m with a standard deviation of the particle size distribution of .+-.30%.

Abstract: Improved iron oxide pigments useful in the manufacture of magnetic recording carriers or for coloring inorganic or organic materials are iron oxide pigments having an iron (II) content of at least 5% by weight calculated as FeO after-treated with a phenolic compounds of the formula ##STR1## wherein X is O or NH, andR is straight chained or branched alkyl with 1 to 30 carbon atoms, alkenyl with 2 to 30 carbon atoms, cycloalkyl with 5 to 12 carbon atoms, or hydrogen.

Abstract: A bright, color-pure iron oxide red pigment is produced by an improved process by precipitation of iron(II) salts in aqueous solution with an alkaline precipitating agent, oxidation at temperatures of from 20.degree. C. to 100.degree. C. and annealing of the resulting precipitation products under air to form iron oxide red pigments, wherein the improvement comprises before adding the alkaline precipitating agent, the iron(III) content of the aqueous solution is adjusted to 1 to 15 mol %, based on the total iron content of the iron salt solution.

Abstract: In improved cobalt coated magnetic iron oxide having increased coercive field strength and highly efficient for use in magnetic recording devices and processes is produced by subjecting uncoated magnetic iron oxide particles to an acid treatment and then epitaxially coating the treated particles with cobalt.