Patent ID: 7927391

Claim:
Process for the manufacture of a ceria based polishing composition, comprising (a) suspending an inorganic cerium salt or cerium hydroxide with a cerium content calculated as cerium oxide in the range of 50%-100% based on Total rare earth oxide (TREO) in an aqueous medium thereby obtaining an aqueous suspension, which aqueous suspension is treated with an acid or a salt of an acid selected from the group of HF, H 3 PO 4 and H 2 SO 4 , thereby obtaining a solid suspended in said aqueous medium, (b) separating said solid from said aqueous medium, and (c) calcining the separated solid at a temperature between 750° C. and 1,200° C. and grinding the calcined solid to grain sizes in the range of 0.5 μm to 5.0 μm.