Abstract: An object of the present invention is to provide an inorganic core/shell particle to be contained in an abrasive material that contains a reduced amount of cerium, can polish harder workpieces at a high polishing rate, and can decrease the surface roughness of the workpieces. The inorganic core/shell particle P of the present invention is to be contained in an abrasive material and includes a core (1) containing a salt of at least one element selected from yttrium (Y), titanium (Ti), strontium (Sr), barium (Ba), samarium (Sm), europium (Eu), gadolinium (Gd), and terbium (Tb) and a shell (2) containing a salt of at least one element selected from these eight elements and a salt of cerium (Ce), wherein the crystallites in the shell (2) have an average diameter within a range of 4 to 30 nm.

Abstract: Method to obtain a highly pure reclaimed polishing material from a polishing-material slurry including already used polishing material. A polishing material is reclaimed from a polishing-material slurry including already used polishing material by undergoing: recovering the polishing-material slurry used to polish an object having silicon as a main component thereof; adjusting the pH of the recovered polishing-material slurry to be in the range of 7-10; adding an alkali earth metal-containing metal salt as an inorganic salt to the pH adjusted polishing-material slurry, to cause the polishing material to agglomerate, and the polishing material is separated from the mother liquor and concentrated; and the polishing material, having been separated and concentrated, is subjected to solid-liquid separation, and recovered.

Abstract: Method to obtain a highly pure reclaimed polishing material from a polishing-material slurry including already used polishing material. A polishing is reclaimed from a polishing-material slurry by undergoing: recovering in step (A) a polishing-material slurry including already used polishing material; adding in step (B) an alkali earth metal-containing metal salt to the recovered polishing-material slurry to cause the polishing material to agglomerate, and the polishing material is separated from the mother liquor and concentrated; the polishing material, having had been separated and concentrated, is subjected in step (C) to solid-liquid separation, and recovered; and using in step (D) a magnetic filter to filter and remove metal particles included in the polishing-material slurry. Step (D) is performed at the same time as step (B) or step (C), or performed after either step (A), step (B), or step (C).