Abstract: A polishing liquid is provided containing manganese oxide abrasive grains, permanganate ions, and a cellulosic surfactant or a cationic surfactant. The polishing liquid has a pH of 5 or more and 11 or less. The cellulosic surfactant is preferably a carboxymethyl cellulose or a derivative thereof. The cationic surfactant preferably has a quaternary ammonium ion site. The content of the cellulosic surfactant or the cationic surfactant is preferably 0.01 mass % or more and 1.0 mass % or less based on the total amount of the polishing liquid.

Abstract: A polishing slurry according to the present invention contains: abrasive grains made of a metal oxide; a permanganate; and an inorganic compound other than the permanganate. The inorganic compound is such that a solution that is obtained by adding the inorganic compound to a 1.0 mass % aqueous solution of the permanganate so that the inorganic compound accounts for 1.0 mass % of the resultant aqueous solution has an oxidation-reduction potential higher than that of the 1.0 mass % aqueous solution of the permanganate. It is preferable that the inorganic compound be contained in an amount of 0.7 parts by mass or more and 150 parts by mass or less relative to 100 parts by mass of the permanganate. It is also preferable that the abrasive grains made of a metal oxide be manganese oxide particles.

Abstract: A polishing liquid contains permanganate ions, a weak acid, and a soluble salt of the weak acid. The polishing liquid preferably has a pH of 0.5 to 6.0 at 25° C. before commencement of polishing. When a 0.1 mol/L aqueous solution of sodium hydroxide is added to 100 mL of the polishing liquid having been adjusted to pH 3.0 to 4.0 at 25° C., the amount of the sodium hydroxide aqueous solution necessary to raise the pH of the polishing liquid by 0.5 is preferably 0.1 to 100 mL. The weak acid is preferably acetic acid.

Abstract: A polishing liquid is provided containing manganese oxide abrasive grains, permanganate ions, and a cellulosic surfactant or a cationic surfactant. The polishing liquid has a pH of 5 or more and 11 or less. The cellulosic surfactant is preferably a carboxymethyl cellulose or a derivative thereof. The cationic surfactant preferably has a quaternary ammonium ion site. The content of the cellulosic surfactant or the cationic surfactant is preferably 0.01 mass % or more and 1.0 mass % or less based on the total amount of the polishing liquid.

Abstract: A polishing slurry according to the present invention contains: abrasive grains made of a metal oxide; a permanganate; and an inorganic compound other than the permanganate. The inorganic compound is such that a solution that is obtained by adding the inorganic compound to a 1.0 mass % aqueous solution of the permanganate so that the inorganic compound accounts for 1.0 mass % of the resultant aqueous solution has an oxidation-reduction potential higher than that of the 1.0 mass % aqueous solution of the permanganate. It is preferable that the inorganic compound be contained in an amount of 0.7 parts by mass or more and 150 parts by mass or less relative to 100 parts by mass of the permanganate. It is also preferable that the abrasive grains made of a metal oxide be manganese oxide particles.

Abstract: The present invention provides a polishing technique capable of polishing, at a high speed, a substrate containing Al and having high hardness, such as single-crystal sapphire substrate, and capable of providing a polished surface of high accuracy. The present invention relates to a polishing slurry for polishing a substrate containing aluminum, comprising abrasive grains, an inorganic boron compound having a solubility in water at 20° C. of 0.1 g/100 g—H2O or more, and water. In the present invention, it is preferable that the content of the inorganic boron compound is 0.1% by mass to 20% by mass in terms of boron atoms based on the polishing slurry.