Patent attributes
Diamond clusters are used as a polishing material of free abrading particles, each being a combination of artificial diamond particles having primary particle diameters of 20 nm or less and impurities that are attached around these diamond particles. The density of non-diamond carbon contained in the impurities is in the range of 95% or more and 99% or less, and the density of chlorine contained in other than non-diamond carbon in the impurities is 0.5% or more and preferably 3.5% or less. The diameters of these diamond clusters are in the range of 30 nm or more and 500 nm or less, and their average diameter is in the range of 30 nm or more and 200 nm or less. Such polishing material is produced first by an explosion shock method to obtain diamond clusters and then removing the impurities such that density of non-diamond carbon contained in the impurities and density of chlorine contained in other than non-diamond carbon in the impurities become adjusted.
