Provided are methods for manufacturing improved cerium oxide abrasives suitable for forming slurry compositions suitable for CMP processes. The cerium oxide abrasives are produced by the heat treatment of a mixture of a cerium precursor compound under conditions that produce primary cerium oxide particles that are incorporated in larger secondary abrasive particles. The structure of the primary cerium oxide particles and/or the presence of incompletely oxidized cerium within the secondary abrasive particle tend to reduce its mechanical strength, thereby reducing the likelihood of damaging a substrate surface during a CMP process utilizing such abrasives.