Phases Formed in Al-Doped Ni1 / 3Mn1 / 3Co1 / 3 ( OH ) 2 Prepared by Coprecipitation: Formation of Layered Double Hydroxide

Abstract

The coprecipitation process, using either mixed nitrate or sulfate solutions, to produce Al-doped has been studied in detail. Using X-ray diffraction (XRD) and thermal gravimetric analysis (TGA), it has been determined that charge-compensating or ions accompany the incorporated ions into the structure to form layered double hydroxides (LDHs). The phases formed were determined for in and . For , two phase mixtures between (, Mn, and Co) and the LDH phase with were formed. For aluminum contents greater than , XRD and TGA experiments suggest that the excess Al is present as and that the product is a mixture of or and , where M represents the mixture of Ni, Mn, and Co. Alternatively, the data can also be explained assuming that samples with are single phase . TGA experiments show that the in the -containing LDH is eliminated at lower temperature than the in the -containing LDH. Thus coprecipitations using nitrates may be preferred in situations where excellent cation mixing is desired in the production of Al-doped .