Powder and film of nickel and iron-layered double hydroxide: Elaboration in polyol medium and characterization

Two main reactions occur in polyol media: reduction and hydrolysis. In the case of systems with two easily reducible elements, Ni and Fe for instance, previous works have shown that bimetallic particles or the oxide spinel particles can be obtained. This paper shows that polyols can also be used to elaborate layered double hydroxides (LDH)–Ni–Fe. In this case, the hydrolysis ratio must be adjusted to avoid both reduction and oxolation reactions in favor of hydroxylation. The compound can be obtained either in powder or in gel forms. The gel enables elaboration of film by spin-coating process. The compound is poor-crystallized and exhibits a turbostractic character. Its interlamellar distance (12.89 Å) is slightly higher than that of a similar compound elaborated in aqueous solution via the titration method (12.02 Å). 57Fe Mössbauer spectrometry allows concluding the presence of HS Fe3+ cations, which occupy two different octahedral sites. XRD and Mössbauer studies reveal interesting preferential orientation features of the film with an anisotropy of the crystalline grains having their c-axis perpendicular to the film.