Magnetic ordering of nickel hydroxide layers 30 Å apart obtained by intercalating dodecyl sulfate

Abstract

The nature of magnetic ordering in quasi-2D layered hydroxide of Ni (LH-Ni–DS) with hexagonal structure and synthesized by intercalating dodecyl sulfate (DS) ligand, (C12H25OSO3)−, between the layers using a hydrothermal technique is investigated. The observation of (00l) peaks up to l = 8 in x-ray diffraction on the sample yields an interlayer spacing c ≃ 30.5 Å and a crystallite size ≃ 16 nm. Assignment of the lines observed in the FTIR spectra to the various groups of the DS ligand confirms the intercalation. From the analysis of detailed investigations of the temperature dependence of the magnetization M at different magnetic fields, ac susceptibilities at frequencies from 0.1 to 1 kHz, and electron magnetic resonance spectra at 9.28 GHz, it is concluded that LH-Ni–DS orders ferromagnetically at TC ≃ 23 K. This TC is about 45% higher than TC ≃ 16 K reported for LH-Ni–Ac with c ≃ 8.6 Å obtained by intercalating an acetate ligand between the layers. The roles of the interlayer dipolar interaction, magnetic anisotropy and exchange interactions in determining TC in LH-Ni–L systems for several ligands L yielding different c-axes are discussed.