Low-temperature synthesis of CuFeO2 (delafossite) at 70 °C: A new process solely by precipitation and ageing

• New process: low temperature synthesis of pure CuFeO2 nanoparticles.
• Synthesis at 70 °C within 24 h solely by precipitation and ageing.
• Nanoparticle characterization by XRD, FTIR, SEM, ICP–OES, TEM and Mößbauer.
• Special magnetic properties of nano-sized CuFeO2 synthesized at low temperatures.

This study presents a new low temperature synthesis method to obtain pure delafossite (Cu1+Fe3+O2) at a temperature of 70 °C within 24 h. For the first time delafossite is synthesized solely by precipitation and subsequent ageing process and without usage of any additives controlling the oxidation state of copper. The synthesized material, called LT-delafossite, consists of pure Cu1+Fe3+O2 exclusive of any side products. Rietveld analysis confirms the presence of both 3R (space group (SG): R-3m) and 2H (SG: P63/mmc) polytypes in LT-delafossite. Electron microscopy images show nanometer-sized hexagonal plates with a diameter <500 nm and a thickness of <30 nm. Measurements of the magnetic susceptibility from 2 K to 350 K in zero-field show one peak ∼18.5 K, which is attributed to an AFM phase transition. Zero-field-cooled magnetization data between −14 T and +14 T at 2 K revealed an s-shape form around the origin having no remanent magnetization.

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