Doping dependent phase fractions in hydrothermally synthesized Mn doped CuFeO2

Using a simple hydrothermal method, CuFe1−xMnxO2 delafossite materials are produced and investigated by means of X-ray diffraction, ultraviolet-visible reflectance measurements, and electron microscopy. Up to nominally x = 0.3, the synthesis yields delafossite material, which generally consists of both the 2H and R3 phase without any impurities. Lattice parameters and the indirect optical band gap of delafossite close to about 1.3 eV decrease upon increasing Mn content, which confirms the successful doping with Mn up to an actual Mn content of x = 0.05. The 2H phase fraction shows a pronounced and peaked dependence on Mn content with a maximum 2H mass fraction of about 27% at nominally x = 0.01, whereas the hexagonal particle morphology and the platelet size of about 500 nm as measured by both scanning and transmission electron microscopy are independent from the latter.