Structural and physical properties of Ge-doped CuCrO2 delafossite oxide

Ge-doped CuCrO2 delafossite semiconductors were synthesized using a conventional solid-state reaction method. The influence of Ge concentration (0-5%) on its microstructural, optical, and magnetic properties were investigated. X-ray diffraction (XRD) analysis results revealed the delafossite structure in all the samples. There is no significant difference in the lattice spacing of CuCr1-xGexO2 samples with increasing substitution of Ge at the Cr site. This indicated that the Ge entrance into the Cr sublattice in the form of Ge2+, and Ge4+ ions in CuCr1-xGexO2 ceramics, which is further certified by X-ray photoelectron spectra. The optical properties measured at room temperature by UV-visible spectroscopy showed a weak absorbability in the visible light and near IR regions. The corresponding direct optical band gap was about 3.61 eV, exhibiting transparency in the visible region. The magnetic hysteresis curve measurements showed that the Ge-doped CuCrO2 samples exhibit paramagnetic behavior at room temperature. However, ferromagnetism is achieved in the Ge-doped CuCrO2 samples at 50 K. The magnetization of this CuCr1-xGexO2 delafossite is increased almost linearly with the increasing Ge concentration. This indicated that the combined influence of the number of the M-M pairs, and long-range and short-range interactions of M-M couplings produce a mixed effect on the magnetic properties of CuCrO2 delafossite oxide. The dielectric measurements clearly revealed the dielectric permittivity of CuCrO2 strongly inhibited by Ge doping.