Ge-doping effect on the optical, magnetic, and dielectric properties of CuBO2 delafossite oxides

Abstract

In this work, we report the microstructural, optical, magnetic, and dielectric properties of CuB1-xGexO2 (x = 0.00, 0.01, and 0.03) prepared using a solid-state reaction method. These properties were investigated using several techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible spectroscopy, vibrating sample magnetometry (VSM), and impedance analysis. We found that all samples had a main crystal structure of the 3 R delafossite (space group R-3 m). For the doped samples (x = 0.01 and 0.03), a secondary phase of CuGeO3 was observed. All the powder samples had an average particle size of approximately 300 nm with an irregular hexagonal shape. These samples showed a strong absorbance peak at a wavelength centered at 250 nm, which indicated a direct optical bandgap in range of 2.91–2.96 eV. Ferromagnetism was achieved in the Ge-doped samples at 50 K. Finally, colossal dielectric permittivity was observed in both undoped and Ge-doped ceramic samples.