LAUSR

Abstract Co 2+ doped Mg–Zn spinel chromite compositions Mg 0.5 Zn 0.5- x Co x Cr 2 O 4 (0.0  ≤   x  ≤ 0.5) have been synthesized by the high-temperature solid state method. Synchrotron and X-ray diffraction (XRD) studies show single-phase crystalline nature. The structural analysis is validated by Rietveld refinement confirms the cubic structure with space group Fd 3 m . Crystallite size is estimated from Synchrotron XRD which was found to be 30–34 nm. Energy dispersive analysis confirms stoichiometric Mg 0.5 Zn 0.5- x Co x Cr 2 O 4 composition. Average crystallite size distribution is estimated from imaging software (Image – J) of SEM is in the range of 100–250 nm. Raman spectroscopy reveals four active phonon modes, and a pronounced red shift is due to enhanced Co 2+ concentration. Increased Co 2+ concentration in Mg–Zn chromites shows a prominent narrowing of band gap from 3.46 to 2.97 eV. The dielectric response is attributed to the interfacial polarization, and the electrical modulus study supports non-Debye type of dielectric relaxation. Ohmic junctions (minimum potential drop) at electrode interface are active at lower levels of doping ( x ac conductivity of Co 2+ doped Mg–Zn spinel chromites are suitable for power transformer applications at high frequencies.