Effect of Cobalt Doping on Structural, Morphological, Magnetic, Electrical, and Optical Properties of (Ba_0.7Sr_0.3)_0.98Ca_0.02Ti_1−XCo_xO₃ Ceramics for Device Applications

Abstract

Considering the multifunctional performance, the (Ba0.7Sr0.3)0.98Ca0.02Ti1−xCoxO3 (x = 0.00–0.2) ceramics are successfully synthesized using the traditional solid‐phase reaction method. The effect of cobalt doping on the samples’ structural, morphological, magnetic, electrical, and optical characteristics is elucidated. Raman spectroscopy and X‐ray diffraction data confirm the dopants’ integration into the cubic perovskite microstructure. At room temperature, the magnetization–magnetic field intensity hysteresis loops from vibrating sample magnetometer reveal the samples’ ferromagnetic character, with a maximum magnetization of 0.091 emu g−1 achieved for x = 15%. The real part of the initial permeability demonstrates that the replacement of Co2+ causes a shift in resonance toward higher frequencies above 85 MHz, indicating the potential of the synthesized ceramics for high‐frequency magnetic applications. The variation in dielectric characteristics from 100 Hz to 10 MHz is explained using electron hopping on octahedral sites and Maxwell–Wagner's model. The increase of AC conductivity in the high‐frequency region is consistent with the strengthening of the grain effect on the conduction mechanism, which supports the small‐range polaron‐hopping theory. The complex electric modulus's peak (M′′) shifts toward a higher‐frequency region with cobalt content, suggesting a reduction in the relaxation rate. The optical bandgap is observed to decrease from 3.08 to 2.96 eV with cobalt content.