Structural, magnetic, optical, and dielectric properties of Ga-K substituted BiFeO3 ceramics

Gallium was substituted in Bi0.97K0.9Fe1-xGaxO3 (x = 0.00, 0.04, 0.08, 0.12, and 0.16) and synthesized using a simple citrate sol-gel technique. Structural, magnetic, dielectric, and optical properties were investigated. XRD patterns revealed two intense peaks (110) and (104) merged into a single peak for x = 0.08 and induced structural phase from rhombohedral to orthorhombic symmetry. Cell volume was decreased with the substitution of K-Ga up to x = 0.12. The crystallite size lies in the range of 17.90-45.71 nm. Bulk density was reduced from 2.36 to 2.24 g/cm(3) because bigger ionic incorporation resulted in less diffusion at grain boundaries, increasing inner pores. The optical analysis confirmed that the Ga-O bond length was more significant than the Fe-O bond length, and the Fe-O bond length was stretched with Ga incorporation in BKFO. For x = 0.12, dielectric constant and dielectric loss decreased due to the Ga3+ ion's stable ion yield reduction of Fe3+ at octahedral sites. So, the hopping of electrons between Fe3+ and Fe2+ becomes tricky, and electron accumulation occurs at the interface of grain boundaries which hampers and decreases dielectric polarization. These results suggested that synthesized materials may be applicable in dielectric resonators, magnetic field sensors, and magnetoelectric coupling.