Synthesis of Dense Fine-Grained Ceramics by Sol–Gel Technique of RE-substituted Bi_1−x A _x FeO₃ Nanopowders (A = La³⁺, Y³⁺, Dy³⁺, Ce³⁺): Structural, Electrical, and Magnetic Characterization

In this work, ceramics with the formula Bi_1−x A _x FeO₃ (A = La³⁺, Y³⁺, Ce³⁺ and Dy³⁺) using concentrations up to x = 0.20 were prepared by the sol–gel method. The effects of the diverse cations on the phase formation, grain size, as well as the electrical and magnetic properties were studied. The XRD results displayed the rhombohedral structure in all the ceramics as well as successful formation of single-phase compounds using lanthanum cations (x = 0.10 to 0.15). Scanning Electron Microscopy showed a non-homogeneous microstructure, consisting of grains with irregular morphology as well as the influence of the sintering method (spark plasma and conventional sintering) on the grain densification. Electric impedance spectroscopy measurements were performed to evaluate the electric properties, thus showing a slight increase in the permittivity values. Finally, the magnetic characterization showed an interesting increment in the coercive field up to ~7782 Oe with La³⁺ cations as well as a notable dependence with the dopant.