Chemical modification is an effective method for obtaining functional materials with desired properties for technological applications. In this work, the high-pressure prepared BiFeO \(_3\) compounds with partial substitution of Bi by Tb ions were studied. The microstructures, phonon modes, and macroscopic magnetic properties of the Bi \(_{1-x}\) Tb \(_x\) FeO \(_3\) compounds with \(x =\) 0.05, 0.1, and 0.3 were investigated. It was demonstrated that the obtained bulk ceramics crystallized in pure rhombohedral (for \(x =\) 0.05 and 0.1) or orthorhombic ( \(x =\) 0.3) structure with reduced microstrains. The Tb ions within the crystal structure and high-pressure annealing had a minimal effect on the phonon modes in the rhombohedral phase, but the magnetic properties were improved in comparison to pristine BiFeO \(_3\) . The impact of chemical modifications and high-pressure annealing on the suppression of spin cycloid and the appearance of weak ferromagnetism was discussed.
