Structural, morphological and magnetic properties of novel sol-gel derived Bi_1-xGd_xFe_0.85Mn_0.15O₃ solid solutions

In the present work, the influence of annealing temperature and chemical composition on the structural, morphological, and magnetic properties of Bi_1-xGd_xFe_0.85Mn_0.15O₃ solid solutions prepared by sol–gel technique was studied. Structural properties were investigated by X-ray diffraction, Raman, FT-IR, and Mӧssbauer spectroscopies, while morphological features were evaluated by scanning electron microscopy (SEM). The low concentration of Gd³⁺ ions can be introduced into BiFe_0.85Mn_0.15O₃ perovskite structure at 500 °C annealing temperature, while heating at higher temperatures (650 °C and 800 °C) resulted in the formation of products in the whole compositional range (x = 0–1). Depending on the chemical composition few different structural regions were observed for solid solutions annealed at 800 °C, including a trigonal, mixture of orthorhombic and trigonal, and orthorhombic unit cells. Gd–induced paramagnetic contribution to magnetization is proportional to the amount of Gd³⁺ ions. Magnetic properties were determined to be dependent on the annealing temperature of synthesis product.