Structural, magnetic and dielectric properties of Bi₄Nd_0.5Gd_0.5Ti₃FeO₁₅ ceramics

Single-phase Aurivillius Bi₄Nd_0.5Gd_0.5Ti₃FeO₁₅ ceramics was synthesized via the solid-state reaction technique. Rietveld refinement of the full XRD pattern was carried out to obtain the detailed structure of the compound. Dielectric response and electrical properties of the ceramics were investigated in a wide range of frequency and temperature by dielectric/impedance spectroscopies. Two dielectric relaxations were distinguished, which were attributed to grains and grain boundaries respectively, by the combination of impedance and modulus analysis. Resistance of grain boundaries was determined much larger than that of grains. The kinetic analysis of temperature dependent dielectric data was performed to study the corresponding relaxation-conduction behaviors in the material. The thermal magnetization measurement evidenced the paramagnetic characteristic of the material, but localized antiferromagentic coupling would exist below 200 K. In addition, a phase transition was observed at ∼240 °C.