Structural, magnetic and dielectric properties of vanadium substituted four layered Aurivillius Bi5FeTi3O15 ceramics

The present work reports the study of four layer Aurivillius compound Bi5FeTi3O15 (BFTO) with V5+ (<= 50%) doping at B-site (Fe3+, Ti4+). This is considered to be equivalent of increasing the magnetic ion (Fe3+) concentration from 25% to 37.5%. Phase purity of the samples is confirmed with lab and synchrotron based x-ray diffraction measurements. The temperature dependent magnetization measurements indicate the paramagnetic nature of BFTO down to 2 K and the development of long-range antiferromagnetic (AFM) ordering with V5+ doping. It is observed that the AFM Neel transition temperature (T-N) decreases with increase of V5+ doping. The presence of iron oxide impurity phases is excluded from the Fe-57 Mossbauer spectroscopy measurements. Temperature dependent dielectric constant measurements show the relaxation behaviour in highly doped samples.