LAUSR

Abstract A series of BiFe1-xHf(3/4)xO3 ( 0%, 5%, 10%, 15% and 20%) nanoparticles were synthesized by simple auto combustion technique using citric acid as a fuel. Thermogravimetric (TGA), differential thermogravimetric (DTA), structural, magnetic, dielectric and ferroelectric analyses were investigated. Thermogravimetric analysis provides information of temperature at which phase develops (600 °C). DTA predicts ferroelectric to paraelectric transformation temperature which is found to be 822 °C. X-ray diffraction (XRD) results confirm formation of distorted rhombohedral structure for all compositions along with few traces of Bi25FeO40. The tolerance factor is increased from 0.845 to 0.853 due to larger ionic radius of Hf4+ substitution on Fe site. Crystallite size (D) is found in the range of 24.2–30.48 nm. Saturation magnetization (Ms) is increased to 16 times and remanent magnetization (Mr) is increased to 8 times than that of pure BiFeO3. This increment in magnetic parameters is due to reduction of oxygen vacancies, small crystalline size (less than 62 nm), structural distortion and unbalancing condition for antiferromagnetic magnetic moments of Fe3+ ions. Dielectric parameters depict decrement behavior with increasing of applied field up to 3 GHz. For Fe1-xHf(3/4)xO3, lower value of dielectric permittivity for all compositions is due to reduction of polarization and less growth of grains but more growth of grain boundaries because of mismatching of Hf and Fe3+ ions. P-E hysteresis loop changes from round shape to elliptical shape and it confirms less lossy nature of ferroelectric loops. Higher values of Ms as well as Mr but lower values of dielectric constant as well as remanent polarization for these nanoparticles make them useful for MeRAM (magnetoelectric random access memory) and high resonant applications.