Influence of GdFeO₃ addition on the physical properties of NaKNbO₃ lead free ferroelectric ceramics

Polycrystalline samples of (1-x) Na_0.5K_0.5NbO ₃-(x) GdFeO₃ (designated as NKN-GF) (x=0.01, 0.02, 0.04, 0.6 and 0.10), were prepared by a conventional solid-state reaction technique. Preliminary structural studies at room temperature suggest that compounds are formed in a single perovskite phase. Compositions with x=0.02-0.04 possess orthorhombic structure while for x=0.06-0.10 show tetragonal structure. The diffraction peaks shift slightly to a higher angle with increasing concentration of x. The ferroelectric phasetransition of these materials, shows a shift in the transition temperature towards the higher-temperature side with increased GF concentration. The magnetization increases with the increase in GF content which is clearly perceptible in the evolution of hysteresis loops indicating that GdFeO₃ doped NKN has introduced ferromagnetic contribution. This may be attributed to variation in the oxygen stoichiometry, doping at different crystallite sites and change in the magnetic anisotropy.