Synthesis and Characterization of Sodium Potassium Niobate and Cobalt Ferrite Multiferroic Composites

Abstract

ABSTRACTThe composite materials with composition xNa0.5K0.5NbO3-(1–x)CoFe2O4 with x = 0.2, 0.4, 0.5, 0.6, 0.8, 0.9 and 1.0 are combination of ferroelectric Na0.5K0.5NbO3 (NKN) and ferrimagnetic CoFe2O4 (CFO) compounds. NKN is a combination of ferroelectric KNbO3 and antiferroelectric NaNbO3, with morphotropic phase boundary and exhibits two phase transitions around 220°C and 430°C. CFO is a ferrimagnetic material with inverse spinel cubic structure. Therefore the triphasic composite is expected to be a good magneto-electric material. NKN is synthesized by solid state double sintering method. XRD studies confirm single phase formation and orthorhombic structure. The composites are fabricated by taking stoichiometric amounts of NKN and CFO powders, ground for 6 h, made into green square pellets and kept for sintering at 1000°C for 5 h. XRD studies reveal the presence of peaks corresponding to both NKN and CFO. Density of the composites increased with addition of CFO; SEM images indicate the change in shape and size of grains. EDS studies confirm the presence of estimated atomic and weight percentages of all the composites. FTIR studies reveal the presence of multiple peaks in the 1000-1600 cm–1 region due to Na-O, K-O vibrations and at ∼450 and 584 cm–1 due to Fe-O and Co-O bonds. Dielectric measurements show the variation of transition temperatures with the change in composition. Impedance studies confirm the increasing conducting behaviour of composites with increasing concentration of CFO.