Abstract
In the present work, we investigated the correlation between structure, microstructure, optical, electrical, dielectric and magnetic properties in composites based on ferrimagnetic Sr0.92Ca0.04Mg0.04Fe12O19 (noted SrCaMg) and ferroelectric BaTiO3 (noted BTO) phases in different ratio. Series of (1-x)BaTiO3/xSr(0.92)Ca(0.04)Mg(0.04)Fe(12)O(19) mixtures (with x = 0.00, 0.25, 0.50, 0.75 and 1.00) were synthesized. The constituents were selected by taking into consideration the perspective ferroelectric and ferrimagnetic characteristics of BaTiO3 and Sr0.92Ca0.04Mg0.04Fe12O19, respectively. X-ray diffraction (XRD) investigations showed the co-existence of tetragonal BaTiO3 (noted BTO hereafter) and Sr0.92Ca0.04Mg0.04Fe12O19 hexagonal ferrite (noted SrCaMg HF) phases in the produced composites. The phase content of ferrimagnetic SrCaMg HF phase is increasing with increasing x content. The lattice parameter 'a' for both BTO and SrCaMg HF phases is almost constant with increasing the x content. However, the lattice parameter 'c' is decreasing for BTO phase and increasing for SrCaMg HF phase. The crystallites size (D-XRD) is decreasing for BTO phase and increasing in SrCaMg HF phase as the x content increases. The homogeneous distribution of different phases was confirmed via scanning and transmission electron microscopies analyses and the corresponding selected area electron diffraction (SAED) patterns. On increasing the content of SrCaMg hexaferrite phase, the grains size of BTO phase is decreasing. The band gap energy (E-g) values were determined from the analysis of UV-vis diffuse reflectance spectra. BTO nanoparticles (x = 0.00) displays E-g value equal to 3.27 eV. It is found that E-g value is reduced with increasing the concentration of SrCaMg hexaferrite phase reaching values of 3.21, 3.08, 2.91 and 1.23 eV for x = 0.25, 0.50, 0.75 and 1.00, respectively. The saturation magnetization (M-s) and remanence (M-r) were increased with increasing the concentration of SrCaMg HF in the composite. M-s and M-r values are increased from about 0.09 and 0.02 emu/g for x = 0.00 to around 68.8 and 44.7 emu/g for x = 1.00. Compared to x = 0.00 sample, the coercivity (H-c) was increased sharply from 400.5 to 3295 Oe for x = 0.25 and then slightly diminishes with further increasing x. It was noticed that the dielectric properties of various composites depend largely on the x content that alters the microstructure of composite. This was discussed with respect to the microstructure and temperature effect.