Pure phase NiTiO3 was obtained via a modified sol-gel method. Addition of CeO2 in a modified oxidizing atmosphere in stearic acid at 750 °C led to the growth of several nanoscaled Ce-rich phases. The formation of NiTiO3 and CeO2/NiTiO3 was strongly confirmed based on metal-oxygen and metal-metal absorption bands. The nanometric formation of crystals and narrow distribution of nanoparticles were confirmed by XRD and FE-SEM. The magnetic properties indicated weak ferromagnetic behavior of NiTiO3 and paramagnetic behavior of CeO2/NiTiO3 nanocomposites. The paramagnetic properties were improved gradually into superparamagnetic upon increasing CeO2 domain to 30 mol%. It was observed that the current density can achieve 1 × 10-9 A/cm2 for the sample containing 30 mol% CeO2 at an electrical field equal to 40 V/cm.
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This work reported the successful synthesis of ilmenite-spinel (1 − x)NiTiO3-xMnFe2O4 (x = 0, 0.05 and 0.10) composites by a simple sol-gel method. Phase formation of composites was analyzed by the X-ray diffraction method. All the synthesized samples formed diphasic ilmenite-ferrite composites without any trace of impurity or intermediate phase. The optical properties of synthesized composites were characterized by diffuse reflectance UV–visible spectroscopy. MnFe2O4 phase modified the optical band gap of NiTiO3 material and shifted its optical bandgap value toward lower energy. Ferroelectric and magnetic hysteresis loops were investigated at room temperature. The hysteresis loops indicated the typical ferromagnetic and ferroelectric nature of all composites at room temperature. In P-E loops, the remanent polarization (Pr) and saturation polarization (Ps) showed a slight increase in the sample with 5% MnFe2O4 phase addition. However, the lossy P-E loop was observed in the sample with the addition of 10% MnFe2O4. The presence of ferrite MnFe2O4 phase in NiTiO3 material enhanced the magnetic properties of NiTiO3 at room temperature. The M-H loops of NiTiO3-MnFe2O4 composites presented a ferromagnetic behavior with a dramatic increase in saturation magnetization with an increase of ferrite phase addition.
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