Enrichment of optical, electrical, and magnetic properties of Li~+, La~(3+) doped BaTiO_3 perovskite multifunctional ceramics

摘要

Li and La co-doped Ba_((1-x))(Li_(x/2)La_(x/2))TiO_3 (BLLT) ceramics with x = 0.01, 0.02, 0.03, and 0.04 at A-site was synthesized by sol-gel combustion method. The powder X-ray diffraction and Raman analysis showed a good crystalline nature with perovskite tetragonal structure and the grain size of the samples was estimated and compared using a scanning electron microscope. The decreasing trend in the optical band gap upon doping and carrier concentration values was calculated from UV-Vis absorption spectra. Electron paramagnetic resonance g ～ 1.998 for BLLT ceramics confirms that the electrons are localized near oxygen vacancies. The observed signals may be attributed to the reduction of Ti~(4+)/Ti~(3+) and its related defects. Moreover, the room temperature magnetization versus magnetic field loops showed the mixed weak ferromagnetic and diamagnetic phase. The enhancement of ε' with respect to the doping of Li and La ion and increase in particle size due to the number of grain boundaries in BLLT ceramics were studied. The polarization versus electric field of BLLT samples indicates the lossy capacitor behavior, which is attributed to the relatively high leakage current caused by the existence of a defect or oxygen vacancies.