Structural, optical and multiferroic properties of (1-x)BiFeO₃-xNa_0.5Bi_0.5TiO₃, x = 0.00, 0.05, 0.10 and 0.15

The polycrystalline (1-x)BiFeO₃-xNa_0.5Bi_0.5TiO₃, x = 0.00, 0.05, 0.10 and 0.15, ceramics were prepared using conventional solid-state route. The structural studies using X-ray diffraction and Raman measurements confirmed the rhombohedral R3c structure of the compounds. The scanning electron micrographs showed that grain size decreased, and the density of the compounds increased with the higher Na_0.5Bi_0.5TiO₃ content. The weak ferromagnetism was induced in the solid solution of antiferromagnetic BiFeO₃ compound with Na_0.5Bi_0.5TiO₃ content. The structural distortions were increased with the increase of x, which favours the increase of weak ferromagnetism in the antiferromagnetic compound. The electric polarisation measurements indicated that leakage character decreased with the increase in Na_0.5Bi_0.5TiO₃ fraction. The temperature and frequency-dependent dielectric measurements showed that the dielectric constant was improved and loss tangent was decreased in Na_0.5Bi_0.5TiO₃ rich compounds. The temperature dependence of dielectric constant data showed a dielectric anomaly near the magnetic transition of BiFeO_3, which shifted towards the lower temperature side with the increase of x. The UV-VIS-NIR spectroscopy measurements evidenced an increase in band gap energy for higher Na_0.5Bi_0.5TiO₃ concentration.

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