Oxidation state of chromium in (Na_0.5Bi_0.5TiO₃)_(1−x)(BiCrO₃) _x solid solution; investigated by XAS and impedance spectroscopy

X-ray absorption spectroscopy (XAS) and impedance spectroscopy have been used to study the oxidation state of chromium in (Na_0.5Bi_0.5TiO₃)_(1−x)(BiCrO₃) _x solid solution. XAS measurements reveal that chromium ion occupies the octahedral site in Na_0.5Bi_0.5TiO₃ (NBT). The increase in chromium content increases the distortion in chromium-oxygen octahedral. No shift in the Cr–K edge was observed with increase in chromium content. The XAS measurements suggest that chromium exists either as +3 or +5 state in (Na_0.5Bi_0.5TiO₃)_(1−x)(BiCrO₃) _x . The impedance measurements show a considerable increase in the electrical conductivity with increase in chromium content. The activation energy for conduction mechanism was found to lie between 0.50 and 0.7 eV for all the samples. These measurements indicate that main contribution to the conductivity is because of oxygen defects generated by the incorporation of chromium at B-site of NBT.