Dielectric, structural and Raman investigations were carried out on a perovskite-based solid solution of (NBT)((1 - x))(BiCrO(3))(x) (x = 0.00, 0.05, 0.10 and 0.15). The crystal structure is rhombohedral, R3c, for these compositions and the anti-phase (a( - ) a( - ) a( - )) tilt angle decreases with increasing BiCrO(3) content. The temperature and frequency dependent dielectric measurements show that the phase transition temperatures T(d) and T(R - T) decrease, while T(m) increases, almost linearly with an increase in BiCrO(3) content. An anomalous increase in the relative dielectric permittivity is observed at higher temperature (T > T(d)) and higher BiCrO(3) content. However, at lower temperature (T < T(d)) the dielectric permittivity decreases with an increase in BiCrO(3) content. These effects are explained on the basis of the dynamics of oxygen defects produced due to charge compensation. The defect related bands are observed in the Raman spectra of (NBT)((1 - x))(BiCrO(3))(x).

Measurements of the ac-conductivity were carried out on (1 À x)NBT-xBiCrO 3 solid solution in the radio frequency range. The conductivity measurements suggest that with increase in BiCrO 3 content the electrical conductivity of sodium bismuth titanate (Na 0.5 Bi 0.5 TiO 3 ) (NBT) increases. For x ¼ 0.10 and 0.15 two relaxation behaviors are observed, related to long range conduction and short range hopping of defects. Activation energy calculated from dielectric relaxation as well as conductivity data reveals that both the processes are due to oxygen defects formed by substitution of chromium at titanium site. A reasonable decrease in the conductivity and dielectric loss were observed after oxygen annealing of the samples. Presence of relaxation peaks even after oxygen annealing suggests that relaxation is mainly by extrinsic oxygen defects produced due to substitution of chromium.

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