Probing of structural phase transitions in barium titanate modified sodium niobate using Raman scattering

Abstract

AbstractRaman spectroscopic measurements are carried out to investigate the structural phase transitions as a function of composition in modified sodium niobate [(1‐x) NaNbO3‐xBaTiO3:NNBTx] for x = 0.0 to 0.15 at room temperature. The characteristic antiferroelectric modes at around 93.4 and 123.6 cm−1, along with a mode at 155.5 cm−1 were found to disappear across the structural phase transition from antiferroelectric orthorhombic phase (Pbcm) to ferroelectric orthorhombic phase (Pmc21) for x > 0.02. The redistribution of intensities and positions of the Raman lines in bending (150–350 cm−1) and stretching modes (>550 cm−1) on increasing the concentration x > 0.05, also confirms the occurrence of another phase transition from ferroelectric orthorhombic phase (Pmc21) to another ferroelectric orthorhombic phase (Amm2) phase across x~0.10. The phase transitions as observed from Raman measurements are consistent with previous X‐ray diffraction study.