Investigation on the Structural, Optical, and Vibrational Properties of Lead-Free (1−x) Na₀.5Bi₀.5TiO₃-xBiMnO₃ Ceramics

Single-phased [(1 − x) NBTxBMO, x = 0.01 (NBTBM1), (1 − x) NBTxBMO, x = 0.02 (NBTBM2), (1 − x) NBTxBMO, x = 0.03 (NBTBM3), and (1 − x) NBTxBMO, x = 0.04 (NBTBM4)] ceramic samples were prepared by using a solid-state method. X-ray diffraction analysis of the (1−x) NBTxBMO sample showed a rhombohedral structure and space group of R3c symmetry and confirmed the Rietveld refinement of the X-ray diffraction data. The micro-strain and the crystal sizes were calculated by using Williamson-Hall plots and experimentally verified with microstructural analyses. The in band-gap energy Eg varied from 3.28 to 3.17 eV for the (1− x) NBTxBMO ceramic samples. Furthermore, Raman spectra measured in the range from 100 to 1000 nm for the NBT-BMO powder samples showed new phonon modes and shifts to lower frequencies, which may be attributed to the incorporation of BMO into the NBT lattice.