Effect of Li + Ion Substitution on Structural and Dielectric Properties of Bi 0.5 Na 0.5- x Li x TiO 3 Nanoceramics

In this study, we fabricated Li + doped Bi 1/2 Na 1/2- x Li x TiO 3 [BNLT] ( x = 0.0, 0.025, 0.05, 0.075 and 0.1) nanoceramics by double sintered solid-state reaction method. The structural, optical, dielectric and ferroelectric properties of the ceramic samples have been investigated. X-ray diffraction results confirm that all the ceramics are pure phase perovskite with rhombohedral structure and R 3 c space group. The different bonds (Bi 3+ /Na + /Li + and Ti 4+ –O) related to vibrational modes have been studied by analyzing the Raman spectra. The observed optical band gaps were found to decrease from 3.37 to 3.31 eV as the Li + doping is increased. The dielectric permittivity ( ε′ ) and loss factor (tan δ ) reduces with a raise in the frequency whereas at elevated frequency both became constant. Dielectric plot show irregular trends with increasing Li + ion replacement. The ac conductivity is found to rise with a higher frequency. Modulus and complex impedance study point toward the continuation of equal grain and grain boundary assistance in BNLT ceramics. The P – E hysteresis loops verify the ferroelectric nature of all the ceramics.