Raman spectroscopy and dielectric properties of nanoceramic NdFeO3

The nanoceramic NdFeO3 is synthesized by the sol–gel citrate method. The Rietveld refinement of X-ray diffraction pattern at room temperature (30 °C) shows the orthorhombic Pnma phase with lattice parameters a = 5.576 Å, b = 7.756 Å, c = 5.447 Å. Nano-sized crystallites of NdFeO3 ranging from 45 to 75 nm have been verified by the transmission electron microscope image. The room temperature Raman spectrum is fitted with the sum of 18 Lorentzian peaks. Eigen frequencies of vibrational modes are calculated using density functional theory under generalized gradient approximation and compared with experimental results. Dielectric spectroscopy study of NdFeO3 has been performed in the frequency range from 50 Hz to 1 MHz and in the temperature range from 50 °C to 240 °C. The frequency dependence of real and imaginary parts of dielectric permittivity is analyzed using Cole–Cole equation. The frequency dependent conductivity spectra follow the power law.