Valence band spectra and doping based alterations in band gap and electric modulus of Nd₂NiMnO₆

Abstract

Here in this paper, extending our earlier study, we have investigated the electrical properties of Sr doped Nd2NiMnO6 through the study of electric modulus. Nd2NiMnO6 has been doped with Sr by replacing Nd and the doping has not induced any new phase as all the samples of Nd2-xSrxNiMnO6 (x=0.0, 0.1, 0.3) show monoclinic phase. Valence band spectra have been determined through X-ray photoemission spectroscopy and the absence of spectral density at Fermi energy EF for all the three samples indicates the insulating behavior with the sample having doping concentration x=0.1 being the highly insulating of all the samples. Modulus study has been carried out in order to investigate more about the electrical properties by studying the dependence of real and imaginary part of modulus on frequency and temperature. The variation of real and imaginary part of electric modulus with the concentration of dopant has also been observed. The modulus study reveals the relaxation phenomenon in all the three samples. Further, we have determined the band gap of three samples through UV-Visible spectroscopy and the variation in the value of band gap with changing concentration of dopant Sr is in accordance with the conductivity plots already discussed in our earlier studies.