Structural, transport and collosal dielectric properties of A-site substituted La2NiO4

Abstract

A-site substituted nickelates of the type La2NiO4, La2-x Yx-y BayNiO4 (x = 0.1, y = 0.0, 0.05) prepared via solid state reaction route are reported. X-ray diffraction (XRD) data analysis confirms the type of phase and structure of synthesized samples. All the samples were found to have crystallized into the tetragonal structure (I4/mmm). The XRD results were further verified using Rietveld refinement technique and tetragonal structure with space group (I4/mmm) was confirmed for all the prepared samples under investigation. The single phased tetragonal lattice structure formation was also confirmed from Raman scattering spectroscopy via stretching modes of vibration displayed by the prepared nickelates around 440 cm−1 and 220 cm−1. The elemental composition was verified using EDAX technique while FESEM images revealed the porous nature and heavy agglomeration. The dielectric studies confirmed the collosal dielectric constant with lowered loss values in the frequency range of 105–106 Hz with retained dielectric constant in the range of 103–104 at 106 Hz. The low temperature four-probe dc resistivity measurement revealed the samples are semiconducting in nature.