Structural, Optical, and Dielectric Properties of Double Perovskite La2NiMnO6

Abstract

Double perovskite materials incorporating rare earth elements, such as La₂BB′O₆ (here B represents Ni and B′ denotes Mn), have been extensively investigated. In this study, La₂NiMnO₆ (LNMO) was synthesized by employing solid-state reaction approach. X-ray diffraction (XRD) analysis confirmed development of a monoclinic crystal structure with P2₁/n space group. Diffuse reflectance spectroscopy demonstrated strong reflectance and minimal absorbance in visible and near-infrared regions, indicating optical transparency. Direct optical band gap, estimated to be 2.96 eV using the Kubelka–Munk-transformed Tauc plot, highlights its potential for UV-filtering and optoelectronic applications. FTIR spectra exhibited pronounced antisymmetric stretching at ~ 556.78 cm⁻¹ and bending modes around 913.24 cm⁻¹, affirming the presence of Ni–O and Mn–O bonds within (Ni/Mn) O₆ octahedral network. Ferromagnetic transitions observed near 150 K and 280 K were attributed to B-site cation ordering. Dielectric studies over the 20 kHz–2 MHz range, modelled by the Maxwell–Wagner and Koops theories, revealed Debye relaxation behaviour and characteristic impedance trends.

Graphical Abstract