Dielectric, electrochemical and magnetic properties of the hydrothermally synthesized double perovskite La2NiMnO6 for energy storage applications

Double perovskite materials are greatly appealing because of their multiferroic properties. Among such materials, double perovskite with rare earth metals are widely studied by researchers. Presently, the double perovskite La2NiMnO6 (LNMO) samples are synthesized using the hydrothermal method by varying the concentration of the solvent (NaOH). The Powder X-ray diffraction analysis confirmed the formation of monoclinic structure with the P21/n space group for prepared LNMO samples. The SEM image of the prepared samples revealed a cube-like structure. The impedance, dielectric, AC conductivity and modulus are studied in a wide frequency range from 100 Hz to 5 MHz to analyse the electrical and microstructure properties of the synthesized LNMO samples. The presence of a non- Debye type of relaxation peak is confirmed by impedance, dielectric and modulus studies. The effect of grains and grain boundaries are analysed by the Nyquist plot and the polarization of the materials are explained by the Maxwell-Wagner interfacial polarization model and Koop's theory. Using a three electrode system, the electrochemical behaviour of prepared LNMO samples are studied in various concentration of electrolyte (KOH) at different scan rates and found to have a pseudocapacitive nature. The highest specific capacitance value for LNMO10 is 44.60 F/g, LNMO20 is 50.14 F/g and LNMO30 is 25.81 F/g at a scan rate of 10 mV/s for 3 M KOH. The room temperature magnetic behaviour of synthesized LNMO samples analysed by Vibrating Sample Magnetometer paves way for magnetic storage applications.