Structural, electrical and dielectric properties of nanocrystalline LiMgBO3 particles synthesized by Pechini process

摘要

Nanocrystalline lithium magnesium borate (LiMgBO3) powders were synthesized by a Pechini process. Thermal behavior of the polymeric intermediate of LiMgBO3 sample was studied by TG-DTA. Structure and the local structural coordination of the as-prepared and calcined polymeric intermediate at 750 degrees C of LiMgBO3 sample were investigated by FT-IR and Li-7 & B-11 magic angle spinning - nuclear magnetic resonance (MAS-NMR) measurements respectively. XRD results confirm the formation of the pure nanocrystalline monoclinic phase of the LiMgBO3 sample prepared at 750 degrees C. The BET surface area of the calcined polymeric intermediate of LiMgBO3 sample is found to be 60.48 m(2)g(-1). The observed SEM micrographs of the LiMgBO3 sample showed the formation of agglomerated sheet-like morphology particles and the existence of Mg and O elements in LiMgBO3 are confirmed from the SEM-EDX spectral result. The band gap energy of LiMgBO3 sample is evaluated and it was found to be 3.64 eV. From the analysis of the measured impedance data, at different frequencies and temperatures, the evaluated electrical conductivity of LiMgBO3 sample was found to be 9.706 x 10(-5) S cm(-1) at 200 degrees C. From the temperature dependence of conductivity (log sigma T vs. 1000/T) plot of the LiMgBO3 sample, the evaluated activation energy (E-a) for the migration of the charge carrier was found to be 0.62 eV. The measured impedance data and the LiMgBO3 sample pellet dimensions were used for calculating AC conductivity (sigma(ac)), dielectric (epsilon', epsilon '', tan delta), electric modulus (M' and M '') data and were analyzed to find out the electrical and dielectric properties of the LiMgBO3 sample. (C) 2017 Elsevier B.V. All rights reserved.