Effect of heavy mixing lithium with doping of manganese on structural, EPR and dielectric spectroscopic properties of Layered Na2Ti3O7

Abstract

Sintered ceramic samples of Na2Ti3O7 with 50 % (1.0 Molar Percentage of Li2CO3 i. e. 50 % Lithium) with different doping molar percentages MnO2 (0.0 < X<0.1) have been prepared through solid state reaction route. The microstructure, EPR, dielectric properties and ac conductivity of (NaLi)Ti3O7 with Mn [0.0 ≤ X≤0.1] have been investigated. The X-ray diffraction patterns of pure and doped layered ceramics suggest the crystals are orthorhombic in phase. The room temperature electron paramagnetic resonance spectra reveal that that for lower percentage of doping manganese ions occupies Ti 4+ site with oxidation state Mn3+, while higher percentage of manganese ions doping leads to oxidation state Mn2+ in interlayer mixed (Na Li) site. In both cases the charge compensation mechanism should operate to maintain the overall charge neutrality of the lattice. For all pure and doped layered ceramics, ferroelectric transition having high transition temperature has been identifying at 648 K. Manganese ion doping decreases dielectric loss and increases dielectric constant due to inhibition of domain wall motion. It is apparent that ionic conduction becomes difficult due to presence of more lithium ions with sodium ions in interlayer space which shrinking the wide space of interlayer channels.