Investigation of electrical properties and conduction mechanism using CBH model of Ba0.97La0.02Ti1−xNb4x/5O3 (x = 0.00 and 0.02) compounds

Abstract

Lead-free Ba0.97La0.02Ti1−xNb4x/5O3 (abbreviated as BLT and BLT0.98Nb0.016) ceramics were grown using the molten-salt method with filtration as well as evaporation technique. A correlation investigation between the morphological, structural, and electrical properties of the system was carried out using impedance spectroscopy at various frequencies (40–106 Hz) and temperatures (500–600 K). In the present work, average grain size estimated from the microstructure was ~ 2700 nm. Phase composition was established by the Rietveld refinement, which confirms that our compounds have a single phased nature and crystal structure. They have a tetragonal Perovskite structure with a P4/mmm space group, without any secondary phases. Z′ and Z″ values of impedance decreased with increasing Nb concentration. The EIS data displayed an approximately perfect semi-circle at high temperature in the complex plane plot as well as a practically ideal non-Debye peak shape in the spectroscopic plot. The electrical conductivity decreased with increasing niobium amount. The frequency dependence of conductivity plot has been found to obey the universal Jonscher power law. The correlated barrier hoping was established to be the most suitable theoretical model to elucidate the conduction process. These results could help improve the electrical properties of Ba0.97La0.02Ti1−xNb4x/5O3 compounds and understand the relationship between the structure and the electrical properties.