Structural and electrical properties of high-energy ball-milled NASICON type Li1.3Ti1.7Al0.3(PO4)2.9(VO4)0.1 ceramics

Nano-crystallites of Li1.3Ti1.7Al0.3(PO4)2.9(VO4)0.1 NASICON type material are prepared by means of solid-state reaction of a stoichiometric mixture after milling it for 22 and 55 h. The milling reduces the average crystallite size of the ceramic to 80 and 60 nm, respectively. Mechanical milling changes structural parameters and the strain induced at the grain-boundaries plays a major role in improving electrical conductivity. An order of magnitude increase in electrical conductivity is observed in the material milled for 55 h compared to the unmilled material, which is also reflected in permittivity loss. Modulus and permittivity representations substantiate the constriction effect of grain-boundaries observed in the complex impedance representation.

Research highlights► In the present study, high-energy ball-milling technique is used to decrease the average crystallite size to nano-range. ► The reduction in crystallite size increases the volume fraction of grain-boundaries; which are easier paths for ion diffusion. ► An order of magnitude increase in electrical conductivity is observed in the material milled for 55 h compared to the unmilled material, which is also reflected in permittivity loss. ► Present work clearly demonstrated and explained that grain-boundaries play a major role in ion diffusion in nano-materials.