Electrical properties of nano Li₂TiO₃ for fusion reactors

In the development of tritium breeding blankets for fusion reactor, lithium based ceramic such as lithium orthosilicate (Li₄SiO₄), lithium titanate (Li₂TiO₃), lithium zirconate (Li₂ZrO₃), and lithium oxide (Li₂O) for breeding blankets. Among them Lithium titanate (LT) is one of the most promising tritium breeding materials due to their reasonable lithium atom density, low activation, good compatibility with structural materials, excellent tritium release performance and chemical stability. Electrical properties may reflect some characteristic features, hence analysis of electrical charge transport in small grained Li₂TiO₃ ceramics, as envisaged for tritium breeding, may contribute to gain information of certain high energy ball-milling process. The main attribute of current study analyzes the electrical conductivity behavior of Li₂TiO₃ ceramics. The 10h milled powder of Li₂TiO₃ by High energy ball milling (HEBM) calcined at 700 °C for 2h. The calcinied powder was pressed uniaxially with 3wt. % PVA (polyvinyl alcohol) solution added as binder. The rectangular disk samples of diameter 12.7mm and thickness 12mm was made by hydraulic press with 400 Mpa pressure. The samples were sintered at 700 °C, 800 °C, 900 °C and 1000 °C 2h in conventional sintering. Silver contacts were made on the opposite disc faces and heated at 700 °C for 15 minutes with a heating 5 °C per minute for electrical measurement. It was found that microwave sintered samples shows higher thermal conductivity then conventional sintered one. The Ea value decreases with increase in frequency, due to the increase in ionic conductivity. The ionic conductivity is a combination of both macroscopic and microscopic conduction, which indirectly depend on the bulk R_b and grain boundary R_gb resistance. At high temperature only single semicircle could be found, using high frequency data, indicate dominant behavior of grain. The value of activation energy (0.238eV) and conductivity range (10^-3 to 10^-4 S/cm) says that material is a semiconductor. (author)