Alkali metal insertion and dielectric studies on anion excess fluorite related mixed oxide Bi<inf>2</inf>Te<inf>2</inf>W<inf>3</inf>O<inf>16</inf>

Alkali metals like Li and Na are inserted into the tunnels of anion excess fluorite related structure compound Bi2Te2W3O16 using n-butyllithium and NaN3, respectively without any perceptible change of crystal structure. The insertion process is not completely reversible. The alkali metal inserted phases have room temperature resistivity values three orders less than that of the parent phase. The parent phase Bi2Te2W3O16 shows anomalous increase in dielectric constant with temperature.