  We investigated systematic evolutions of structural and electronic properties
of LixWO3 films, induced by Li-ion electrochemical reactions.
Chronoamperometric Li-ion intercalation could control the amount of Li content
up to x ~ 0.5. The resistivity abruptly decreased with increasing x and the
films underwent an insulator to metal transition (IMT) within a range of 0.2 <
x < 0.24, which was consistent with IMT of cubic NaxWO3. The X-ray diffraction
analyses revealed the coexistence of tetragonal and cubic phases across IMT,
suggesting that the alkaline-ion content was a primary factor for metallic
conductivity in the ReO3-type WO3 system.
