A transparent electrical conductor has been produced from an insulating oxide by a team at the Tokyo Institute of Technology in Yokohama and the Japan Science and Technology Corp. in Kawasaki. The method incorporates hydrogen ions into the crystal lattice structure of the oxide by heating it in a hydrogen-rich atmosphere. Exposure to UV radiation from a xenon lamp makes the conductivity permanent.The photoactivated material exhibits approximately 0.3 S/cm-1 of conductivity at room temperature and becomes 1 percent more absorptive per 200 nm of thickness. The researchers report in the Oct. 3 issue of Nature that the UV radiation may promote conductivity by transforming the hydrogen ions into sets of neutral H2 molecules and migrating electrons. They believe that similar methods could be applied to main-group metal oxides for applications such as invisible circuits and high-density optical memory systems.