scientists at tokyo institute of technology (tokyo tech) ; nagoya institute of technology; national institute of technology, niihama college; neutron science and technology center, the comprehensive research organization for science and society (cross); and japan atomic energy agency have shown the overbonding of channel oxygens in la-rich apatite-type lanthanum silicates, rather than the presence of the interstitial oxygens, to be responsible for the high oxide-ion conductivity. this concept of `high oxide-ion conductivity by overbonding` opens the door for designing better ion conductors, which could be useful in energy conversion and environmental protection.solid oxide electrolytes have been extensively studied due to their wide range of applications in solid oxide fuel cells (sofcs), oxygen membranes, catalysts, and gas sensors. electrolytes with high oxide-ion conductivity at temperatures below 600 °c are required to decrease the operation temperature of sofcs. professor susumu nakayama at national institute of technology, niihama college has discovered in 1995 the extremely high oxide-ion conductivity in the intermediate temperature range below 600°c, which has encouraged many researchers to study the structural origin of this phenomenon.it was believed that the high oxide-ion conductivity of apatite-type materials is due to interstitial oxygens. however, in this novel study, professor masatomo yashima, dr. kotaro fujii at tokyo institute of technology (tokyo tech)...