An international team of researchers has successfully synthesized a thermodynamically stable compound of sodium and the noble gas helium, Na2He, which has a fluorite-type structure and is stable at high pressures. Their results were published this week in the journal Nature Chemistry. Microphotograph of the diamond anvil cell high-pressure cavity in reflected and transmitted light at 140 GPa after laser heating to > 1,500 degrees Kelvin. The sample,...
