Hydrous compound promises industrial heat savings

The research, a collaboration between scientists at Tohoku University's Institute for Materials Research and Tokyo-based Rigaku Corporation, is detailed in Nature Communications.

The researchers used a layered manganese oxide mineral containing potassium ions and crystal water. The mineral is said to be quite similar in composition to birnessite, which is commonly found on the Earth's surface. The team fabricated their compound in the form of an insoluble black powder and then examined its crystal structure using an X-ray diffractometer and a transmission electron microscope. They then examined how the compound's structure changed when heated or cooled, and how much and how quickly heat energy was stored and released.

Heating the material up to 200︎^oC dehydrated it by giving its stored water molecules the energy needed to be released into the surrounding atmosphere. When the dehydrated material was then cooled below 120︎^oC in a dry container and then exposed to humid air, it absorbed water molecules and released its stored heat.