Origin of the mixed alkali effect in silicate glass

Adding different types of atoms to silicate glass dramatically changes its properties, and scientists in Japan have found an atomic-level reason why. The manufacture of glass has evolved over many centuries, and scientists are still attempting to improve its properties. Common silicate glass is made from silicon and oxygen, but adding atoms such as either sodium or potassium can change its properties, for example massively decreasing its viscocity. Why such minor changes have such a large effect remains unclear. To better understand this so-called mixed alkali effect, Shinji Kohara from the National Institute for Materials Science, and colleagues combined state-of-the art diffraction techniques and numerical methods to construct atomic views of alkaline-doped glasses. This showed that the added atoms significantly reduce the size of the cavities found in silicate glass.