A New, Low‐Temperature Polymorph of Ó‐SiAlON

A new phase in the Si-Al-O-N system has been identified, following syntheses based on the nitridation of silicon/clay mixtures at low temperatures (<1350°C). The structure of the new phase was determined using a combination of diffraction and high-resolution imaging techniques, and this new phase possessed the same sheet structure as O-SiAlON (Si2−xAlxO1+xN2−x) but with a different stacking arrangement. It is considered to be a low-temperature polymorph of O-SiAlON and transforms to conventional O-SiAlON at temperatures greater than ∼1350°C.