Ice β-XV – a novel ice polymorph

Water molecules can form different hydrogen-bonded networks, a property known as ice polymorphism. So far 18 different networks have been characterized using neutron diffraction on D2O samples. In our recent experiments we have discovered a novel ice polymorph, called ice β-XV (Gasser et al., Chem. Sci. 9 (2018)) 4224). It is a daughter polymorph to ice VI, and a sister polymorph to ice XV - it shares the same type of oxygen network with them. Refinement of its crystal structure has so far been hampered because an adverse isotope effect has hindered access to D2O ice β-XV. In our very recent work we found a route to the D2O form, allowing us to refine its crystal structure using the HRPD instrument. Upon heating ice β-XV experiences an order-to-order transition in its network of H atoms. This is the first of its kind known in ice physics and will be studied in detail on HRPD by us.