Continuous tailoring thermal expansion from giant negative to positive in Ni2P2O7-based materials

Control of thermal expansion is of great fundamental and technological significance for functional materials. Here, we have achieved the thermal expansion controllable from giant negative, zero to positive in Ni2P2O7–based materials through doping Mn. A joint study of XRD and Raman was conducted to reveal negative thermal expansion originates in the change of phase proportional. This work also provided new insight into to improve negative thermal expansion in phase transition type materials.