Synthesis and characterization of negative thermal expansion of the Zr2(WO4)(PO4)2 system

In this study, Ti- and Mo-substituted Zr2(WO[Formula: see text](PO[Formula: see text] were synthesized using a conventional solid-state reaction technique. Coefficients of thermal expansions for samples were calculated by the results from the in situ high-temperature X-ray diffraction method. Doping with Ti[Formula: see text] reduces the voids occupied by the thermal vibration ellipsoid perpendicular to the bond axis. On the other hand, by doping Mo[Formula: see text], which has a smaller binding energy with oxygen atoms, thermal vibration in the direction of the bond axis is promoted. It is considered that the average linear thermal expansion coefficient became zero because the elliptical thermal vibration perpendicular to the coupling axis was suppressed by the synergistic effect of the co-doping of Ti and Mo.