Crystal Structure Solution and High Temperature Thermal Expansions of NaZr2(PO4)3-type Materials

The NaZr₂P₃O₁₂ (NZP) family of materials have shown low and tailorable thermal expansion properties. This dataset includes SrZr₄P₆O₂₄, CaZr₄P₆O₂₄, NaTi₂P₃O₁₂, NaZr₂P₃O₁₂, MgZr₄P₆O₂₄, and related solid solutions. These materials were synthesized using the organic-inorganic steric entrapment method. The samples were characterized with in-situ high-temperature x-ray diffraction at the Advanced Photon Source and National Synchrotron Light Source II from 25 to 1500 ℃. The average linear thermal expansion of  SrZr₄P₆O₂₄ and CaZr₄P₆O₂₄ was between -1 x10^-6/℃ and 6 x10^-6/℃ from 25 to 1500 ℃. High temperature polymorphs of CaZr₄P₆O₂₄ and SrZr₄P₆O₂₄ were solved by Fourier difference mapping and Rietveld refinement. This polymorph is present above about 1250 ℃. This work measured thermal expansion coefficients to 1500 ℃ for all samples and investigated the differences in thermal expansion mechanisms between polymorphs and between compositions.