Crystal structure solution and high-temperature thermal expansion in NaZr2(PO4)3-type materials

In this study, SrZr4P6O24 (SrO · 4ZrO2 · 3P2O5), CaZr4P6O24 (CaO · 4ZrO2 · 3P2O5), MgZr4P6O24 (MgO · 4ZrO2 · 3P2O5), NaTi2P3O12 [ ½ (Na2O · 4TiO2 · 3P2O5)], NaZr2P3O12 [ ½ (Na2O · 4ZrO2 · 3P2O5)], and related solid solutions were synthesized using the organic – inorganic steric entrapment method. The samples were characterized by in-situ high-temperature X-ray diffraction from 25 to 1500 ° C at the Advanced Photon Source and National Synchrotron Light Source II. The average linear thermal expansion of SrZr4P6O24 and CaZr4P6O24 was between − 1 × 10 − 6 per   ° C and 6 ×   10 − 6 per ° C from 25 to 1500 ° C. The crystal structures of the high-temperature polymorphs of CaZr4P6O24 and SrZr4P6O24 with R3c symmetry were solved by Fourier difference mapping and Rietveld refinement. This polymorph is present above ∼ 1250 ° C. This work measured thermal expansion coefficients to 1500 ° C for all samples and investigated the differences in thermal expansion mechanisms between polymorphs and between compositions.

Source: Acta Crystallographica Section B - March 22, 2024 Category: Chemistry Authors: Hulbert, B.S. Brodecki, J.E. Kriven, W.M. Tags: NZP-type materials CaZr4(PO4)6 SrZr4(PO4)6 phase transformation thermal expansion structure solution Fourier difference map powder diffraction research papers Source Type: research