Crystal chemistry and thermal expansion of Cd0.5Zr2(PO4)3 and Cd0.25Sr0.25Zr2(PO4)3 ceramics

Abstract Cd 0.5 Zr 2 (PO 4 ) 3 (CdZP) and the partially substituted phase Cd 0.25 Sr 0.25 Zr 2 (PO 4 ) 3 , prepared by the sol-gel route, belong to the NZP family. The structure of CdZP ( S.G.R3 ) has been established by the Rietveld method. The thermal behavior of CdZP, investigated by X-ray powder diffraction, is anisotropic, i.e., the structure expands along c axis and contracts along a axis. Dilatometric measurements and SEM micrographs of ceramics, sintered with 5% ZnO, show that CdSrZP presents the advantage to decrease microcracking, and then anisotropy, occurring during the heating cycle. The thermal expansion coefficient a bulk of the ceramic CdSrZP is very small (0.6 × 10 −6 °C −1 ).