Crystal structure, mechanical and thermophysical properties of Ca0.5Sr0.5Zr4-xSnxP6O24 ceramics

Abstract

Ca0.5Sr0.5Zr4-xSnxP6O24 (0 ≤ x ≤ 0.2) ceramics belonging to a new NZP family were prepared by coprecipitation, to determine the effect of Sn4+-substitution for Zr4+ on the crystal structure, mechanical and thermophysical properties of the ceramics. XRD patterns revealed that a single phase was formed for all compositions. Rietveld refinement was used to analyze the crystal structure and the lattice parameters exhibited a satisfactory structural convergence of R-factors. The substitution of Sn4+ for Zr4+ could effectively improve the sinterability, meanwhile, the flexural strength and Vickers hardness could reach to 60.2 MPa and 3.05 GPa, respectively. The thermal expansion varied from 1.72 to 2.78 × 10−6/oC with Sn4+-substitution increasing. Besides, the thermal conductivity of Ca0.5Sr0.5Zr3.8Sn0.2P6O24 (x = 0.2) reached a minimum value of 0.79 W m−1oC−1 at 1000 °C. The present investigation let provide that the Ca0.5Sr0.5Zr4-xSnxP6O24 ceramics with high mechanical strength and excellent thermophysical properties are promising candidate materials in high temperature applications.