Thermal Expansion of Phosphates with the NaZr2(PO4)3 Structure Containing Lanthanides and Zirconium: R0.33Zr2(PO4)3 (R = Nd, Eu, Er) and Er0.33(1-x)Zr0.25xZr2(PO4)3

Phosphates R0.33Zr2(PO4)(3) (R = Nd, Eu, or Er) and Er0.33(1-x)Zr0.25Zr2(PO4)(3) (x = 0, 0.25, 0.5, 0.75, 1.0) of the NaZr2(PO4)(3) family have been synthesized and investigated by high-temperature X-ray diffraction. The crystallochemical approach is used to obtain compounds with expected small and controllable thermal-expansion parameters. Phosphates with close-to-zero thermal-expansion parameters, including those with low thermal-expansion anisotropy, have been obtained: Nd0.33Zr2(PO4)(3) with alpha(a) =-2.21 x 10(-6) A degrees D-1, alpha(c) = 0.81 x 10(-6) A degrees D-1, and Delta alpha = 3.02 x 10(-6) A degrees D-1 and Er0.08Zr0.19Zr2(PO4)(3) with alpha(a) =-1.86 x 10(-6) A degrees D-1, alpha(c) = 1.73 x 10(-6) A degrees D-1, and Delta alpha = 3.58 x 10(-6)degrees C-1.