Preparation and Thermal Expansion of Calcium Iron Zirconium Phosphates with the NaZr2(PO4)(3) Structure

Ca0.5(1 + x)Zr2-x Fe (x) (PO4)(3) phosphates have been synthesized by a sol-gel process. The individual compounds and solid solutions obtained crystallize in the NaZr2(PO4)(3) structure (trigonal symmetry, sp. gr. R ). Using high-temperature X-ray diffraction, we have determined their thermal expansion parameters in the temperature range from 25 to 800A degrees C. With increasing x, the magnitudes of their linear thermal expansion coefficients and thermal expansion anisotropy decrease. Most of the synthesized phosphates can be rated as low-thermal-expansion compounds and can be regarded as materials capable of withstanding thermal stress..