Thermophysical Properties in the YNbO4-ZrO2 Pseudo-Binary Phase Diagram with YNbO4-Rich End

The matrix YNbO4 ceramics with a series of content of ZrO2 is synthesized by the conventional solid-state reaction method in the present article. Owing to the similarity in structure, the YNbO4 parent lattice is capable of solubilizing a large number of Zr atoms until its content exceeds 30 mol%. Lattice distortion introduced by the dopant leads to the shift of X-Ray diffraction (XRD) and the increase of full width at half maximum (FWHM) in the Raman-active peak. The results of the scanning electron microscope and energy-dispersive spectroscopy reveal that the ZrO2 that exists in the YNbO4 matrix as a second phase can significantly enhance polycrystalline sintering resistance, presenting minimum grain size under the same sintering condition. The results of thermophysical properties indicate that the investigated compositions in the YNbO4-ZrO2 pseudo-binary phase show lower thermal diffusivity and thermal conductivity than that of both pure phases. The minimum thermal conductivity is 1.5 W m(-1) K-1, which is lower than that of 8YSZ. Furthermore, its heat transfer obeys phonon to phonon and phonon to defect scattering mechanisms.