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.