Thermophysical properties in the YNbO${}_4$-ZrO${}_2$ pseudo-binary phase diagram with YNbO${}_4$-rich end

The matrix YNbO${}_4$ ceramics with a series of content of ZrO${}_2$ is synthesized by the conventional solid-state reaction method in the present article. Owing to the similarity in structure, the YNbO${}_4$ 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 ZrO${}_2$ that exists in the YNbO${}_4$ 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 YNbO${}_4$-ZrO${}_2$ 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. (© 2022 Wiley‐VCH GmbH)