The [Formula: see text] ceramics have excellent high-temperature phase stability and mechanical properties and show great potential for use as next-generation thermal barrier coating (TBC) materials. However, the thermophysical properties of [Formula: see text], especially [Formula: see text]-doped, were not clearly established. The [Formula: see text] ceramics doped with different contents of [Formula: see text] (0%, 2%, 4%, 6%, and 8%) by high-temperature solid-state reaction were studied in this paper. The phase structures and microstructures of the samples were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and EDS. The thermophysical properties of the samples including specific heat, thermal diffusivity, and thermal conductivity were measured systematically. The results show that [Formula: see text]-doped [Formula: see text] ceramics have a single monoclinic phase, and that [Formula: see text] ion doping does not change the crystal structure. The bandgap of 2% [Formula: see text]-doped [Formula: see text] ceramics was narrow (4.48 eV), indicating that heat is conducted by phonons in ceramics. The [Formula: see text] doped with 2% of [Formula: see text] had lower thermal conductivity [Formula: see text] at [Formula: see text] than [Formula: see text] [Formula: see text] at [Formula: see text]. This indicates that 2% [Formula: see text]-doped [Formula: see text] ceramics have the potential to be employed as TBCs in next-generation gas turbines.
