Effects of Y2O3 addition on the phase evolution and thermophysical properties of lanthanum zirconate

Lanthanum zirconate (La2Zr2O7, LZ) powders with the addition of various Y2O3 contents for potential thermal barrier coatings (TBCs) application were synthesized by solid-state reaction. The structure evolution, sintering-resistance and thermophysical properties of the synthesized powders and sintered ceramics were systematically studied. X-ray diffraction (XRD) results indicate that LZ containing 3–12 wt.% Y2O3 mainly keeps a pyrochlore-type structure, and two new phases of LaYO3 and Y0.18Zr0.82O1.91 are also detected. Raman spectra confirm that the higher the Y2O3 content, the easier is the formation of LaYO3. With the increase of Y2O3 content, the linear thermal expansion coefficients (TEC) of different La2O3–ZrO2–Y2O3 ceramics may gradually decrease. Additionally, LZ ceramics doped with 3 wt.% Y2O3 have the lowest relative density and the highest sintering-resistance among all samples, implying that it is the best candidate for TBCs among those samples in this investigation.