Synthesis and characterization of ((La1-xGdx)2Zr2O7; x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 1) nanoparticles for advanced TBCs

Multicomponent rare-earth oxide-doped zirconia-based thermal barrier coatings (TBCs) are attractive alternatives for yttria-stabilized zirconia (YSZ) in advanced TBC applications. In this study, a zirconia-based nanopowder doped by multiple rare-earth oxides ((La1-xGdx)2Zr2O7; x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 1) was synthesized using sol-gel and calcination method. The product was then characterized by X-ray diffraction (XRD), simultaneous thermal analysis (STA), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and dilatometric test. According to STA results, the proper calcination temperature of (La1-xGdx)2Zr2O7 nanopowders could be considered > 800 °C. The results indicated that Gd2Zr2O7 exhibits a defect fluorite-type structure, and with the incorporation of larger La3+, it transformed into an ordered pyrochlore-type structure. The microstructure and morphology of the product were studied by field emission scanning electron microscopy (FESEM), revealing the formation of (La1-xGdx)2Zr2O7 nanoparticles with the mean size below 100 nm. Also, the thermal expansion coefficient of (La1-xGdx)2Zr2O7 nanoparticles was determined 8–12.5 × 10−6 K−1 at 1000 °C.