Microstructure and thermal properties of RETaO4 (RE = Nd, Eu, Gd, Dy, Er, Yb, Lu) as promising thermal barrier coating materials

The RETaO4 ceramics with low-thermal conductivity were fabricated using a solid-state reaction. The phase composition and microstructures of high-temperature RETaO4 (RE = Nd, Eu, Gd, Dy, Er, Yb, Lu) ceramics were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and Raman spectroscopy. The RETaO4 ceramics had lower thermal conductivity (138 to 1.94 W.m(-1).K-1 at 800 degrees C) than 7-8YSZ (2.37 and 2.47 W.m(-1).K-1 at 800 degrees C, respectively). The porosity significantly affected the thermal conductivity of RETaO4 ceramics. The RETaO4 ceramics also had lower Vickers hardness than 8YSZ, which suggests that RETaO4 has better fracture toughness and thermal tolerance. (C) 2016 Acta Materialia Inc Published by Elsevier Ltd. All rights reserved.