Exploration of the low thermal conductivities of γ-Y2Si2O7, β-Y2Si2O7, β-Yb2Si2O7, and β-Lu2Si2O7 as novel environmental barrier coating candidates. Issue 11 (September 2016)

• Record Type: Journal Article
• Authors: Tian, Zhilin; Zheng, Liya; Li, Zhaojin; Li, Jialin; Wang, Jingyang
• Is Part Of: Journal of the European Ceramic Society. Volume 36:Issue 11(2016:)
• Page Start: 2813
• Page End: 2823
• Publication Date: 2016-09
• Subjects: Rare-earth silicates -- Environmental barrier coating -- Thermal conductivity; Ceramic materials -- Periodicals; Composite materials -- Periodicals; Matériaux céramiques -- Périodiques; Composites -- Périodiques; Ceramic materials; Composite materials; Periodicals; Electronic journals; 666.05
• DOI: 10.1016/j.jeurceramsoc.2016.04.022
• Languages: English
• ISSNs: 0955-2219

Abstract

Abstract: Thermal conductivities of γ-Y2 Si2 O7, β-Y2 Si2 O7, β-Yb2 Si2 O7, and β-Lu2 Si2 O7 were investigated by combined first-principles calculations and experimental evaluation. Theoretical calculation was used to predict the elastic properties, anisotropic minimum thermal conductivities, and temperature dependent lattice thermal conductivities. Experimentally, thermal conductivities of these disilicates were measured from room temperature to 1273 K. In addition, their experimental intrinsic lattice thermal conductivities were determined from the corrected thermal diffusivity data after removing the extrinsic contributions from phonon scattering by defects and thermal radiation. The experimental lattice thermal conductivities match well with the theoretical predictions. Furthermore, Raman spectra of the disilicates was measured and used to estimate the optical phonon relaxation time. The present results clearly disclose the specific material parameters that determine the low thermal conductivity of RE2 Si2 O7 and may provide guidelines for the optimal thermal conductivity of rare earth disilicates.