Gadolinium zirconium oxide (Gd 2 Zr 2 O 7 ) films, a promising candidate for thermal barrier coatings and buffer layers in superconductors, are deposited on Al 2 O 3 substrate by using an RF-magnetron sputtering method for the study of thermal conductivity. Thermal conductivity is measured by both methods of time domain thermoreflectance and 3 omega methods, which can give rise to the difference in the heat penetration depth. Since phonon mean free path in Gd 2 Zr 2 O 7 is smaller than lattice constant due to oxygen vacancy, the film thickness variation in 100–500 nm does not affect thermal conductivity seriously unless interfacial thermal resistance is involved. The interfacial effect can be included or excluded in thermal conductivity depending on the heat penetration depth of heat waves. There is discrepancy between the experimental results of thermal conductivity obtained by the two methods, due to the effect of interfacial thermal resistance. The interfacial effect on thermal conductivity is verified through comparison of the two experimental results, and the Debye–Callaway modeling.
