Glass‐Like Thermal Conductivity of (010)‐Textured Lanthanum‐Doped Strontium Niobate Synthesized with Wet Chemical Deposition

We have measured the cross‐plane thermal conductivity (κ) of (010)‐textured, undoped, and lanthanum‐doped strontium niobate (Sr_2?xLa_xNb₂O_7?δ) thin films via time‐domain thermoreflectance. The thin films were deposited on (001)‐oriented SrTiO₃ substrates via the highly‐scalable technique of chemical solution deposition. We find that both film thickness and lanthanum doping have little effect on κ, suggesting that there is a more dominant phonon scattering mechanism present in the system; namely the weak interlayer‐bonding along the b‐axis in the Sr₂Nb₂O₇ parent structure. Furthermore, we compare our experimental results with two variations of the minimum‐limit model for κ and discuss the nature of transport in material systems with weakly‐bonded layers. The low cross‐plane κ of these scalably‐fabricated films is comparable to that of similarly layered niobate structures grown epitaxially.