Structural and Electrochemical Properties of Type VIII Ba 8 Ga 16−δ Sn 30+δ Clathrate (δ ≈ 1) during Lithiation

Dopilka, Andrew; Childs, Amanda; Ovchinnikov, Alexander  (ORCID:0000000205374234); Zhao, Ran; Bobev, Svilen  (ORCID:0000000207804787); Peng, Xihong; Chan, Candace K.  (ORCID:0000000343294865)

doi:10.1021/acsami.1c07240

In this study, we investigate the utility of Ca₂FeMnO_6-δand Sr₂FeMnO_6-δas materials with low thermal conductivity, finding potential applications in thermoelectrics, electronics, solar devices, and gas turbines for land and aerospace use. These compounds, characterized as oxygen-deficient perovskites, feature distinct vacancy arrangements. Ca₂FeMnO_6-δadopts a brownmillerite-type orthorhombic structure with ordered vacancy arrangement, while Sr₂FeMnO_6-δadopts a perovskite cubic structure with disordered vacancy distribution. Notably, both compounds exhibit remarkably low thermal conductivity, measuring below 0.50 Wm⁻¹K⁻¹. This places them among the materials with the lowest thermal conductivity reported for perovskites. The observed low thermal conductivity is attributed to oxygen vacancies and phonon scattering. Interestingly as SEM images show the smaller grain size, our findings suggest that creating vacancies and lowering the grain size or increasing the grain boundaries play a crucial role in achieving such low thermal conductivity values. This characteristic enhances the potential of these materials for applications where efficient heat dissipation, safety, and equipment longevity are paramount.

More Like this