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Materials with low thermal conductivity are essential to providing thermal insulation to many technological systems, such as electronics, thermoelectrics and aerospace devices. Here, we report ultra-low thermal conductivity of two oxide materials. Sr 2 FeCoO 6−δ has a perovskite-type structure with oxygen vacancies. It shows a thermal conductivity of 0.5 W m −1 K −1 , which is lower than those reported for perovskite oxides. The incorporation of calcium to form Ca 2 FeCoO 6−δ , leads to a structural change and the formation of different coordination geometries around the transition metals. This structural transformation results in a remarkable enhancement of the thermal insulation properties, showing the ultra-low thermal conductivity of 0.05 W m −1 K −1 , which is one of the lowest values found among solid materials to date. A comparison to previously reported perovskite oxides, which show significantly inferior thermal insulation compared to our materials, points to the effect of oxygen-vacancies and their ordering on thermal conductivity.
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Comparative Thermal Insulation Nature of Ca 2 FeMnO 6−δ and Sr 2 FeMnO 6−δ
In this study, we investigate the utility of Ca2FeMnO6-δand Sr2FeMnO6-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. Ca2FeMnO6-δadopts a brownmillerite-type orthorhombic structure with ordered vacancy arrangement, while Sr2FeMnO6-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.
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- PAR ID:
- 10491329
- Publisher / Repository:
- The Electrochemical Society
- Date Published:
- Journal Name:
- ECS Advances
- Volume:
- 3
- Issue:
- 1
- ISSN:
- 2754-2734
- Format(s):
- Medium: X Size: Article No. 014001
- Size(s):
- Article No. 014001
- Sponsoring Org:
- National Science Foundation
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