Abstract
The Magnéli phase V6O11 was synthesized in gram amounts from a powder mixture of V6O11/V7O13 and vanadium metal, using the spark plasma sintering (SPS) technique. Its structure was determined with synchrotron X-ray powder diffraction data from a phase-pure sample synthesized by conventional solid-state synthesis. A special feature of Magnéli-type oxides is a combination of crystallographic shear and intrinsic disorder that leads to relatively low lattice thermal conductivities. SPS prepared V6O11 has a relatively low thermal conductivity of κ = 2.72 ± 0.06 W (m K)-1 while being a n-type conductor with an electrical conductivity of σ = 0.039 ± 0.005 (μΩ m)-1, a Seebeck coefficient of α = -(35 ± 2) μV K-1, which leads to a power factor of PF = 4.9 ± 0.8 × 10-5W (m K2)-1 at ∼600 K. Advances in the application of Magnéli phases are mostly hindered by synthetic and processing challenges, especially when metastable and nanostructured materials such as V6O11 are involved. This study gives insight into the complications of SPS-assisted synthesis of complex oxide materials, provides new information about the thermal and electrical properties of vanadium oxides at high temperatures, and supports the concept of reducing the thermal conductivity of materials with structural building blocks such as crystallographic shear (CS) planes.
Original language | English (US) |
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Pages (from-to) | 1259-1268 |
Number of pages | 10 |
Journal | Inorganic Chemistry |
Volume | 57 |
Issue number | 3 |
DOIs | |
State | Published - Jan 11 2018 |
Bibliographical note
KAUST Repository Item: Exported on 2020-10-01Acknowledgements: This research was funded by the Deutsche Forschungsgemeinschaft (DFG) through the priority program SPP1959 Manipulation of Matter Controlled by Electric and Magnetic Fields: Towards Novel Synthesis and Processing Routes of Inorganic Materials. Use of the Advanced Photon Source at Argonne National Laboratory was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. We thank all the contributors of this project for their well appreciated assistance. Special thanks go out to the staff of Argonne National Laboratory at Beamline 11-BM, who provided us with insightful high-resolution PXRD data from synchrotron measurements. We thank R. Jung-Pothmann and Jakob Drebert for technical support with PXRD and XPS analysis, J. Tapp and Prof. Dr. A. Möller for help with the thermal analysis, and M. Lange for assistance with HR-TEM measurements.