A Ca substitution study of NaV2O4: High-pressure synthesis of the Na1?xCaxV2O4 solid solution |
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Authors: | Tamas Varga John F Mitchell Kazunari Yamaura David G Mandrus Jun Wang |
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Institution: | 1. Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439, USA;2. Condensed Matter Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA;3. Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA |
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Abstract: | Ambient pressure CaV2O4 and high-pressure NaV2O4 crystallize in the CaFe2O4 structure type containing double chains of edge-sharing VO6 octahedra. Recent measurements on NaV2O4 reveal low-dimensional metallicity and evidence of half-metallic ferromagnetism. In contrast, CaV2O4 is an antiferromagnetic insulator. To explore the evolution of these ground-state behaviors, we have prepared a series of Ca-doped NaV2O4 compounds with the formula Na1?xCaxV2O4 (x = 0–1) using high-pressure synthesis. Samples at the Na end (x = 0–0.07) show a broad antiferromagnetic transition in the 120–160 K range in accordance with earlier reports. Transport measurements show an insulator–metal transition at x ~ 0.2. Samples with higher Ca concentrations (x = 0.4–0.7) exhibit a metal–insulator transition around 150 K. The results for the Na1?xCaxV2O4 solid solution is discussed in comparison to existing studies at the Ca- and Na-rich ends. |
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