Oxygen Vacancy in Magnéli Phases and Its Effect on Thermoelectric Performances
Magnéli phases exhibit significant potential for applications in electronic materials in energy conversion due to their high electrical conductivity and excellent thermal stability. In this study, single-phase Ti<sub>n</sub>O<sub>2n−1</sub> (<i>n</i> = 4, 5, 6) bu...
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2025-04-01
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| author | Zhou Guan Chuangshi Feng Hongquan Song Lingxu Yang Xin Wang Huijun Liu Jiawei Zhang Fanqian Wei Xin Yuan Hengyong Yang Yu Tang Fuxiang Zhang |
| author_facet | Zhou Guan Chuangshi Feng Hongquan Song Lingxu Yang Xin Wang Huijun Liu Jiawei Zhang Fanqian Wei Xin Yuan Hengyong Yang Yu Tang Fuxiang Zhang |
| author_sort | Zhou Guan |
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| description | Magnéli phases exhibit significant potential for applications in electronic materials in energy conversion due to their high electrical conductivity and excellent thermal stability. In this study, single-phase Ti<sub>n</sub>O<sub>2n−1</sub> (<i>n</i> = 4, 5, 6) bulk materials were successfully prepared by a combination of the carbothermal reduction of nano-sized rutile TiO<sub>2</sub> and hot-press sintering methods. The relationships between the phase evolution, microstructural features, and thermoelectric performance were investigated systematically. Synchrotron X-ray diffraction (SXRD) and scanning electron microscopy (SEM) analyses revealed that the Ti<sub>4</sub>O<sub>7</sub> and Ti<sub>5</sub>O<sub>9</sub> materials had single-phase structures with high densities (relative density > 97%) and no obvious grain boundary holes or microcracks. We tested the thermoelectric properties of the Magnéli phases in the temperature range of 300–1100 K. The Magnéli phases exhibited a significant temperature dependence, with peak zT values of 0.17, 0.18, and 0.14 for Ti<sub>4</sub>O<sub>7</sub>, Ti<sub>5</sub>O<sub>9</sub>, and Ti<sub>6</sub>O<sub>11</sub>, respectively, at 1100 K. This variation in thermoelectric performance was mainly attributed to the synergistic effect of the oxygen vacancy concentration and the shear surface density on the carrier concentration and lattice thermal conductivity. Furthermore, the Fermi energy levels and electronic thermal conductivity of the Magnéli phases were calculated using the single parabolic band (SPB) model. |
| format | Article |
| id | doaj-art-329452c615014b45a74565b2b6050b01 |
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| issn | 2079-4991 |
| language | English |
| publishDate | 2025-04-01 |
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| series | Nanomaterials |
| spelling | doaj-art-329452c615014b45a74565b2b6050b012025-08-20T02:59:15ZengMDPI AGNanomaterials2079-49912025-04-0115968410.3390/nano15090684Oxygen Vacancy in Magnéli Phases and Its Effect on Thermoelectric PerformancesZhou Guan0Chuangshi Feng1Hongquan Song2Lingxu Yang3Xin Wang4Huijun Liu5Jiawei Zhang6Fanqian Wei7Xin Yuan8Hengyong Yang9Yu Tang10Fuxiang Zhang11Songshan Lake Materials Laboratory, Dongguan 523808, ChinaSongshan Lake Materials Laboratory, Dongguan 523808, ChinaCollege of Physics and Telecommunication Engineering, Zhoukou Normal University, Zhoukou 466001, ChinaSchool of Ocean Engineering, Guangzhou Maritime University, Guangzhou 510330, ChinaSongshan Lake Materials Laboratory, Dongguan 523808, ChinaSongshan Lake Materials Laboratory, Dongguan 523808, ChinaSongshan Lake Materials Laboratory, Dongguan 523808, ChinaSongshan Lake Materials Laboratory, Dongguan 523808, ChinaSongshan Lake Materials Laboratory, Dongguan 523808, ChinaSongshan Lake Materials Laboratory, Dongguan 523808, ChinaSongshan Lake Materials Laboratory, Dongguan 523808, ChinaSongshan Lake Materials Laboratory, Dongguan 523808, ChinaMagnéli phases exhibit significant potential for applications in electronic materials in energy conversion due to their high electrical conductivity and excellent thermal stability. In this study, single-phase Ti<sub>n</sub>O<sub>2n−1</sub> (<i>n</i> = 4, 5, 6) bulk materials were successfully prepared by a combination of the carbothermal reduction of nano-sized rutile TiO<sub>2</sub> and hot-press sintering methods. The relationships between the phase evolution, microstructural features, and thermoelectric performance were investigated systematically. Synchrotron X-ray diffraction (SXRD) and scanning electron microscopy (SEM) analyses revealed that the Ti<sub>4</sub>O<sub>7</sub> and Ti<sub>5</sub>O<sub>9</sub> materials had single-phase structures with high densities (relative density > 97%) and no obvious grain boundary holes or microcracks. We tested the thermoelectric properties of the Magnéli phases in the temperature range of 300–1100 K. The Magnéli phases exhibited a significant temperature dependence, with peak zT values of 0.17, 0.18, and 0.14 for Ti<sub>4</sub>O<sub>7</sub>, Ti<sub>5</sub>O<sub>9</sub>, and Ti<sub>6</sub>O<sub>11</sub>, respectively, at 1100 K. This variation in thermoelectric performance was mainly attributed to the synergistic effect of the oxygen vacancy concentration and the shear surface density on the carrier concentration and lattice thermal conductivity. Furthermore, the Fermi energy levels and electronic thermal conductivity of the Magnéli phases were calculated using the single parabolic band (SPB) model.https://www.mdpi.com/2079-4991/15/9/684Magnéli phaseoxygen vacancythermoelectric performancesingle parabolic band |
| spellingShingle | Zhou Guan Chuangshi Feng Hongquan Song Lingxu Yang Xin Wang Huijun Liu Jiawei Zhang Fanqian Wei Xin Yuan Hengyong Yang Yu Tang Fuxiang Zhang Oxygen Vacancy in Magnéli Phases and Its Effect on Thermoelectric Performances Nanomaterials Magnéli phase oxygen vacancy thermoelectric performance single parabolic band |
| title | Oxygen Vacancy in Magnéli Phases and Its Effect on Thermoelectric Performances |
| title_full | Oxygen Vacancy in Magnéli Phases and Its Effect on Thermoelectric Performances |
| title_fullStr | Oxygen Vacancy in Magnéli Phases and Its Effect on Thermoelectric Performances |
| title_full_unstemmed | Oxygen Vacancy in Magnéli Phases and Its Effect on Thermoelectric Performances |
| title_short | Oxygen Vacancy in Magnéli Phases and Its Effect on Thermoelectric Performances |
| title_sort | oxygen vacancy in magneli phases and its effect on thermoelectric performances |
| topic | Magnéli phase oxygen vacancy thermoelectric performance single parabolic band |
| url | https://www.mdpi.com/2079-4991/15/9/684 |
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