Enhanced densification and thermoelectric properties of Ca3Co4O9 ceramics fabricated by solid-state combustion and hot-pressing

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dc.contributor.authorThatawong, Bhoowadol
dc.contributor.authorSriondee, Manlika
dc.contributor.authorChongsatan, Wistsarut
dc.contributor.authorPalaporn, Dulyawich
dc.contributor.authorPinitsoontorn, Supree
dc.contributor.authorRittidech, Aurawan
dc.contributor.authorRattanachata, Arunothai
dc.contributor.authorSuriwong, Tawat
dc.contributor.authorVittayakorn, Naratip
dc.contributor.authorBongkarn, Theerachai
dc.date.accessioned2026-08-06T10:56:26Z
dc.date.available2026-08-06T10:56:26Z
dc.date.issued2026-11-15
dc.description.abstractThe Ca<inf>3</inf>Co<inf>4</inf>O<inf>9</inf> powders were synthesized by the solid-state combustion method and then calcined at 775-875 °C for 6 h. The combination of combustion-derived fine powders and hot pressing was adopted to improve the densification and thermoelectric (TE) performance of Ca<inf>3</inf>Co<inf>4</inf>O<inf>9</inf> ceramics. Dense Ca<inf>3</inf>Co<inf>4</inf>O<inf>9</inf> ceramics were subsequently fabricated by hot-pressing to investigate the influence of hot-pressing temperature (800-950 °C, 2 h) on phase formation, microstructure, electrical, and TE properties. The Ca<inf>3</inf>Co<inf>4</inf>O<inf>9</inf> powder was obtained after calcination at 800 °C for 6 h and exhibited an average particle size of 0.55 μm. XRD analysis confirmed that Ca<inf>3</inf>Co<inf>4</inf>O<inf>9</inf> was the predominant phase in all hot-pressed samples. XPS analysis further confirmed the presence of oxygen vacancy (V<inf>O</inf><sup>++</sup>)-related defects and mixed-valence cobalt species. FESEM observations revealed a dense microstructure composed of plate-like grains with an average grain size ranging from 0.61 to 0.96 μm. The bulk density ranged from 4.31 to 4.46 g/cm<sup>3</sup>, indicating dense ceramics. The electrical resistivity (ρ) decreased with increasing measured temperature for all samples. Among all samples, the ceramic hot-pressed at 900 °C exhibited the lowest ρ at 600 °C. The Seebeck coefficient (S) significantly increased from 150 μV/K to 223 μV/K, while the thermal conductivity (κ) decreased with increasing temperature. Due to the favorable combination of low ρ and high S, the sample hot-pressed at 900 °C achieved the highest power factor (PF) and a maximum dimensionless figure of merit (ZT) of 0.17 at 600 °C.
dc.identifier.citationMaterials Science in Semiconductor Processing, 215, 2026
dc.identifier.doi10.1016/j.mssp.2026.111024
dc.identifier.issn13698001
dc.identifier.other2-s2.0-105045576856
dc.identifier.urihttps://dspace.kmitl.ac.th/handle/123456789/18335
dc.sourceMaterials Science in Semiconductor Processing
dc.subjectCa3Co4O9
dc.subjectCombustion
dc.subjectOxide thermoelectric materials
dc.subjectSeebeck coefficient
dc.subjectThemoelectricity
dc.titleEnhanced densification and thermoelectric properties of Ca3Co4O9 ceramics fabricated by solid-state combustion and hot-pressing
dc.typeArticle

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