Effect of Synthesis Conditions on Formation, Electrical Properties, and Seebeck Coefficient of p-Type Ca₃Co₄O_9±δ Thermoelectric Ceramics

详细信息    查看全文

• 作者：T. Radhika ; N. Raghu ; N. Powrnami ; R. Jothi Ramalingam…
• 关键词：Ca3Co4O9±δ ; thermoelectric ; sintering ; particle size ; cobalt oxide
• 刊名：Journal of Electronic Materials
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：46
• 期：3
• 页码：1787-1793
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Optical and Electronic Materials; Characterization and Evaluation of Materials; Electronics and Microelectronics, Instrumentation; Solid State Physics;
• 出版者：Springer US
• ISSN：1543-186X
• 卷排序：46

文摘

Ca₃Co₄O_9±δ ceramic powders have been prepared by a solid-state method. The calcination and sintering temperatures and reaction conditions were varied to achieve highly dense materials for thermoelectric applications. The optimized calcination temperature and reaction conditions were derived. X-ray diffraction patterns showed formation of secondary phases for longer calcination duration. The density of the ceramics ranged from 3.2 g cm−3 to 3.4 g cm−3, not varying greatly with the calcination/sintering conditions. The electrical properties and Seebeck coefficient reveal that the density and nonstoichiometry greatly influenced the achievement of good thermoelectric properties. Transmission electron microscopy (TEM) images showed fine particles with nanosize, strongly bound together to form metal-rich particle aggregates. Tubular morphology below 50 nm to 100 nm scale was observed in TEM images of as-prepared solid-state Ca₃Co₄O_9±δ. As-prepared samples showed improved electrical conductivity and Seebeck coefficient, suitable for thermoelectric applications.