Thermopower and hall effect in silicon nitride composites containing thermally reduced graphene and pure graphene nanosheets

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• 作者：C. Ramirez^a ; ¹ ; V. Leborá ; n^b ; F. Rivadulla^b ; P. Miranzo^a ; M.I. Osendi^a ; ^{miosendi@icv.csic.es" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Graphene ; Graphene oxide ; Ceramics ; Si3N4 ; Thermopower ; Hall effect ; STEM ; N-doping ; nanoclusters
• 刊名：Ceramics International
• 出版年：2016
• 出版时间：July 2016
• 年：2016
• 卷：42
• 期：9
• 页码：11341-11347
• 全文大小：2240 K

文摘

Composites consisting of dielectric silicon nitride (Si₃N₄) with diverse percentages of different graphene nanoreinforcements, such as graphene nanoplatelets (GNP) – 17 and 21 vol% – and reduced graphene oxide (rGO) sheets − 4 and 7 vol% – displayed thermopower effect. Maximum thermopower was observed for the rGO containing composites, which reached a peak Seebeck coefficient (S) of −26 μV K⁻¹ at 300 K, whereas GNP composites showed top S of +5 μV K⁻¹ at the same temperature. Hall effect measurements indicated that current carriers were different in both composites, electrons for the rGO/Si₃N₄ (n-type conductor) and holes for the GNP/Si₃N₄ materials (p-type conductor) and also having ∼1.4 times higher carrier concentration the first composites. The enhanced thermopower of the rGO/Si₃N₄ composites is attributed to the particular defective nature of rGO sheets, which presented edge defects and nanometer scale defect clusters as shown by the high resolution transmission electron microscope images – probably associated to both oxygen atoms remaining after GO reduction during spark plasma sintering and N doping from the Si₃N₄ matrix.