Layered structure of alumina/graphene-augmented-inorganic-nanofibers with directional electrical conductivity

Ali Saffar Shamshirgar, Rocio Estefania Rojas Hernandez, Girish C. Tewari, Roman Ivanov, Valdek Mikli, Maarit Karppinen, Irina Hussainova

Research output: Contribution to journalArticleScientificpeer-review

5 Citations (Scopus)

Abstract

Implementation of layered structures with strong nanoscale optimized interfaces, enables engineering of materials with functional properties. In this work, anisotropic functional multi-layered structures are produced by integration of a thin hybrid inter-layer of graphene-augmented-nanofibers/alumina into α-alumina through an ex-situ strategy of precipitating the tailored hybrid from a solution. Spark plasma sintering was used to consolidate the layered structures at 1150 and 1450 °C under 75 and 50 MPa pressure. Raman spectroscopy suggests presence of C–H bonds and sp3 hybridization for the samples sintered at 1150 °C, while graphene structure is purified at the sintering temperature of 1450 °C. The multilayer structures demonstrate a high in-plane electrical conductivity which can be modulated, ranging from 300 to 1800 S m−1 as a function of the interlayer thickness and the carbon content. A p-type conduction at room temperature and n-type down to 4 K in graphene-augmented nano-fillers was observed in Hall measurement. However, the multilayered systems display a p-type conduction in the entire temperature range. Hardness was preserved despite the high concentration of the graphene-augmented nano-fillers in the hybrid interlayer leaving a highest value of ∼22 GPa. The results have the potential to fuel the development of functional electronic enclosures with additional functionalities such as electromagnetic interference shielding.
Original languageEnglish
Pages (from-to)634-645
Number of pages12
JournalCarbon
Volume167
DOIs
Publication statusPublished - 15 Oct 2020
MoE publication typeA1 Journal article-refereed

Keywords

  • Hierarchical structures
  • Hybrid materials
  • Ceramics
  • Graphene
  • Anisotrophy

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