abstract
Ecoceramics (environmentally conscious ceramics) are biomimetic/biomorphic ceramics, which use a naturally occurring and sustainable material as a template for their unique morphology and structure. Usually woods (or lignocellulosics) are used, due to the inherent cellular nature of their microstructures. The wood is pyrolised and the resulting carbon skeleton impregnated with a fluid, and this is then heated to combust the carbon template and convert the fluid precursor into a ceramic, while maintaining the structure of the original natural template. For the first time, ecoceramics have been made from cork, a totally sustainable wood that is harvested without harming the tree. Also for the first time, ecoceramics have been made of soft magnetic Z-type hexaferrites, in this case the room temperature multiferroic strontium Z ferrite Sr3Co2Fe24O41 (SrZ). Cork powder was pyrolised at 1000 degrees C, infiltrated with an aqueous sol-gel SrZ precursor, and then heated at 1200 degrees C/2 h to produce the ecoceramic. The cellular structure of the cork was maintained, with a small reduction in the hexagonal cell dimension to 10 mu m diameter, but the cell walls remained 1-2 mu m thick, of a similar magnitude to the hexaferrite grain size. Both magnetic and XRD data agreed that there was a small portion of the SrW phase present in these ecoceramics as well, and the magnetic loop showed a magnetically soft ecoceramic with M-s = 59.5 A m(2) kg(-1) (at 3 T), and a low H-c of 16 kA m(-1). (C) 2015 Elsevier Ltd. All rights reserved.
keywords
SILICON-CARBIDE CERAMICS; HEXAGONAL Z-FERRITE; BIOMIMETIC SYNTHESIS; TEMPERATURE; PRECURSORS; POWDER
subject category
Materials Science
authors
Pullar, RC; Marques, P; Amaral, J; Labrincha, JA
our authors
João António Labrincha Baptista
Full professor
João Cunha de Sequeira Amaral
Assistant Researcher
Pedro Lemos Marques
Research Fellowship
Rob Pullar
CollaboratorGroups
G2 - Photonic, Electronic and Magnetic Materials
G4 - Renewable Materials and Circular Economy
acknowledgements
Thanks to Amorim Cork Composites (Portugal) for supply cork powder. R.C. Pullar wishes to thank the FCT Grant SFRH/BPD/97115/2013 for supporting this work.