Containerless Processing of Metastable Multiferroic Composite in R-Fe-O System (R: Rare-earth element)

DOI:10.15011/jasma.33.330215
Int. J. Microgravity Sci. Appl. 2016p330215
Author
Kazuhiko KURIBAYASHI, Ryota TAKAHASHI, Yuko INATOMI, Shumpei OZAWA and M. S. VIJAYA KUMAR
Organization
Department of Advanced Materials Science and Engineering, Chiba Institute of Technology, Institute of Space and Astronautical Science, JAXA, Department of Mechanical Engineering, Tufts University
Abstract
The hexagonal structure with a space group of P63cm has been known to be stable in the RMnO3 system (R: rare earth element) of the rare earth elements having smaller ionic radius. The hexagonal RMnO3 (h-RMnO3) has attracted great interest towards their wide applications in the field of electronic industry, because h-RMnO3 shows multiferroic properties such as ferroelectricity, ferromagnetism and ferroelasticity in the same phase. Nevertheless, the materials for practical applications remain undeveloped, because h-RMnO3 shows anti-ferromagnetism as well as low magnetic transformation temperature below 100 K. To solve this problem, we considered that a composite of a ferromagnetic phase and a ferroelectric phase is more realistic than a single-phase material. On the basis of this idea, we attempted to synthesize the multiferroic composite consisting of ferroelectric h-RFeO3 and ferromagnetic Fe3O4 by utilizing the containerless technique. The experimental result showed that it is possible to exhibit a fine composite structure when h-LuFeO3 and Fe3O4 are equimolar amounts. However, the orthorhombic phase (o-RFeO3) as well as h-RFeO3 was observed in the samples in which the mole-fraction of Fe3O4 was increased. The reason for forming the o-RFeO3 phase is attributed to the decrease of the driving force for forming a metastable phase due to the fact that the solute atom or molecule is redistributed at the solid-liquid interface of the growing crystal.
Keyword(s)
Containerless processing, Undercooling, Rapid solidification, Multiferroic materials
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Received 20 September 2015, Accepted 30 December 2015, Published 30 April 2016

© The Japan Society of Microgravity Applicaiton

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