Characterization of FeSe single crystals

Hiroyuki Takeya, Shigeru Kasahara, Kazuto Hirata, Takashi Mochiku, Akira Sato, Yoshihiko Takano

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


Superconductivity at 8 K was reported in β-FeSe with a tetragonal PbO structure but not in δ-FeSe with a hexagonal NiAs structure. The superconducting transition temperature was then increased up to 37 K (on-set) by high pressure on polycrystalline samples. We report a study of the characterization on single crystals of FeSe superconductors. FeSe single crystals were grown using two methods, simple cooling from stoichiometric melt and flux using NaCl/KCl. While a ball-shaped aggregation composed of thick FeSe crystals was grown from the stoichiometric melt, thin hexagonal-shaped crystals with a size up to 1 mm were grown using the NaCl/KCl flux. The two different crystals indicated superconductivity around at 8 K in spite of their hexagonal shape, suggesting a non-superconducting compound with the NiAs-type hexagonal structure. According to the analyses using an X-ray diffractometer and a scanning electron microscope, the crystals contain microcracks that could be caused by stress. We assume that the hexagonal-shaped crystals grown at high temperature may turn partly to tetragonal β-FeSe at the β-δ structure transition temperature.

Original languageEnglish
Pages (from-to)S497-S498
JournalPhysica C: Superconductivity and its applications
Issue numberSUPPL.1
Publication statusPublished - Dec 2010
Externally publishedYes


  • FeSe
  • Single crystal
  • Superconductor
  • X-ray diffraction

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering


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