Issue |
EPL
Volume 86, Number 3, May 2009
|
|
---|---|---|
Article Number | 37008 | |
Number of page(s) | 4 | |
Section | Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties | |
DOI | https://doi.org/10.1209/0295-5075/86/37008 | |
Published online | 22 May 2009 |
Preparation and superconductivity of stoichiometric β-FeSe
1
State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences - Shanghai 200050, PRC
2
Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences Shanghai 200050, PRC
Corresponding author: huangfq@mail.sic.ac.cn
Received:
20
January
2009
Accepted:
6
April
2009
The stoichiometric -FeSe superconductor was prepared for the first time by mechanical alloying (MA) from elemental powders of iron and selenium (1 : 1) and subsequent annealing process. The formation of the stoichiometric
-FeSe is attributed to the MA resulting nanometric precursor containing high reaction activity for the following annealing process, and the MA mechanism here is a mechanic collision reaction (MCR). The crystalline phases in the MA precursor are tightly related to the milling time (t). Hexagonal γ-Fe7Se8, tetragonal
-FeSe, and residual Fe coexist when t
5 h. A single
-FeSe phase is observed when t = 10 h, and the crystalline size further decreases to ~ 10 nm. In the nanocrystalline state, hexagonal
-FeSe is the stable and preferred phase. With the increase of the annealing temperature,
-FeSe rapidly transforms to the well-crystallized
-FeSe. At 400 °C, the pure stoichiometric
-FeSe phase is successfully obtained with size of ~ 60 nm and the highest superconductor transition temperature
of about 8.9 K in the
-FeSe
series.
PACS: 74.70.-b – Superconducting materials / 74.70.Ad – Metals; alloys and binary compounds (including A15, MgB2, etc.)
© EPLA, 2009
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