Polycrystalline bulk body and method for producing same
AssigneesNational Institute of Advanced Industrial Science and Technology, Aisin Corporation
InventorsHiraku Ogino, Shigeyuki Ishida, PavanKumarNaik Sugali, Hiroshi Eisaki, Akira Iyo, Kenji Kawashima, Yoshihisa Kamiya
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Abstract
A polycrystalline bulk body of this invention has uniformity in superconducting properties, in comparison to a polycrystalline bulk body including crystal grains each constituted by (Ba1-xKx)Fe2As2. A polycrystalline bulk body (1) of this invention includes crystal grains each constituted by an iron-based compound (10) expressed by chemical formula AA′Fe4As4, where A is Ca and A′ is K, the iron-based compound (10) having a crystal structure in which AFe2As2 layers (16) and A′Fe2As2 layers (17) are alternately stacked.
Claims7
A polycrystalline bulk body comprising:
- crystal grains each of which is an iron-based compound expressed by chemical formula AKFe4As4, where A is Ca, part of A is optionally substituted by at least one of Sr and Eu,
- the iron-based compound having a crystal structure in which AFe2As2 layers and KFe2As2 layers are alternately stacked,
- the crystal structure having a space group of a simple tetragonal crystal P4/mmm,
- the iron-based compound exhibiting superconductivity in a temperature range below a critical temperature,
- the crystal structure having a lattice constant, in a c-axis direction, of not less than 12.85 Å.
A method for producing a polycrystalline bulk body of an iron-based compound expressed by chemical formula AKFe4As4, where A is Ca, part of A is optionally substituted by at least one of Sr and Eu,
- said method comprising:
- a mixing step of mixing elements A, A′, Fe, and As or compounds containing A, A′, Fe, and As, each of which is a starting material;
- a pressurizing step of pressurizing a mixture resulting from the mixing in the mixing step;
- and
- a heating step of heating the mixture at a temperature of not less than 750° C. and not more than 1000° C. in a state where the mixture is sealed in a container, the heating step being carried out after or in parallel with the pressurizing step,
- the iron-based compound having a crystal structure, and the crystal structure having a lattice constant, in a c-axis direction, of not less than 12.85 Å.
Dependencies are inferred from the claim text.