Comparative study of hot and cold press and their effect on superconducting properties of coronene added bulk MgB2
Küçük Resim Yok
Tarih
2019
Yazarlar
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Elsevier
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
In this study, the superconducting properties of 4 wt% coronene (C24H12) added polycrystalline bulk MgB2 samples prepared by hot pressing and cold pressing, were reported in detail. The results were compared to determine one of which pressing methods is more useful to substitute of carbon released from C24H12 into MgB2 structure and to increase the superconducting properties of MgB2. The lattice strain, crystallite size, residual resistivity, superconducting transition temperature (T-c), critical current density (J(c)), flux pinning force density (F-p) and vertical/lateral levitation force (F-z,F-x) were analysed for the hot and cold pressed samples. The a-lattice parameter and T-c value reduced sharply for 4 wt% C(24)H(12)added cold pressed sample, resulting in a notable decrease of increment ratio of J(c) and F-p values, while the depressing of T-c is lower for 4 wt% C24H12 added hot pressed sample. The cold pressing strongly increased the lattice strain, confirming more C substitution, while the hot pressing ensured smaller crystallite size. The J(c) and F-p values were respectively found as 4.6 x 10(3) A/cm(2), 1.3 x 10(4) A/cm(2), 5.8 x 10(3) A/cm(2) and 1.8 x 10(8) N/m(3), 5.1 x 10(8) N/m(3), 2.3 x 10(8) N/m(3) for the pure sample and, 4 wt% C24H12 added hot and cold pressed samples at 20 K, 4 T. The maximum repulsive and attractive levitation force values at 20 K in ZFC and FC regimes were obtained for the 4 wt% C24H12 added hot pressed sample. Finally, the hot pressing provides an effective way to substitute C into MgB2 lattice without a remarkable decrease of T-c value, ensuring more homogenous and compacted structure, more electron-phonon interaction and strong flux pinning force.
Açıklama
Anahtar Kelimeler
Superconductivity, MgB2, Coronene adding, Hot press, Cold press
Kaynak
Physica C-Superconductivity and Its Applications
WoS Q Değeri
Q4
Scopus Q Değeri
Q2
Cilt
565
