Physical property characterization of bulk MgB2 superconductor
| Autor: | H. Kishan, V.P.S. Awana, Arpita Vajpaye, G.L. Bhalla, A. M. Awasthi, Monika Mudgel, V. Ganesan |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
Superconductivity
Materials science Strongly Correlated Electrons (cond-mat.str-el) Condensed matter physics Condensed Matter - Superconductivity FOS: Physical sciences Condensed Matter Physics Magnetic susceptibility Electronic Optical and Magnetic Materials Superconductivity (cond-mat.supr-con) Condensed Matter - Strongly Correlated Electrons Magnetization symbols.namesake Thermal conductivity Electrical resistivity and conductivity Seebeck coefficient symbols Grain boundary Debye model |
| Zdroj: | The European Physical Journal B. 62:281-294 |
| ISSN: | 1434-6036 1434-6028 |
| DOI: | 10.1140/epjb/e2008-00174-1 |
| Popis: | We report synthesis, structure/micro-structure, resistivity under magnetic field [R(T)H], Raman spectra, thermoelectric power S(T), thermal conductivity K(T), and magnetization of ambient pressure argon annealed polycrystalline bulk samples of MgB2, processed under identical conditions. The compound crystallizes in hexagonal structure with space group P6/mmm. Transmission electron microscopy (TEM) reveals electron micrographs showing various types of defect features along with the presence of 3-4nm thick amorphous layers forming the grain boundaries of otherwise crystalline MgB2. Raman spectra of the compound at room temperature exhibited characteristic phonon peak at 600 cm-1. Superconductivity is observed at 37.2K by magnetic susceptibility C(T), resistivity R(T), thermoelectric power S(T), and thermal conductivity K(T) measurements. The power law fitting of R(T) give rise to Debye temperature at 1400K which is found consistent with the theoretical fitting of S(T), exhibiting ThetaD of 1410K and carrier density of 3.81x 1028/m3. Thermal conductivity K(T) shows a jump at 38K, i.e., at Tc, which was missing in some earlier reports. Critical current density (Jc) of up to 105 A/cm2 in 1-2T (Tesla) fields at temperatures (T) of up to 10K is seen from magnetization measurements. The irreversibility field, defined as the field related to merging of M(H) loops is found to be 78, 68 and 42 kOe at 4, 10 and 20K respectively. The superconducting performance parameters viz. irreversibility field (Hirr) and critical current density Jc(H) of the studied MgB2 are improved profoundly with addition of nano-SiC and nano-Diamond. The physical property parameters measured for polycrystalline MgB2 are compared with earlier reports and a consolidated insight of various physical properties is presented. 41 pages TEXT+Figs |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|