The superconducting-gap of MgB2 has been studied by high-resolution angle-resolved photoemission spectroscopy. The results show that superconducting gaps with values of 5.5 and 2.2 meV open on the sigma band and the pi band, respectively, but both the gaps close at the bulk transition temperature, providing a definitive experimental evidence for the two-band superconductivity with strong interb...

The influence of different boron precursor powders on the critical current density of MgB2 superconductor with added Ni-Co-B nanoparticles is investigated. Different types of boron have different morphologies, particle sizes and impurity content, all of which have a strong impact on the critical current density ( Jc). The boron samples investigated in this study include three different boron po...

صلاخلا ـ ة : ُّ دعتُ ل ثم ةيعيبطلا تاغللا ةجلاعم تاقيبطت نم ديدعلل ايساسأ انوكم ةيعوضوملا ةئزجتلا قيبطت تامولعملا عاجرتساو صوصنلا صيخلت . نم فدهلا وه ثحبلا اذ ه قت و مي ةيعوضوملا ة ئزجتلا تا يمزراوخ ة يلاعف ضوملا دودحلا ى لع فرعتلا يف ة يبرعلا صوصنلا لخاد ةيعو . م تو قايس لا اذ ه يف ة فلتخم رداصم نم ةيبرع صوصن ةسمخ لخاد اهنوظحلاي يتلا ةركفلا وأ عوضوملا تاريغت ىلع فرعتلل ةيبرعلا ةغللا ءارق نم ة...

Comparative analysis of structural and electromagnetic characteristics have been performed on nano SiCand polycarbosilane-doped MgB2 samples prepared by the dry and liquid mixing approaches. The total benefit of liquid mixing approach for fabrication of “organic” MgB2 superconductor with excellent electromagnetic performance has been demonstrated.

The past ¿fteen years have witnessed some of the more memorable discoveries in the ninety-year-old ¿eld of superconductivity, including the high-AS oxides in 1986 [1], the alkali-doped fullerenes in 1991 [2], the charge-injected fullerenes in 2000 [3], and the binary compound MgB2 in January 2001 [4]. The discovery of superconductivity at such high temperatures (40 K) in the simple rc R-metal c...

We have studied bulk MgB2 synthesized by reaction of MgH2 and B with and without SiC nanoparticles and at a range of reaction temperatures. All of the samples showed enhanced upper critical fields compared to most bulk MgB2, including the sample with 10 at. % SiC reacted at 600 °C, which showed Hc2 0 K 42 T. Extensive transmission electron microscopy TEM and STEM observations show that using Mg...

Superconductors with persistent zero-resistance currents serve as permanent magnets for high-field applications requiring a strong and stable magnetic field, such as magnetic resonance imaging (MRI). The recent global helium shortage has quickened research into high-temperature superconductors (HTSs)—materials that can be used without conventional liquid-helium cooling to 4.2 K. Herein, we demo...

We present a comparison of electron-phonon interaction in NbB2 and MgB2, calculated using full-potential, density-functional-based methods in P6/mmm crystal structure. Our results, described in terms of (i) electronic structure, (ii) phonon density of states F (ω), (iii) Eliashberg function α2F (ω), and (iv) the solutions of the isotropic Eliashberg gap equation, clearly show significant differ...

Phonon spectra have been investigated by micro-Raman scattering from 290 to 20K. New peaks at 500 and 674 cm appear below 250K in MgB2. These peaks are explained by the Fermi resonance, where Raman-active E2g intereacts with the overtone of E1u due to anhamonicity. Raman spectra of the isostructural RB2 (R=Al, Mn, Nb and Ti) have been also measured at 290K. The line width of E2g phonon of the s...

ةصلاخلا Allopeas gracilis is recorded for the first time in southern Iraq. It was collected from two localities (Abu-Al Khaseeb region and Hareer region) from Basrah city. ضرلاا عقوقلا نم ةنيع نورشعو نامث ي Allopeas gracilis مت للاخ ةرصبلا ةنيدم ،ريرح ةقطنم و بيصخلا وبا ةقطنم نم اھعمج ناسين رھش 2008 راذاو 2008 يلاوتلا ىلع . ليجستلا اذھ ربتعي دعب ةرصبلا ةنيدم نم ةيضرلاا عقاوقلا نم ثلاثلا Monacha...