Structural phase evolution and superconductivity in the non-stoichiometric intermetallic compound niobium diboride

IF 1 3区物理与天体物理 Q4 PHYSICS, APPLIED Physica C-superconductivity and Its Applications Pub Date : 2008-03-01 Epub Date: 2008-01-11 DOI:10.1016/j.physc.2008.01.001

Zhi-An Ren, Sogo Kuroiwa, Yoko Tomita, Jun Akimitsu

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引用次数: 21

Abstract

The structural changes and superconductivity in the layered non-stoichiometric niobium diboride compound were systematically studied for both of niobium-deficient and boron-deficient phases by X-ray diffraction analysis and magnetic susceptibility measurements. The niobium and boron vacancies were found to have different effects on the crystal lattice parameters and superconducting properties; superconductivity only exists in niobium-deficient phases with a clear enhancement of inner-plane B–B bonding and the increase of inter-plane distance, while boron vacancies have the opposite effect of enhancing the Nb–B bonding and breaking the superconductivity. A main superconducting phase with Nb_0.83B₂ composition was obtained with T_c ∼ 9.3–9.9 K, and a = 3.102(1) Å and c = 3.322(2) Å under the optimum sintering conditions. The low temperature specific heat was measured for three high-pressure synthesized superconducting samples to reveal the origin the increase of T_c with the niobium deficiencies.

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非化学计量金属间化合物二硼化铌的结构、相演化和超导性

通过x射线衍射分析和磁化率测量，系统地研究了层状非化学计量二硼化铌化合物中缺铌和缺硼相的结构变化和超导性。铌和硼空位对晶体晶格参数和超导性能有不同的影响;超导电性只存在于缺铌相中，并明显增强了内面B-B键，增加了面间距离，而缺硼空位则增强了内面B-B键，破坏了超导电性。在最佳烧结条件下，在Tc ~ 9.3 ~ 9.9 K条件下，A = 3.102(1) Å， c = 3.322(2) Å，得到了以Nb0.83B2为主的超导相。对三种高压合成超导样品进行了低温比热测量，揭示了Tc随铌缺乏而升高的原因。

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来源期刊

Physica C-superconductivity and Its Applications 物理-物理：应用

CiteScore

2.70

自引率

11.80%

发文量

102

审稿时长

66 days

期刊介绍： Physica C (Superconductivity and its Applications) publishes peer-reviewed papers on novel developments in the field of superconductivity. Topics include discovery of new superconducting materials and elucidation of their mechanisms, physics of vortex matter, enhancement of critical properties of superconductors, identification of novel properties and processing methods that improve their performance and promote new routes to applications of superconductivity. The main goal of the journal is to publish: 1. Papers that substantially increase the understanding of the fundamental aspects and mechanisms of superconductivity and vortex matter through theoretical and experimental methods. 2. Papers that report on novel physical properties and processing of materials that substantially enhance their critical performance. 3. Papers that promote new or improved routes to applications of superconductivity and/or superconducting materials, and proof-of-concept novel proto-type superconducting devices. The editors of the journal will select papers that are well written and based on thorough research that provide truly novel insights.