Preparation and Properties of Layer Structured High-Tc Superconductors

层状结构高温超导体的制备及性能

• 批准号: 12450353
• 负责人: YAMANAKA Shoji
• 金额: $ 10.37万
• 依托单位: HIROSHIMA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2000
• 资助国家: 日本
• 起止时间: 2000 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12450353/
• 关键词: Superconductor; Layer structured nitrides; Single crystal growth; High pressure synthesis; Anisotropic superconductivity; Nitride thin films; 高温超伝導; インターカレーション; 電子ドープ; NMR; 単結晶

1. The layer structured nitride chlorides, β-MNCl (M = Zr, Hf) can be electron-doped by the intercalation of lithium, and are changed into superconductors with the superconducting transition temperatures (Tc's) of 14 and 25.5 K for M = Zr and Hf, respectively. The interlayer spacing can be controlled by the co-intercalation of polar solvent molecules with lithium ions, and the anisotropy of the superconductivity is greatly enhanced. The NMR and muon spin relation measurements revealed that the electron-doped layer structured nitride superconductors have the following characteristics ; (i) highly anisotropic exotic superconductors, (ii) low carrier density near Fermi level, 〜10^<21>/cm^3, (iii) very small isotope effect on the replacement with ^<15>N, and (iv) low phonon excitation. The superconductivity is very unconventional.2. The layer structured nitride chlorides, β-MNCl (M = Zr, Hf) were so thin and so soft crystals that it was very difficult to use for X-ray structural analysis a … More nd physical property measurements. We have succeeded to develop a new high pressure synthesis method to obtain thick single crystals using ammonium chloride as flux. All kinds of β-MNX (M = Zr, Hf ; X = Cl, Br, I) were also obtained as single crystals, and the crystal structures were determined by X-ray single crystal analyses. It was found that the compounds were crystallized into the two different polytypes, the SmSI and the YOF structures.3. In an attempt to tailor new layer structured nitride compounds, thin artificial nitride films were prepared using electron-beam evaporation and lazer ablation methods with a nitrogen radical source under ultrahigh vacuum conditions. Titanium nitride, TiN, films were epitaxially grown on MgO (100) substrates, and the layer-by-layer growth was successfully monitored by RHEED. CrN could be epitaxially deposited on Si(100), and an expitaxial NbN film was subsequently grown on the CrN film. This finding suggests the possibility of the synthesis of artificial CrN-NbN films with superstructures. Less

1。层结构化氮化物β-MNCL（M = ZR，HF）可以通过锂的插入来电子掺杂，并将超导过渡温度（TC）（TC）转换为超导型超导体，分别为14和25.5 k，分别为M = ZR和HF。层间间距可以通过极性溶剂分子与锂离子的共同点进行控制，并且超导性的各向异性大大增强。 NMR和MUON自旋关系测量结果表明，电子掺杂的氮化氮化物超导体具有以下特征。 （i）高度各向异性外来的超导体，（ii）菲尔米水平接近的低载体密度，〜10^<21>/cm^3，（iii）对用^<15> n和（iv）低音子令人兴奋的替换对替换的非常小的同位素效应。超导性非常规。2。层结构化的氮化物氯化物β-MNCL（M = ZR，HF）是如此薄且柔软的晶体，以至于很难用于X射线结构分析A…更多ND物理性能测量。我们已经成功开发了一种新的高压合成方法，以使用氯化铵作为通量获得厚的单晶。还以单晶体的形式获得了各种β-MNX（M = ZR，HF； X = Cl，Br，I），并通过X射线单晶体分析确定晶体结构。发现这些化合物结晶成两个不同的多型SMSI和YOF结构3。为了量身定制新层结构化的氮化物化合物，使用电子束蒸发和在超高真空条件下具有氮自由基源的电子束蒸发方法制备了薄薄的人造氮化物膜。氮化钛，锡，膜是在MGO（100）底物上的外延生长的，Rheed成功地监测了逐层生长。 CRN可以在SI（100）上外延沉积，随后在CRN膜上生长了裸露的NBN薄膜。这一发现表明，与上层建筑合成人造CRN-NBN膜的可能性。较少的