Synthesis and Properties of New Layr Structured Superconductors

在之前的研究中，我们通过锂嵌入氮化层的电子掺杂，从层结构的β - zrnc1中获得了一种新型超导体。这一发现表明，氮化物层可以像氧化铜超导体的CuO_2层一样成为良好的超导基质。在本研究中，制备了一系列β - zrncl型层状氮化物，并对电子掺杂后超导的可能性进行了研究。研究了新型层状结构氮化物超导体的发展。本研究的一些重要结果如下：1。通过在β - hfncl中嵌入锂，获得了Tc高达25.5 K的新型高Tc超导体。注意，Tc （25.5 K）远高于具有岩盐结构的HfN的Tc。在高压和高温条件下制备了MNX （M = Zr, Hf; X = C1, Br， I）晶体的所有组合。通过电子掺杂，所有晶体均表现出超导性。Tcs主要由金属氮化层的种类决定。通过与吡啶的反应制备了与ZrNCl结构具有不同类型氮层的α - tinci插层化合物。插层化合物在6 K时表现出与Tc的超导性。这是第一个通过嵌入有机碱作为电子供体而从层状半导体中获得的超导体。采用激光研磨技术在Si（111）衬底上制备了ZrN/Si_3N_4人工超晶格薄膜。电子掺杂到薄膜中的问题目前正在调查中。

In a previous study, we derived a new type of superconductor from the layer structured beta-ZrNC1 by electron doping of the nitride layers through lithium intercalation. This finding suggests that the nitride layers may become good matrices of superconductivity like CuO_2 layers of copper oxide superconductors. In this study, a series of beta-ZrNCl type layered nitrides have been prepared and the possibility of superconductivity has been examined after electron doping. Developments of new layer structured nitride superconductors have also been studied. Some important results of this study are the following :1. A new high Tc superconductor with Tc as high as 25.5 K was obtained by intercalation of lithium in beta-HfNCl. Note that the Tc (25.5 K) is much higher than the Tc of HfN with the rock-salt structure.2. All combinations of MNX ( M = Zr, Hf ; X = C1, Br, I) crystals were prepared by using high pressure and high temperature conditions. All of the crystals showed superconductivity by electron doping. The Tcs were mainly determined by the kinds of metal nitride layers concerned.3. Intercalation compounds of alpha-TiNCI having a different type of nitride layers from that of beta ZrNCl structure were prepared by the reaction with pyridine. The intercalation compounds showed superconductivity with Tc at 6 K.This is the first superconductor derived from a layered semiconductor by intercalation of an organic base as electron donor.4. Artificial superlattice films of ZrN/Si_3N_4 were prepared on Si(111) substrate by a laser abration technique. The electron doping into the films is now under investigation.