氮掺杂镥氢材料的成份以及压力导致的颜色变化  

Leading components and pressure-induced color changes in N-doped lutetium hydride

作　　者：陶相如 杨爱芹 杨树祥 全耘地 张朋 Xiangru Tao;Aiqin Yang;Shuxiang Yang;Yundi Quan;Peng Zhang(MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter,Shaanxi Province Key Laboratory of Advanced Functional Materials and Mesoscopic Physics,School of Physics,Xi’an Jiaotong University,Xi’an 710049,China;Zhejiang Laboratory,Hangzhou 311121,China)

机构地区：[1]MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter,Shaanxi Province Key Laboratory of Advanced Functional Materials and Mesoscopic Physics,School of Physics,Xi’an Jiaotong University,Xi’an 710049,China [2]Zhejiang Laboratory,Hangzhou 311121,China

出　　处：《Science Bulletin》2023年第13期1372-1378,M0003,共8页科学通报（英文版）

基　　金：supported by the National Natural Science Foundation of China(11604255);the Natural Science Basic Research Program of Shaanxi(2021JM-001)。

摘　　要：最近,美国罗切斯特大学的Dias实验组宣称,氮掺杂镥氢材料在1 GPa下超导转变温度可以达到294 K.此消息立刻引起了全世界的广泛关注.Dias等人的实验结果一旦被证实,就意味着人类追寻已久的常压-室温超导近在眼前.然而,后续的一系列实验均未发现氮掺杂镥氢材料在1 GPa具有超导电性.并且,Dias实验中的氮掺杂镥氢材料,其成份与结构未知.为了解决这些问题,本文通过结构搜索与第一性原理计算,发现氮掺杂镥氢材料的主成份为LuH_(2)(Fm■m),其次为LuN(Fm■m);常压下呈蓝色的LuH_(2),在压力下将逐渐变为紫色和红色;在LuH_(2)和LuN中,费米面附近主要是镥的5d电子,而氢或者氮的电子几乎缺失,使得这两种材料无法超导.本研究确认了Dias实验中氮掺杂镥氢材料的主要成份,解释了其在压力下为何会产生复杂的颜色变化,并阐明了后续实验未能发现超导电性的原因.Recent experimental study by Dasenbrock-Gammon et al.(Nature 2023;615:244)claims to have discovered room-temperature superconductivity in lutetium-nitrogen-hydrogen system at 1 GPa,which sheds light on the long-held dream of ambient superconductivity.However,all follow-up experiments found no evidence of superconductivity.The compositions and the crystal structures of the lutetium-nitrogen-hydrogen system remain unknown.By employing the density functional theory based structure prediction algorithm,we suggest that in lutetium-nitrogen-hydrogen the major component is LuH_2(Fm■m),together with minor LuN(Fm■m).The blue LuH_(2)at ambient pressure will turn into purple and red color at higher pressures,possibly accompanied by the formation of vacancies at hydrogen-sites.In LuH_(2)and LuN,the density of states at the Fermi level is dominated by the Lu-5d orbitals,while those from hydrogen and nitrogen are very small,leading to the absence of superconductivity in these two compounds.Nitrogen-doping to LuH_(2)fails to enhance the superconductivity as well.In this work,we identify the leading components in N-doped lutetium hydride,explain its intriguing color changes under pressure,and elucidate why superconductivity is absent in the follow-up experiments.

关 键 词：Ambientsuperconductivity Lutetium-nitrogen-hydrogen Leading components Colorchanges Hydrides Conventional superconductivity 

分 类 号：TB34[一般工业技术—材料科学与工程]