Physical Origin of Color Changes in Lutetium Hydride under Pressure  

作　　者：吕润 涂文倩 邵定夫 孙玉平 鲁文建 Run Lv;Wenqian Tu;Dingfu Shao;Yuping Sun;Wenjian Lu(Key Laboratory of Materials Physics,Institute of Solid State Physics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,China;Science Island Branch of Graduate School,University of Science and Technology of China,Hefei 230026,China;High Magnetic Field Laboratory,Institute of Solid State Physics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,China;Collaborative Innovation Center of Microstructures,Nanjing University,Nanjing 210093,China)

机构地区：[1]Key Laboratory of Materials Physics,Institute of Solid State Physics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,China [2]Science Island Branch of Graduate School,University of Science and Technology of China,Hefei 230026,China [3]High Magnetic Field Laboratory,Institute of Solid State Physics,Hefei Institutes of Physical Science,Chinese Academy of Sciences,Hefei 230031,China [4]Collaborative Innovation Center of Microstructures,Nanjing University,Nanjing 210093,China

出　　处：《Chinese Physics Letters》2023年第11期120-125,共6页中国物理快报（英文版）

基　　金：supported by the National Key Research and Development Program of China(Grant Nos.2022YFA1403203 and 2021YFA1600200);the National Natural Science Foundation of China(Grant Nos.U2032215 and 12241405)。

摘　　要：Recently,near-ambient superconductivity was claimed in nitrogen-doped lutetium hydride(LuH_(3-δ)N_(ε)).Unfortunately,all follow-up research still cannot find superconductivity signs in successfully synthesized lutetium dihydride(LuH_(2)) and N-doped LuH_(2±x)N_(y).However,a similar intriguing observation was the pressure-induced color changes(from blue to pink and subsequent red).The physical understanding of its origin and the correlation between the color,crystal structure,and chemical composition of Lu–H–N is still lacking.In this work,we systematically investigated the optical properties of LuH_(2) and LuH_(3),and the effects of hydrogen vacancies and nitrogen doping using the first-principles calculations by considering both interband and intraband contributions.Our results demonstrate that the evolution of reflectivity peaks near blue and red light,which is driven by changes in the band gap and Fermi velocity of free electrons,resulting in the blue-to-red color change under pressure.In contrast,LuH_(3) exhibits gray and no color change up to 50 GPa.Furthermore,we investigated the effects of hydrogen vacancies and nitrogen doping on its optical properties.Hydrogen vacancies can significantly decrease the pressure of blue-to-red color change in LuH_(2) but do not have a noticeable effect on the color of LuH_(3).The N-doped LuH_(2) with the substitution of a hydrogen atom at the tetrahedral position maintains the color change when the N-doping concentration is low.As the doping level increases,this trend becomes less obvious,while other N-doped structures do not show a blue-to-red color change.Our results can clarify the origin of the experimental observed blue-to-red color change in lutetium hydride and also provide a further understanding of the potential N-doped lutetium dihydride.

关 键 词：HYDRIDE DOPING ORIGIN 

分 类 号：O469[理学—凝聚态物理]