新型锕填充硼碳笼型化合物的超导电性  

Superconductivity in Novel Actinide Filled Boron Carbon Clathrates

作　　者：张王颖 刘朝厅 陈蕊[1] 蒋成澳 李培芳[2] 闫岩[1] ZHANG Wangying;LIU Chaoting;CHEN Rui;JIANG Chengao;LI Peifang;YAN Yan(College of Science,Changchun University,Changchun 130022,Jilin,China;College of Mathematics and Physics,Inner Mongolia Minzu University,Tongliao 028043,Inner Mongolia,China)

机构地区：[1]长春大学理学院,吉林长春130022 [2]内蒙古民族大学数理学院,内蒙古通辽028043

出　　处：《高压物理学报》2024年第2期78-86,共9页Chinese Journal of High Pressure Physics

基　　金：吉林省科技发展计划项目(20230101183JC,20230508145RC)。

摘　　要：Ac元素作为锕系第一号元素,AcH_(10)的超导转变温度(T_(c))达到251 K,是潜在的室温超导体。XB_(3)C_(3)(X表示不同的金属掺杂元素)是新发现的sp~3笼型化合物,同时具有强共价特性和超导特性,是潜在的高温超导材料。采用第一性原理密度泛函理论,探索以XB_(3)C_(3)、XB_(2)C_(4)和XB_(4)C_(2)笼型结构为原型、引入Ac元素掺杂的AcB_(3)C_(3)、AcB_(2)C_(4)和AcB_(4)C_(2)的晶体结构、晶格动力学、电子性质和超导特性。研究发现:AcB_(2)C_(4)在0~200 GPa区间内难以合成;常压下AcB_(3)C_(3)表现为间接带隙半导体,带隙宽度约为1.154 eV。根据力学稳定性判据可知,AcB_(3)C_(3)和AcB_(4)C_(2)是弹性稳定的具有较高硬度和刚度的脆性材料。同时,常压下AcB_(4)C_(2)表现出超导特性,超导转变温度达到1.565 K。随着压强的增加,超导转变温度呈现先降低后升高的变化趋势,其超导机制由中频声子主导转变为低频与中频声子的共同作用。研究结果可为实验合成笼型化合物超导材料提供理论指导,为探索具有高超导转变温度的超导材料提供新思路。Recently,a large number of theoretical and experimental studies have reported the emergence of a new sp^(3) clathrate XB_(3)C_(3),where X represents different metal doping elements.The potential hightemperature superconducting materials have been discovered.New-typical cage material with both strong covalent and superconducting properties has important scientific research significance.In recent years,Ac discovered as the first element of the actinide series,AcH_(10) has a superconducting transition temperature(T_(c))of 251 K,making it a potential room temperature superconductor.Therefore,in this article,first principles density functional theory is used to explore the crystal structure,lattice dynamics,electronic properties,and superconducting properties of AcB_(3)C_(3),AcB_(2)C_(4),and AcB_(4)C_(2) doped with Ac elements based on the cage structures of XB_(3)C_(3),XB_(2)C_(4),and XB_(4)C_(2).Research has found that AcB_(2)C_(4) is difficult to synthesize within the0-200 GPa range,and AcB_(3)C_(3) exhibits an indirect bandgap semiconductor with a bandgap width of approximately 1.154 eV at atmospheric pressure.Based on the mechanical stability criterion,it can be inferred that AcB_(3)C_(3) and AcB_(4)C_(2) are brittle materials with high hardness and stiffness that are elastically stable.At the same time,AcB_(4)C_(2) exhibits superconducting properties at ambient pressure,with T_(c) reaching1.565 K.It has been observed that as pressure increases,the T_(c) value exhibits a trend of initially decreasing and then increasing.The superconducting mechanism is mainly influenced by intermediate-frequencies phonons,which then shift to the combination of low-frequencies and intermediate-frequencies phonons.This study provides guidance for the experimental synthesis of cage type compound superconducting materials and provides new ideas for exploring superconducting materials with high superconducting transition temperature.

关 键 词：笼型化合物 第一性原理 超导电性 超导转变温度 

分 类 号：O521.2[理学—高压高温物理]