摘要
非晶态物质的本质及形成过程是凝聚态物理领域最困难也是最有趣的问题之一.非晶形成过程在原子结构上不会衍生出人们在传统晶体结构里所熟悉的长程有序性,因此对于此类在自然界中广泛存在的物质形态,至今还没有有效的实验表征手段和理论研究方法.非晶态物质的原子结构及其构效关系的研究是凝聚态物理和材料科学等众多研究领域所关注的热点问题之一.随着对非晶态物质物性研究的深入,人们逐渐意识到非晶态物质中原子中程序对系统性质的重要影响,建立以中程序为基础的结构-动力学关系对于理解玻璃及玻璃转变的本质起着重要的作用.本文简要综述了基于图论提出的原子局域连接度这一新的结构序参量在液体和玻璃的结构及构效关系研究中的应用.新的结构序参量从过去侧重于关注局域原子团簇的种类和分布,转移到更加关注某一类具有特殊对称性的原子的空间连接情况,即更多地尝试从原子中程序的角度来建立非晶态物质中的构效关系.新的研究结果表明,局域连接度可与非晶态物质中原子的短时或长时动力学行为、输运方式、以及振动模态等一系列物理性质建立联系.
For a long time,it has been well recognized that there exists a deep link between the fast vibrational excitations and the slow diffusive dynamics in glass-forming systems.However,it remains as an open question whether and how the short-time scale dynamics associated with vibrational intrabasin excitations is related to the long-time dynamics associated with diffusive interbasin hoppings.In this paper we briefly review the research progress that addresses this challenge.By identifying a structural order parameter—local connectivity of a particle which is defined as the number of nearest neighbors having the same local spatial symmetry,it is found that the local connectivity can tune and modulate both the short-time vibrational dynamics and the longtime relaxation dynamics of the studied particles in a model of metallic supercooled liquid.Furthermore,it reveals that the local connectivity leads the long-time decay of the correlation functions to change from stretched exponentials to compressed ones,indicating a dynamic crossover from diffusive to hyperdiffusive motions.This is the first time to report that in supercooled liquids the particles with particular spatial symmetry can present a faster-than-exponential relaxation that has so far only been reported in out-ofequilibrium materials.The recent results suggest a structural bridge to link the fast vibrational dynamics to the slow structural relaxation in glass-forming systems and extends the compressed exponential relaxation phenomenon from earlier reported out-of-equilibrium materials to the metastable supercooled liquids.
作者
武振伟
汪卫华
Wu Zhen-Wei;Wang Wei-Hua(School of Systems Science,Beijing Normal University,Beijing 100875,China;Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2020年第6期1-16,共16页
Acta Physica Sinica
基金
国家自然科学基金(批准号:11804027)
中央高校基本科研业务费(批准号:2018NTST24)资助的课题~~
关键词
非晶合金
过冷液体
局域连接度
弛豫动力学
amorphous alloys
supercooled liquids
local connectivity
relaxation dynamics
作者简介
通信作者:武振伟,北京大学力学与工程科学系理学博士,北京大学物理学院量子材料科学中心博雅博士后,现就职于北京师范大学系统科学学院.曾获博士研究生国家奖学金和北京大学优秀博士学位论文奖等奖励.长期从事非晶态物理领域的研究工作,以计算机模拟结合统计力学、图论等研究方法,探索过冷液体和玻璃态物质等典型无序系统的结构与结构动力学关系.代表性工作为具有拓扑属性的原子结构描述参量的提出及其构效关系研究.E-mail:zwwu@bnu.edu.cn;汪卫华,中国科学院院士,博士生导师,主要从事新型大块非晶及其他亚稳材料的制备、结构、物性研究,研制出多种厘米级的大块非晶合金等亚稳材料,并系统研究了其微结构及物理性能,建立了一系列有自己特色的制备和研究亚稳材料的方法;近年来,致力于非晶合金材料的高通量设计、制备及表征工作,在国际著名期刊Science,Nature,Nature Materials,Physical Review Letters,Advanced Materials,Physical Review B,Applied Physical Letters等上发表科研论文500余篇,在Adv.Mater.,Prog.Mater.Sci.,Mater.Sci.Eng.R,Acta Mater.等上发表邀请综述性文章6篇,SCI引用超过两万次.