Site disorder exists in some practical semiconductors and can significantly impact their intrinsic properties both beneficially and detrimentally.However,the uncertain local order and structure pose a challenge for ex...Site disorder exists in some practical semiconductors and can significantly impact their intrinsic properties both beneficially and detrimentally.However,the uncertain local order and structure pose a challenge for experimental and theoretical research.Especially,it hinders the investigation of the effects of the diverse local atomic environments resulting from the site disorder.We employ the special quasi-random structure method to perform first-principles research on connection between local site disorder and electronic/optical properties,using cationdisordered AgBiS_(2)(rock salt phase)as an example.We predict that cation-disordered AgBiS_(2)has a bandgap ranging from 0.6 to 0.8 eV without spin-orbit coupling and that spin-orbit coupling reduces this by approximately 0.3 eV.We observe the effects of local structural features in the disordered lattice,such as the one-dimensional chain-like aggregation of cations that results in formation of doping energy bands near the band edges,formation and broadening of band-tail states,and the disturbance in the local electrostatic potential,which significantly reduces the bandgap and stability.The influence of these ordered features on the optical properties is confined to alterations in the bandgap and does not markedly affect the joint density of states or optical absorption.Our study provides a research roadmap for exploring the electronic structure of site-disordered semiconductor materials,suggests that the ordered chain-like aggregation of cations is an effective way to regulate the bandgap of AgBiS_(2),and provides insight into how variations in local order associated with processing can affect properties.展开更多
We report electronic and magnetic properties of full Heusler Pd_(2)TiIn based on first principles calculations.This compound has been variously characterized as magnetic or non-magnetic.We use first principles calcula...We report electronic and magnetic properties of full Heusler Pd_(2)TiIn based on first principles calculations.This compound has been variously characterized as magnetic or non-magnetic.We use first principles calculations with accurate methods to reexamine this issue.We find that ideal ordered Heusler Pd_(2)TiIn remains non-magnetic,in accord with prior work.However,we do find that it is possible to explain the magnetism seen in experiments through disorder and in particular we find that site disorder can lead to moment formation in this compound.In addition,we find an alternative low energy cubic crystal structure,which will be of interest to explore experimentally.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.62125402,22090044,and 12350410372)the National Key Research and Development Program of China(Grant No.2022YFA1402501)Graduate Innovation Fund of Jilin University(Grant No.2022118)。
文摘Site disorder exists in some practical semiconductors and can significantly impact their intrinsic properties both beneficially and detrimentally.However,the uncertain local order and structure pose a challenge for experimental and theoretical research.Especially,it hinders the investigation of the effects of the diverse local atomic environments resulting from the site disorder.We employ the special quasi-random structure method to perform first-principles research on connection between local site disorder and electronic/optical properties,using cationdisordered AgBiS_(2)(rock salt phase)as an example.We predict that cation-disordered AgBiS_(2)has a bandgap ranging from 0.6 to 0.8 eV without spin-orbit coupling and that spin-orbit coupling reduces this by approximately 0.3 eV.We observe the effects of local structural features in the disordered lattice,such as the one-dimensional chain-like aggregation of cations that results in formation of doping energy bands near the band edges,formation and broadening of band-tail states,and the disturbance in the local electrostatic potential,which significantly reduces the bandgap and stability.The influence of these ordered features on the optical properties is confined to alterations in the bandgap and does not markedly affect the joint density of states or optical absorption.Our study provides a research roadmap for exploring the electronic structure of site-disordered semiconductor materials,suggests that the ordered chain-like aggregation of cations is an effective way to regulate the bandgap of AgBiS_(2),and provides insight into how variations in local order associated with processing can affect properties.
基金Supported by the National Natural Science Foundation of China(Grant Nos.51861145315,51672171,12074241and 51911530124)the Department of Energy,Basic Energy Sciences(Award DE-SC0019114)for work at the University of Missouri+3 种基金the Shanghai Municipal Science and Technology Commission Program(Grant No.19010500500)the China Scholarship Council(CSC)the Independent Research Project of State Key Laboratory of Advanced Special Steel and Shanghai Key Laboratory of Advanced Ferrometallurgy at Shanghai Universitythe State Key Laboratory of Solidification Processing in NWPU(Grant No.SKLSP201703)。
文摘We report electronic and magnetic properties of full Heusler Pd_(2)TiIn based on first principles calculations.This compound has been variously characterized as magnetic or non-magnetic.We use first principles calculations with accurate methods to reexamine this issue.We find that ideal ordered Heusler Pd_(2)TiIn remains non-magnetic,in accord with prior work.However,we do find that it is possible to explain the magnetism seen in experiments through disorder and in particular we find that site disorder can lead to moment formation in this compound.In addition,we find an alternative low energy cubic crystal structure,which will be of interest to explore experimentally.
