Science of Electron-conducting Filaments in Ion-conducting Chalcogenide Glasses

离子导电硫族化物玻璃中电子导电丝的科学

• 批准号: 1507670
• 负责人: Gang Chen
• 金额: $ 49.9万
• 依托单位: Ohio University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2021-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1507670&HistoricalAwards=false
• 关键词: Science; Electron; conducting; Filaments; Ion

NON-TECHNICAL DESCRIPTION: This proposal aims to address a fundamental question of charge and mass transport in ion-conducting glasses: how does an electric field create an electron-conducting path in metal-doped glasses (that contain S, Se or Te)? Under a strong external electric field, an electron-conducting path is created or annihilated inside the solid electrolyte depending on the direction of the electric field. The observed reversible creation/annihilation of electron-conducting paths by external fields mimics 0 and 1 states of a binary system and is the basis underlying conductive bridging random access memory (CBRAM), a novel non-volatile memory technology based upon bipolar resistive switching. The goal of this project is to understand the destruction and formation mechanism of the conductive filaments through integrated experiment/theory approaches. Success of this project provides fundamental understanding of the emerging CBRAM technology and promises transformation of electronically insulating glasses to electronically conducting glasses. The impact of this research is broadened further by engaging students typically underrepresented in science and engineering to participate in the research project. Summer internships are offered to undergraduate students through the on-campus Research Experience for Undergraduates program. Outreach to children with autism spectra disorder in Appalachian Ohio is offered through science demonstrations, workshops and summer camp activities.TECHNICAL DETAILS: Fast-ion conductors based upon solid electrolyte glasses have many advantages over their crystalline counterparts. For example, Ag doped chalcogenide glasses exhibit extremely high ionic conductivity. An interesting twist for these materials is that under a strong external electric field, an electron-conducting path is created inside the solid electrolyte. It is widely speculated that formation of metal filaments through field-driven electrochemical reactions is responsible for the enhanced electronic conductivity. However, this view leads to an erroneous prediction that superfast motion of both the metal ions and the solid electrolyte host occurs simultaneously under the external field. A hypothesis of this grant is that the electron-conducting filaments created by the external electric field are not made simply of metal, but complex semiconducting compounds that involve concentrated ions trapped by the ion-trap centers in the solid electrolytes. Prototypical metal-doped chalcogenide glasses (i.e., Ag and Cu doped Ge-Se and Sb-Te) were selected for study. Advanced experimental and theoretical techniques are applied to understand the charge and mass transport in the solid electrolytes under external fields. A novel simulation technique called experimentally constrained molecular relaxation (ECMR) is used to ensure maximal coincidence between theory and experiment. Structure, properties and dynamics of the electron-conducting filaments generated by the electric field are studied through the integrated experiment/theory approach. This project provides atomistic insight into the dynamics of filament formation and structure-property relations of the electron-conducting filaments. Undergraduate and graduate students participating in this project are trained on cutting-edge research facilities such as those in Advanced Photon Source and Center for Nanoscale Materials at Argonne National Lab and the Ohio Supercomputing Center. Outreach to children with autism spectral order is offered to enhance their interest in college education and careers in information technology.

非技术描述：该提案旨在解决离子电导玻璃中的电荷和大众传输的基本问题：电场如何在金属掺杂的玻璃杯（包含S，SE或TE）中创建电子传导路径？在强大的外部电场下，根据电场的方向形成或消灭了固体电解液内部或消灭电子导向路径。观察到的外部磁场对电子传导路径的可逆创造/an灭模仿了二元系统的0和1状态，并且是基于双极电阻开关的新型非挥发性存储器技术的基础导电桥接随机访问记忆（CBRAM）。该项目的目的是通过综合实验/理论方法来了解导电细丝的破坏和形成机制。该项目的成功提供了对新兴CBRAM技术的基本理解，并有望将电子绝缘玻璃转换为电子导电玻璃。这项研究的影响进一步扩展了科学和工程中通常不足的学生参加研究项目。通过本科生的校园研究经验，为本科生提供了暑期实习。通过科学演示，研讨会和夏令营活动提供了俄亥俄州阿巴拉契亚自闭症谱系障碍儿童的宣传。技术详细信息：基于固体电解质眼镜的快速离子导体比其结晶的镜头具有许多优势。例如，Ag掺杂的硫族化合物玻璃表现出极高的离子电导率。这些材料的一个有趣的转折是，在强大的外部电场下，在固体电解质中会产生电子传导路径。人们普遍猜测，通过现场驱动的电化学反应形成金属丝是导致电子电导率增强的。但是，这种观点导致了错误的预测，即金属离子和固体电解质宿主的超快速运动在外部场下同时发生。该赠款的一个假设是，外部电场产生的电子传导丝不是由金属制成，而是复杂的半导体化合物，涉及固体电解质中离子陷阱中心捕获的浓浓度离子。选择了原型金属掺杂的金属葡萄糖剂玻璃（即Ag和Cu掺杂的GE-SE和SB-TE）进行研究。采用先进的实验技术和理论技术来了解外部磁场下固体电解质的电荷和质量传输。一种称为实验约束分子弛豫（ECMR）的新型仿真技术用于确保理论与实验之间的最大重合。通过综合实验/理论方法研究了电场产生的电子传导丝的结构，性能和动力学。该项目提供了对电子传导细丝的细丝形成和结构 - 特性关系的动力学的原子见解。参加该项目的本科生和研究生接受了Argonne National Lab和俄亥俄州超级计算中心的高级光子来源和纳米级材料中心等尖端研究设施的培训。向具有自闭症谱系命令的儿童推广，以增强他们对大学教育和信息技术职业的兴趣。