“Resistive switching in Ag₂Te semiconductor modulated by Ag+-ion diffusion and phase transition”. Guo A, Bai H, Liang Q, Feng L, Su X, Van Tendeloo G, Wu J, Advanced Electronic Materials , 2200850 (2022). http://doi.org/10.1002/AELM.202200850
Abstract: Memristors are considered to be the fourth circuit element and have great potential in areas like logic operations, information storage, and neuromorphic computing. The functional material in a memristor, which has a nonlinear resistance, is the key component to be developed. Herein, resistive switching is demonstrated and the structural evolutions in Ag2Te are examined under an external electric field. It is shown that the electroresistance effect is originating from an electronically triggered phase transition together with directional Ag+-ion diffusion. Using in situ transmission electron microscopy, the phase transition from the monoclinic alpha-Ag2Te into the face-centered cubic beta-Ag2Te, accompanied by a change in resistance, is directly observed. Diffusion of Ag+-ions modulates the localized density of Ag+-ion vacancies, leading to a change in electrical conductivity and influences the threshold voltage to trigger the phase transition. During the electric field-driven phase transition, the spontaneous and localized multiple polarizations from the low-symmetry alpha-Ag2Te (referring to an antiferroelectric structure) are vanishing in the cubic beta-Ag2Te (referring to a paraelectric structure). The abrupt resistance change of thin Ag2Te caused by the phase transition and modulated by the applied electric field demonstrates its great potential as functional material in volatile memory and memristors with a low-energy consumption.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 6.2
DOI: 10.1002/AELM.202200850
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“Phase-transformation-induced giant deformation in thermoelectric Ag₂Se semiconductor”. Liang Q, Yang D, Xia F, Bai H, Peng H, Yu R, Yan Y, He D, Cao S, Van Tendeloo G, Li G, Zhang Q, Tang X, Wu J, Advanced Functional Materials , 2106938 (2021). http://doi.org/10.1002/ADFM.202106938
Abstract: In most semiconducting metal chalcogenides, a large deformation is usually accompanied by a phase transformation, while the deformation mechanism remains largely unexplored. Herein, a phase-transformation-induced deformation in Ag2Se is investigated by in situ transmission electron microscopy, and a new ordered high-temperature phase (named as alpha '-Ag2Se) is identified. The Se-Se bonds are folded when the Ag+-ion vacancies are ordered and become stretched when these vacancies are disordered. Such a stretch/fold of the Se-Se bonds enables a fast and large deformation occurring during the phase transition. Meanwhile, the different Se-Se bonding states in alpha-, alpha '-, beta-Ag2Se phases lead to the formation of a large number of nanoslabs and the high concentration of dislocations at the interface, which flexibly accommodate the strain caused by the phase transformation. This study reveals the atomic mechanism of the deformation in Ag2Se inorganic semiconductors during the phase transition, which also provides inspiration for understanding the phase transition process in other functional materials.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.124
DOI: 10.1002/ADFM.202106938
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“A universal synthesis strategy for single atom dispersed cobalt/metal clusters heterostructure boosting hydrogen evolution catalysis at all pH values”. Yuan S, Pu Z, Zhou H, Yu J, Amiinu IS, Zhu J, Liang Q, Yang J, He D, Hu Z, Van Tendeloo G, Mu S, Nano energy 59, 472 (2019). http://doi.org/10.1016/J.NANOEN.2019.02.062
Abstract: The development of a stable, efficient and economic catalyst for hydrogen evolution reaction (HER) of water splitting is one of the most hopeful approaches to confront the environmental and energy crisis. A two-step method is employed to obtain metal clusters (Ru, N, Pd etc.) combining single cobalt atoms anchored on nitrogen-doped carbon (Ru/Pt/Pd@Co-SAs/N-C). Based on the synergistic effect between Ru clusters and single cobalt atoms, Ru@Co-SAs/N-C exhibits an outstanding HER electrocatalytic activity. Specifically, Ru@Co-SAs/N-C only needs 7 mV overpotential at 10 mA cm(-2) in 1 M KOH solution, which is much better than commercial 20 wt% PVC (40 mV) catalyst. Density functional theory (DFT) calculations further reveal the synergy effect between surface Ru nanoclusters and Co-SAs/N-C toward hydrogen adsorption for HER. Additionally, Ru@CoSAs/N-C also exhibits excellent catalytic ability and durability under acidic and neutral media. The present study opens a new avenue towards the design of metal clusters/single cobalt atoms heterostructures with outstanding performance toward HER and beyond.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.343
Times cited: 33
DOI: 10.1016/J.NANOEN.2019.02.062
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