arXiv subjects

Jinxing Zheng

Publications and source records attributed to Jinxing Zheng.

3 recordsLinked to original sources

arXiv2026

Colossal reversible conductivity switching by room-temperature oxygen-vacancy ordering in Aurivillius oxide films

Oxygen vacancies are central to the functionality of oxides, yet they typically exist as randomly distributed point defects, limiting the ability to precisely manipulate their collective behavior. Here, we report the room-temperature formation of a long-range-ordered oxygen-vacancy superstructure in single-crystalline Aurivillius-phase Bi2WO6 thin films via a mild nitrogen-plasma treatment. This structural transformation unlocks a colossal, reversible modulation of electrical conductivity by more than nine orders of magnitude, accompanied by a striking optical transition from transparent to black. Atomic-resolution imaging and spectroscopy reveal that the vacancies selectively order within the perovskite-like tungsten oxide layers, forming a coherent defect lattice that is absent in the pristine film. Oxygen-plasma treatment removes the vacancy superstructure and restores the initial state, whereas subsequent nitrogen-plasma treatment reconstructs it, enabling repeatable room-temperature switching between distinct structural, electronic and optical states. The phenomenon is also observed in another Aurivillius member, Bi2MoO6, suggesting its generality across the Aurivillius family. These findings establish a new paradigm for atomic-scale defect engineering - using gentle plasma chemistry to construct ordered defect lattices, opening avenues for reversible property modulation in complex oxides.

cond-mat.mtrl-sci↗

arXiv2023

A newly developed 10kA-level HTS conductor: innovative tenon-mortise-based modularized conductor (TMMC) based on China ancient architecture

We propose a new type of high temperature superconducting (HTS) conductor concept: modularized conductors (MC) connected by Chinese traditional tenon mortise (TM) connection structure, reffered as TMMC. The conductor consists of multiple concentric round sub conductors with slots for stacking REBCO tapes. Innovatively, the REBCO stacks in the adjacent sub conductors are arranged with the fully misaligned configuration to enhance the critical current' s isotropy with respect to magnetic field and reduce ac loss. For example, the angle between the adjacent stacks in the two adjacent sub conductors is 45 degree if each subconductor contains 4 REBCO stacks. In order to construct the fully misaligned configuration, the sub conductors are designed with two open half circular formers and connected by tenonmortise structure which makes the conductor modulrized and simply to assembly and disassembly. Based on the design concept, a prototype conductor containing 160 REBCO tapes distributed in the four concentric sub conductors is fabricated. The conductor measured critical current is 13.69 kA at 77 K and sefl field, which is consistent to the simulaiton result. In order to further improve the TMMC' s engineering critical current density (Jce) and bending performance, we propose two enhancement approaches which are reducing the former' s thickness and rearrange stacks in the outer sub conductors. With the enhancements, both TMMC' s radius and Jce are comparable to the existing slotted core conductor. The study shows the TMMC' s advantages of nontwisted structures, easy assembly, high current carrying and low ac losses, which makes it promising for constructing large scale scientific devices.

cond-mat.supr-con↗

arXiv2019

3D quench modeling based on T-A formulation for high temperature superconductor CORC cables

High temperature superconductor (HTS) (RE)Ba2Cu3Ox (REBCO) conductor on round core cable (CORC) has high current carrying capacity for high field magnet and power applications. In REBCO CORC cables, current redistribution occurs among tapes through terminal contact resistances when a local quench occurs. Therefore, the quench behaviour of CORC cable is different from single tape situation, for it is significantly affected by terminal contact resistances. To better understand the underlying physical process of local quenches in CORC cables, a new 3D multi-physics modelling tool for CORC cables is developed and presented in this paper. In this model, the REBCO tape is treated as a thin shell without thickness, and four models are coupled: T-formulation model, A-formulation model, a heat transfer model and an equivalent circuit model. The current redistribution, temperature and tape voltage of CORC cable during hot spot induced quenches are analysed using this model. The results show that the thermal stability of CORC cable can be considerably improved by reducing terminal contact resistance. The minimum quench energy (MQE) increases rapidly with the reduction of terminal contact resistance when the resistance is in a middle range. When the terminal contact resistance is too low or too high, the MQE shows no obvious variation with terminal contact resistances. With a low terminal contact resistance, a hot spot in one tape may induce an over-current quench on the other tapes without hot spots. This will not happen in a cable with high terminal contact resistance. In this case, the tape with hot spot will quench and burn out before inducing a quench on other tapes. The modelling tool developed can be used to design CORC cables with improved thermal stability.

cond-mat.supr-con↗