arXiv subjects

Jiajian Guan

Publications and source records attributed to Jiajian Guan.

3 recordsLinked to original sources

arXiv2024

Elucidating the thermal spike effect by using a coupled classical oscillator model

Atomic heating is a fundamental phenomenon governed by the thermal spike effect during energetic deposition. This work presented another insight into thermal spike using a coupled classical oscillator model instead of a typical heat diffusion model. The temperature profile of deposited atoms was replaced by oscillator amplitude as an energy descriptor. Solving associated partial differential equations (PDEs)suggests the efficiency of energy transfer from the coupled hot to cold oscillators essentially relies on the atomic distance r and the spring constant k. The solution towards the damped wave equation further emphasize that a localized thermal fluctuation during energy propagation.

physics.comp-ph↗

arXiv2023

Understanding binary phase separation towards Cu-C nanocrystalline-amorphous composites

The nanocrystalline-amorphous textures are commonly observed in the coatings synthesized by energetic deposition.This work reports a theoretical study towards binary Cu-C phase separation.By performing a MD simulation using the LAMMPS instead of classical PFK methodology, we theoretically explained how the initial pressure and Cu concentration fundamentally determines Cu nanocrystalline's final morphology and grain size,which gives a novel insight into binary phase separation and the evolution mechanism of nanocrystalline-amorphous structures during energetic deposition.

cond-mat.mtrl-sci↗

arXiv2023

Unravelling the deterministic effect of the solid-state diffusion energy barrier for charge carrier on the self-discharge of supercapacitors

The further development of fast electrochemical devices is hindered by self-discharge. Current strategies for suppressing self-discharge are mainly focused on the extrinsic and general mechanisms including faradaic reactions, charge redistribution, and ohmic leakage. However, the self-discharge process is still severe for conventional supercapacitors. Herein, we unravel the deterministic effect of solid-state diffusion energy barrier by constructing conjugately configured supercapacitors based on pairs of pre-lithiated niobium oxides with similar intercalation pseudocapacitive process but different phases. This device works with a single type of charge carrier while materials with various diffusion barriers can be implanted, thus serving as an ideal platform to illustrate the influence of the diffusion barrier. The results show that the comprehensive effect of solid-state diffusion energy barrier and extrinsic effects drives the self-discharge process. Noteworthy, the diffusion barrier presents with an exponential form, which governs the self-discharge of supercapacitors. This work is expected to unravel the deterministic effect of the solid-state diffusion energy barrier and provide a general guidance for suppressing self-discharge for supercapacitors.

physics.chem-ph↗