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Your search keyword '"Zhang, Rui‐Zhi"' showing total 179 results
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179 results on '"Zhang, Rui‐Zhi"'

1. Optically Detected Magnetic Resonance of Nitrogen-Vacancy Centers in Diamond under Weak Laser Excitation

Author

Yu, Yong-Hong, Zhang, Rui-Zhi, Xu, Yue, Chen, Xiu-Qi, Zheng, Huijie, Li, Quan, Liu, Ren-Bao, Pan, Xin-Yu, Budker, Dmitry, and Liu, Gang-Qin

Subjects
Quantum Physics
Abstract

As promising quantum sensors, nitrogen-vacancy (NV) centers in diamond have been widely used in frontier studies in condensed matter physics, material sciences, and life sciences. In practical applications, weak laser excitation is favorable as it reduces the side effects of laser irradiation, for example, phototoxicity and heating. Here we report a combined theoretical and experimental study of optically detected magnetic resonance (ODMR) of NV-center ensembles under weak 532-nm laser excitation. In this regime, both the width and splitting of ODMR spectra decrease with increasing laser power. This power dependence is reproduced with a model considering laser-induced charge neutralization of NV--N+ pairs, which alters the local electric field environment. These results are important for understanding and designing NV-based quantum sensing in light-sensitive applications.

Published
2023

10. Perfect valley filter based on topological phase in disordered $\rm{Sb}$ Monolayer Heterostructure

Author

Cheng, Shu-guang, Zhang, Rui-zhi, Zhou, Jiaojiao, Jiang, Hua, and Sun, Qing-Feng

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

The hydrogenated $\rm{Sb}$ monolayer epitaxially grown on a $\rm{LaFeO_3}$ substrate is a novel type of two-dimensional material hosting quantum spin-quantum anomalous Hall (QS-QAH) states. For a device formed by $\rm{Sb}$ monolayer ribbon, the QAH edge states, belong to a single valley, are located at opposite edges of the ribbon. The QSH edge states, on the other hand, belong to the other valley and are distributed in a very narrow region at the same edge. In this paper, we find such material can be used to fabricate perfect valley filter. Adopting scattering matrix method and Green's function method, the valley resolved transport and spatial distribution of local current are calculated, in the present of Anderson disorder, edge defects and edge deformations. The numerical results demonstrate that, in the presence of above three types of disorder with moderate strength, the carriers can flow disspationless with nearly perfect valley polarization. Moreover, when the device becomes longer, the transport current does not decrease while the valley filter works even better. The origin is that the disorder can destroy the QSH edge states, but the valley-polarized QAH edge states can well hold., Comment: 5 figures

Published
2017
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11. Regulating the Topology of Covalent Organic Frameworks for Boosting Overall H2O2 Photogeneration.

Author

Yue, Jie‐Yu, Luo, Jing‐Xian, Pan, Zi‐Xian, Zhang, Rui‐Zhi, Yang, Peng, Xu, Qing, and Tang, Bo

Subjects
OXIDATION-reduction reaction, TOPOLOGY, ACTIVATION energy, PHOTOREDUCTION, OXYGEN reduction, CHARGE carriers
Abstract

Photocatalytic oxygen reduction reactions and water oxidation reactions are extremely promising green approaches for massive H2O2 production. Nonetheless, constructing effective photocatalysts for H2O2 generation is critical and still challenging. Since the network topology has significant impacts on the electronic properties of two dimensional (2D) polymers, herein, for the first time, we regulated the H2O2 photosynthetic activity of 2D covalent organic frameworks (COFs) by topology. Through designing the linking sites of the monomers, we synthesized a pair of novel COFs with similar chemical components on the backbones but distinct topologies. Without sacrificial agents, TBD‐COF with cpt topology exhibited superior H2O2 photoproduction performance (6085 and 5448 μmol g−1 h−1 in O2 and air) than TBC‐COF with hcb topology through the O2‐O2⋅−‐H2O2, O2‐O2⋅−‐O21‐H2O2, and H2O‐H2O2 three paths. Further experimental and theoretical investigations confirmed that during the H2O2 photosynthetic process, the charge carrier separation efficiency, O2⋅− generation and conversion, and the energy barrier of the rate determination steps in the three channels, related to the formation of *OOH, *O21, and *OH, can be well tuned by the topology of COFs. The current study enlightens the fabrication of high‐performance photocatalysts for H2O2 production by topological structure modulation. [ABSTRACT FROM AUTHOR]

Published
2024
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20. Determining Seebeck coefficient of heavily doped La:SrTiO3 from density functional calculations

Author

Zhang, Rui-zhi, Wang, Chun-lei, Li, Ji-chao, Zhang, Jia-liang, Zhao, Ming-lei, Liu, Jian, Zheng, Peng, Zhang, Yan-fei, and Mei, Liang-mo

Subjects
Condensed Matter - Materials Science
Abstract

A new approach is developed to calculate temperature dependent Seebeck coefficient of heavily doped systems by using Boltzmann transport theory and electron density of states (DOS) obtained from density functional calculations. This approach is applied to heavily doped La:STO with DOS from tetrahedral method and Fermi energy using Fermi integrals. The calculated Seebeck coefficient agrees with the experimental data nearly quantitatively, which proved the accuracy of this approach. The influence of the Fermi energy and asymmetry of DOS on the Seebeck coefficient is analyzed., Comment: 19 pages, 4 figures

Published
2008

30. Porphyrinic Metal–Organic Framework Quantum Dots for Stable n–i–p Perovskite Solar Cells.

Author

Liu, Yinjiang, Liu, Tao, Guo, Xi, Hou, Meichen, Yuan, Yihui, Shi, Se, Wang, Hui, Zhang, Rui‐Zhi, Galiotis, Costas, and Wang, Ning

Subjects
SOLAR cells, QUANTUM dots, METAL-organic frameworks, PEROVSKITE, ION migration & velocity, LEAD halides
Abstract

As the power‐conversion efficiency (PCE) of organic–inorganic lead halide perovskite solar cells (PSCs) is approaching the theoretical maximum, the most crucial issue concerns long‐term ambient stability. Here, the application of PCN‐224 quantum dots (QDs) is reported, a typical Zr‐based porphyrinic metal–organic framework (MOF), to enhance the ambient stability of PSCs. PCN‐224 QDs with abundant Lewis‐base groups (e.g., CO, C−N, CN) contribute to high‐quality perovskite films with enlarged grain size and reduced defect density by interaction with under‐coordinated Pb2+. Meanwhile, PCN‐224 QDs enable the well‐matched energy level at the perovskite/hole transport layer (HTL) interface, thereby facilitating hole extraction and transport. More importantly, PCN‐224 QDs‐treated HTL can capture Li+ from bis(trifluoromethanesulfonyl)imide additive, leading to the reduced aggregation and less direct contact with moisture for hygroscopic Li‐TFSI. Moreover, PCN‐224 QDs mitigated Li+ ion migration into the perovskite layer, thus avoiding the formation of deleterious defects. The resultant devices yield a champion PCE of 22.51%, along with substantially improved durability, including humidity, thermal and light soaking stabilities. The findings provide a new approach toward efficient and stable PSCs by applying MOF QDs. [ABSTRACT FROM AUTHOR]

Published
2023
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37. Machine learning material properties from the periodic table using convolutional neural networks† †Electronic supplementary information (ESI) available: Training dataset analysis, training representations, training loss, predicted stable full-Heusler compounds and analysis. See DOI: 10.1039/c8sc02648c

Author

Zheng, Xiaolong, Zheng, Peng, and Zhang, Rui-Zhi

Subjects
Chemistry, Physics::Chemical Physics
Abstract

Convolutional neural networks directly learned chemical information from the periodic table to predict the enthalpy of formation and compound stability., In recent years, convolutional neural networks (CNNs) have achieved great success in image recognition and shown powerful feature extraction ability. Here we show that CNNs can learn the inner structure and chemical information in the periodic table. Using the periodic table as representation, and full-Heusler compounds in the Open Quantum Materials Database (OQMD) as training and test samples, a multi-task CNN was trained to output the lattice parameter and enthalpy of formation simultaneously. The mean prediction errors were within DFT precision, and the results were much better than those obtained using only Mendeleev numbers or a random-element-positioning table, indicating that the two-dimensional inner structure of the periodic table was learned by the CNN as useful chemical information. Transfer learning was then utilized by fine-tuning the weights previously initialized on the OQMD training set. Using compounds with formula X2YZ in the Inorganic Crystal Structure Database (ICSD) as a second training set, the stability of full-Heusler compounds was predicted by using the fine-tuned CNN, and tungsten containing compounds were identified as rarely reported but potentially stable compounds.

Published
2018

49. Ferroelectric Properties of Polycrystalline Ceramics with Dipolar Defect Simulated from the Potts-Ising Model

Author

Zhao Ming-Lei, Wang Chun-Lei, Zhang Rui-Zhi, Zhang Yan-Fei, Li Ji-Chao, Liu Jian, and Mei Liang-Mo

Subjects
Condensed Matter::Materials Science, Materials science, Condensed matter physics, Electric field, Ferroelectric ceramics, General Physics and Astronomy, Ising model, Crystallite, Coercivity, Ferroelectricity, Grain size, Potts model
Abstract

Physical properties of polycrystalline ferroelectrics including the contributions of the fixed dipolar defects and the average grain size in the Potts-Ising model are simulated by using the Monte Carlo method. Domain pattern, hysteresis loop and switching current of the polarization reversal process are obtained. Two processes are considered in our simulation. In the first one, the grain texture of ferroelectric ceramics are produced from the Potts model, and then the Ising model is implemented in the obtained polycrystalline texture to produce the domain pattern, hysteresis loop and switching current. It is concluded that the defect has the ability to decrease the remnant polarization Pr as well as the coercive field Ec. The back switching is obviously observed after the electric field is off, and it shows some variation after introducing the fixed dipolar defect. Meanwhile, the spike of the switching current is found to lower with the increasing defect concentration and the decreasing average grain size.

Published
2008

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