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Phononic Resonant Relaxation in Magnetic Hysteresis of Single-Molecule Magnets

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Chinese Physics Letters 2025年第2期 87-92页

作者： Lei Gu Jia Luo Qiancheng Luo Yuanqi Zhai yan-zhen zheng Guoping Zhao College of Physics and Electronic Engineering Sichuan Normal University Frontier Institute of Science and Technology (FIST) Xi'an Jiaotong University Center for Magnetism and Spintronics Sichuan Normal University

Lanthanide-based single-molecule magnets exhibit broad magnetic hysteresis, which manifests as slow magnetic relaxation in strong magnetic fields. However, the origin of the nontrivial hysteresis behaviors remains debated. Here, we propose two influential mechanisms: activation of optical-phonon-mediated direct transitions within the ground-state doublet and the resonant Raman process.

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Anisotropic magnetocaloric effect in a dysprosium(Ⅲ) single-molecule magnet——Commemorating the 100th anniversary of the birth of Academician Guangxian Xu

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Journal of Rare Earths 2021年第12期39卷 1554-1559,I0004页

作者： You-Song Ding yan-zhen zheng Xi'an Jiaotong University Shenzhen Research Academy Shenzhen 518057China Frontier Institute of Science and Technology Xi'an Jiaotong University

Dysprosium compounds with high magnetic anisotropy are widely studied as single molecule magnets(SMMs).Here the anisotropic magnetocaloric effect in a Dy(Ⅲ)SMM,{[Dy(OSiMe_(3))_(2)(4-Mepy)5(BPh_(4))]0.5 Toluene},was studied by single *** dependent magnetization can be observed at 300 K because of its high magnetic *** behavior measured along the easy axis direction is identical to that of the polycrystalline *** magnetization from the easy axis to the hard plane gives a maximum magnetic entropy change(-ΔSR)of 3.05 J/(kg·K)at 19 K atΔB=5 T,which enables the Dy(Ⅲ)SMM to be used as a low-temperature rotating magnetic refrigerant.

关键词： Lanthanide complex Magnetic anisotropy Rotate magnetocaloric effect Single molecule magnets Rare earths

A novel mathematical model for coverage in wireless sensor network

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The Journal of China Universities of Posts and Telecommunications 2006年第4期13卷 67-72页

作者： yan zhen-ya zheng Bao-yu Institute of Signal and Information Processing Nanjing University of Posts and Telecommunications Nanjing 210003 China

Coverage problem is one of the fundamental issues in the design of wireless sensor network, which has a great impact on the performance of sensor network. In this article, coverage problem was investigated using a mathematical model named Birth-death process. In this model, sensor nodes joining into networks at every period of time is considered as the rebirth of network and the quitting of sensor nodes from the networks is considered as the death of the network. In the end, an analytical solution is used to investigate the appropriate rate to meet the coverage requirement.

关键词： wireless sensor networks Ad-hoc birth-death coverage

Analysis of the optical quality by determining the modulation transfer function for anterior corneal surface in myopes

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International Journal of Ophthalmology(English edition) 2012年第2期5卷 196-201页

作者： yan-zhen zheng, Yao-Yu Li Department of Ophthalmology General Hospital of Beijing Military Command of Chinese PLA Beijing 100700 China Shanxi Medical University Taiyuan 030001 Shanxi Province China

AIM: To describe the characteristics of modulation transfer function (MTF) of anterior corneal surface, and obtain the the normal reference range of MTF at different spatial frequencies and optical zones of the anterior corneal surface in myopes. METHODS: Four hundred eyes from 200 patients were examined under SIRIUS corneal topography system. Phoenis analysis software was applied to simulate the MTF curves of anterior corneal surface at vertical and horizontal meridians at the 3, 4, 5, 6, 7mm optical zones of cornea. The MTF values at spatial frequencies of 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 and 60 cycles/degree (c/d) were selected. RESULTS: The MTF curve of anterior corneal surface decreased rapidly from low to intermediate frequency (0-15cpd) at various optical zones of cornea, the value decreased to 0 slowly at higher frequency (>15cpd). With the increase of the optical zones of cornea, MTF curve decreased gradually. 3) In the range of 3 mm- 6 mm optical zones of the cornea, the MTF values measured at horizontal meridian were greater than the corresponding values at horizontal meridian of each spatial frequency, the difference was statistically significant (P<0.05). At 7 mm optical zones of cornea, the MTF values measured at horizontal meridian were less than the corresponding values at vertical meridian at 10-60 spatial frequencies (cpd), and the difference was statistically significant in 25, 30, 35, 40, 45, 50 cpd(P<0.05). CONCLUSION: MTF can be used to describe the imaging quality of optical systems at anterior corneal surface objectively in detail.

关键词： modulation transfer function optical quality cornea point spread function optical transfer function phase transfer function

2D/2D heterostructured MoS_(2)/PtSe_(2) promoting charge separation in FTO thin film for efficient and stable photocatalytic hydrogen evolution

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Rare Metals 2022年第5期41卷 1735-1742页

作者： Shu-Tong Wan Hao-Tong Li zhen-Hui Ma He-Chuan Zhang yan-zhen zheng Beijing Key Laboratory of Green Recovery and Extraction of Rare and Precious Metals University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China Department of Physics Beijing Technology and Business UniversityBeijing 100037China

Exploiting stable photocatalytic films is of practical significance for solar energy-hydrogen conversion and pollutant degradation, yet remains a big challenge so far. In this work, we report a highly stable photocatalytic film, i.e.,MoS_(2)/PtSe_(2)/FTO by sequential growing PtSe_(2) and MoS_(2) onto commercially fluorine-doped tin oxide(FTO) substrates using two round thermal evaporation and chemical vapor deposition(CVD) process.

关键词： film FTO separation

Enhancing blocking temperature using inverse hydrogen bonds for non-radical bridged dimeric Dy(Ⅲ)single-molecule magnets

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Science China Chemistry 2024年第10期67卷 3328-3338页

作者： Peng-Bo Jin Qian-Cheng Luo Ye-Ye Liu yan-zhen zheng Frontier Institute of Science and Technology State Key Laboratory of Electrical Insulation and Power EquipmentMOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed MatterXi’an Key Laboratory of Electronic Devices and Material Chemistry and School of ChemistryXi’an Jiaotong UniversityXi’an 710054China

Single-molecule magnets(SMMs)are a kind of nanosized magnetic materials that are capable of storing massive bytes of *** coupling the spin centers in a proper manner is a usual approach to promote the working temperature(or blocking temperature)for *** delocalized radicals have been widely employed to accomplish this ***,we show a new manner by using weak but multiple B–H^(δ-)···Dy^(3+)inverse hydrogen bonding(IHB)interactions to control the magnetic couplings in a series of dimeric dysprosiacaborane *** approach leads to a record high T_(B)^(100s)of 10 K among non-radical bridged dimeric SMMs,which is mainly ascribed to strong ferromagnetic coupling(4.38 cm^(-1))and the proper alignment of the magnetic principle axes of the adjacent dysprosium(Ⅲ)*** verifying by theoretical calculations,these results demonstrate that IHB interactions can be used to construct strong axial ferromagnetic coupling and enhancing magnetic blocking temperature for SMMs.

关键词： single-molecule magnets carborane dysprosium ferromagnetic coupling inverse hydrogen bond

Trimethyl phosphate-enhanced polyvinyl carbonate polymer electrolyte with improved interfacial stability for solid-state lithium battery

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Rare Metals 2022年第6期41卷 1889-1898页

作者： Fei zheng Hao-Tong Li yan-zhen zheng Dan Wang Ning-Ning yang Hai-yang Ding Xia Tao Beijing Key Laboratory of Green Recovery and Extractionof Rare and Precious Metals University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China General Research Institute of Nonferrous Metals Beijing 100088China China Automotive Battery Research Institute Co. Ltd.Beijing 101407China

The polyvinyl carbonate(PVC)polymer solid electrolyte can be in-situ generated in the assembled lithium-ion battery(LIBs);however,its rigid characteristic leads to uneven interface contact between electrolyte and *** this work,trimethyl phosphate(TMP)is introduced into the precursor solution for in-situ generation of flexible PVC solid electrolyte to improve the interfacial contact of elec-trolyte and electrodes together with ionic *** PVC-TMP electrolyte exhibits good interface compatibility with the lithium metal anode,and the lithium symmetric battery based on PVC-TMP electrolyte shows no obvious polarization within 1000 h *** a consequence,the initial interfacial resistance of battery greatly decreases from 278Ω(LiFePO_(4)(LFP)/PVC/Li)to 93Ω(LFP/PVC-TMP/Li)at 50℃,leading to an improved cycling stability of the LFP/PVC-TMP/Li *** in-situ preparation of solid electrolyte within the battery is demonstrated to be very significant for commercial application.

关键词： Trimethyl phosphate Solid polymer electrolyte Interface stability Compatibility Lithium ion battery

Gd-based molecular coolants:Aggregating for better magnetocaloric effect

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Aggregate 2024年第4期5卷 126-139页

作者： Yuan-Qi Zhai Wei-Peng Chen Marco Evangelisti zhendong Fu yan-zhen zheng Department of Hepatobiliary Surgery Institute of Advanced Surgical Technology and EngineeringThe First Affiliated Hospital of Xi’an Jiaotong UniversityXi’anShaanxiP.R.China Frontier Institute of Science and Technology Xi’an Key Laboratory of Electronic Devices and Materials ChemistrySchool of ChemistryXi’an Jiaotong UniversityXi’anShaanxiP.R.China Instituto de Nanociencia y Materiales de Aragón CSIC&Universidad de ZaragozaZaragozaSpain Songshan Lake Materials Laboratory DongguanP.R.China

Two series of 3d-Gd mixed-metal phosphonate complexes with either only two gadolinium centers such as{Gd_(2)},{Ni_(2)Gd_(2)},{Co_(4)Gd_(2)},{Co_(8)Gd_(2)},{Fe_(6)Gd_(2)},and{Fe_(17)Gd_(2)}or more than two gadoliniums such as{Co_(8)Gd_(4)},{Mn_(8)Gd_(4)},{Co_(4)Gd_(6)},{Mn_(4)Gd_(6)},{Co_(6)Gd_(8)},{Ni_(5)Gd_(8)},{Ni_(6)Gd_(6)},{Co_(8)Gd_(8)},and{Mn_(9)Gd_(9)}have been solvothermally prepared and magnetothermally *** nearly identical environments of the Gd(III)dimer in thefirst series allow us to qualitatively analyze the effect of magnetic exchange coupling on the magne-tocaloric effect(MCE).By doubling,tripling,or quadrupling of the Gd(III)centers,the second series of 3d-Gd mixed-metal complexes was built to further test the other effects of exchange couplings on MCE in more complicated *** the antiferromagnetic coupling cases,the results are nearly identical but diversify when topological spin frustrations are created,whose massive low-lying excited spin states help enhance *** presumably ferromagnetically coupled ones,albeit are rare in phosphonate complexes,they do exhibit excellent ***,the com-plexes with weakly coupled metal centers serve as excellent examples for studying the effect of molecular mass on MCE when its magnitude is expressed in the unit of Joule per kilogram,from which we can see the values are directly proportional to the percentage of the Gd(III)ions in molecular weight.

关键词： 3d-4f lanthanide magnetocaloric effect phosphonate refrigerant

Strong Antiferromagnetic Exchange-Coupling Observed in Hydride-Bridged Dimeric Dysprosium(Ⅲ)Single-Molecule Magnet

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Chinese Journal of Chemistry 2024年第4期42卷 391-396页

作者： Qian-Cheng Luo Ke-Xin Yu Peng-Bo Jin Ye-Ye Liu Yuan-Qi Zhai yan-zhen zheng Frontier Institute of Science and Technology State Key Laboratory of Electrical Insulation and Power EquipmentXi'an Key Laboratory of Electronic Devices and Materials ChemistrySchool of Chemistry and School of PhysicsXi'an Jiaotong University99 Yanxiang RoadXi'anShaanxi710054 China

One dihydride-bridged dimeric Dy(Ⅲ)guanidinate complex,formulated as[{(Me_(3)Si)_(2)NC(NiPr)_(2)}_(2)Dy(μ-H)]_(2)(1Dy),was successfully isolated and the introduction of hydride bridges significantly reduces the intramolecular Dy(Ⅲ)…Dy(Ⅲ)distance to only 3.688(1)Å.To investigate the effect of such a short Dy(Ⅲ)…Dy(Ⅲ)distance on magnetism,we also prepared its dibromide-bridged analogue[{(Me_(3)Si)_(2)NC(NiPr)_(2)}_(2)Dy(μ-Br)]_(2)(2Dy),which has a much longer Dy(Ⅲ)…Dy(Ⅲ)distance of 4.605(4)Å.Surprisingly,2Dy demonstrates much larger effective energy barrier for magnetization reversal(U_(eff))and higher blocking temperature(T_(B)).The worse performance of 1Dy is attributed to the concerted effect of strong antiferromagnetic interactions between Dy(Ⅲ)ions(J_(total)=–2.683 cm^(–1))and the unparallel arrangement of magnetic principle axes of the Dy(Ⅲ)ions for 1Dy.

关键词： Single-molecule magnets Lanthanides Guanidinate ligand Hydride bridge Magnetic properties Ab initio calculations