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Thermo-optical properties of luminescent carbon dots produced from biomass of Orbignya speciosa (babassu coconut)

Journal of Molecular Liquids 2025年 423卷

作者： Oliveira, Maykol Christian Damasceno Silva, Adriano Almeida Silva-Silva, Tânia Patrícia Silva, Jhaemely Gabrielly Vieira da Silva Júnior, José Ferreira Sanchez, David Bell, Maria José Valenzuela Garcia, Hans Anderson Viana, Bartolomeu Cruz Terrones, Mauricio Costa, Rubens Silva Santos, Francisco Eroni Paz Physics Department Federal University of Piauí PI 64049550 Brazil Postgraduate Program in Engineering and Materials Science Federal University of 64049550 PI Teresina Brazil Department of Physics and Center for 2-Dimensional and Layered Materials The Pennsylvania State University University ParkPA16802 United States Federal University of Juiz de Fora Institute of Exact Sciences Department of Physics University Campus - UFJF/ ICE/ Department of Physics Martelos MG Juiz de Fora36036330 Brazil Federal Institute of Piauí Paranaíba Campus PI Parnaíba64211145 Brazil

Exploring materials with high nonlinearities derived from organic and biological sources has become a significant focus within the scientific community. Among these materials, carbon dots (CDs) synthesized from biomass have emerged as promising candidates due to their sustainable and cost-effective production methods. This study synthesized CDs from Orbignya speciosa (babassu coconut) biomass via a hydrothermal route. UV–visible absorption and Infrared spectrum analysis revealed characteristic bands associated with the formation of dots and the electronic transitions π–π* from aromatic C=C bonds in the CDs’ core and n–π* transitions of surface carboxylate groups, photoluminescence as a function of temperature and lifetime decay measurements show that the photoluminescence mechanisms in these materials due this transitions comes from electronic indirect transitions from primary sources of the core and carbonyl boundings in the surface of the material, additionally, to this the Dynamic Light Scattering (DLS) and Transmission Electronic Microscopy (TEM) give the structural properties of the dots, amorphous and with a large size distribution with a mean size of (21 ± 1) nm. Thermal lens spectroscopy (TLS) was employed to determine the material's thermal diffusivity, reaching a maximum value of 2.03 × 10−7 m2/s as a function of dilution. The Z-scan technique under continuous wave (CW) excitation at 532 nm investigated nonlinear optical properties, yielding a maximum thermal nonlinear refractive index (n2(th)) value of −5.87 × 10−5 esu. Furthermore, the photothermal efficiency of the CDs was quantified at 505 nm, demonstrating a high absorption efficiency of 94.9 %, suggesting their potential application in photothermal therapies. These findings contribute to understanding babassu coconut CDs’ thermo-optical behavior, highlighting their promise for various practical applications, particularly in biomedicine. © 2025 Elsevier B.V.

关键词： Refractive index

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Correlation versus dissipation in a non-Hermitian Anderson impurity model

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Physical Review B 2025年第12期111卷 125157-125157页

作者： Kazuki Yamamoto Masaya Nakagawa Norio Kawakami Department of Physics Tokyo Institute of Technology Meguro Tokyo 152-8551 Japan Department of Physics University of Tokyo Hongo Tokyo 113-0033 Japan Fundamental Quantum Science Program TRIP Headquarters RIKEN Wako 351-0198 Japan Department of Physics Ritsumeikan University Kusatsu Shiga 525-8577 Japan Department of Materials Engineering Science Osaka University Toyonaka Osaka 560-8531 Japan

We analyze the competition between strong correlations and dissipation in quantum impurity systems from the Kondo regime to the valence fluctuation regime by developing a slave-boson theory for a non-Hermitian Anderson impurity model with one-body loss. Notably, in the non-Hermitian Kondo regime, strong correlations qualitatively change the nature of dissipation through renormalization effects, where the effective one-body loss is suppressed and emergent many-body dissipation characterized by the complex-valued hybridization is generated. We unveil the mechanism of a dissipative quantum phase transition of the Kondo state on the basis of this renormalization effect, which counterintuitively enhances the lifetime of the impurity against loss. We also find a crossover from the non-Hermitian Kondo regime to the valence fluctuation regime dominated by one-body dissipation. Our results can be tested in a wide variety of setups such as quantum dots coupled to electronic leads and quantum point contacts in ultracold Fermi gases.

关键词： Bosons

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Development of Flexible Sendust Composite Sheets with Enhanced Magnetic Permeability for Microwave Absorbers and Antennas

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IEEE Transactions on Magnetics 2025年

作者： Whalen, Matthew P. Plouff, David T. Shevchenko, Nicholas B. Mirotznik, Mark Xiao, John Q. University of Delaware Quantum Science and Engineering Program NewarkDE19716 United States University of Delaware Department of Physics and Astronomy NewarkDE19716 United States University of Delaware Center for Composite Materials NewarkDE19716 United States University of Delaware Department of Electrical and Computer Engineering NewarkDE19716 United States

The demand for high-frequency soft magnetic composites with elevated permeability and flexibility is growing for applications in microwave absorbers and magnetodielectric antennas. However, balancing high permeability with mechanical flexibility remains challenging. This study presents flexible Sendust (FeSiAl) composite sheets, fabricated with a hot-pressing technique that aligns flakes within an acrylic rubber and epoxy resin matrix. The alignment significantly enhances relative permeability at high frequencies, achieving single-layer film properties of μr' = 14.8 and μr"= 20.4 at 1 GHz, alongside high saturation magnetization (118 eμg) and high hesitivity (44.7 kΩ m-1), outperforming commonly used materials such as NiZn ferrite. Our method supports customizable thickness without sacrificing permeability, establishing a versatile platform for advanced conformal microwave absorber and antenna applications. © 2025 IEEE.

关键词： Saturation magnetization

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Nonsaturated large magnetoresistance and transport dynamics in a n-doped cryogenic WSe2 field-effect device

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Physical Review B 2025年第12期111卷 125307-125307页

作者： Wei-Chen Lin Ching-Chen Yeh Jia-Zhu Zou Nhat Anh Nguyen Phan Inayat Uddin Hai Yen Le Thi Kenji Watanabe Takashi Taniguchi Gil-Ho Kim Department of Engineering and System Science National Tsing Hua University Hsinchu 300 Taiwan Taiwan International Graduate Program Academia Sinica Taipei 115 Taiwan Department of Physics National Taiwan University Taipei 106 Taiwan Department of Electrical and Computer Engineering Sungkyunkwan University (SKKU) Suwon 164 Republic of Korea Sungkyunkwan Advanced Institute of Nano Technology (SAINT) Sungkyunkwan University (SKKU) Suwon 16419 Republic of Korea Research Center for Electronic and Optical Materials National Institute for Materials Science 1-1 Namiki Tsukuba 305-0044 Japan Research Center for Materials Nanoarchitectonics National Institute for Materials Science 1-1 Namiki Tsukuba 305-0044 Japan

Interest in the two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs) continues to intensify, driven by their suitable band gaps to supplant silicon as next-generation semiconductor materials. Among various TMDs, tungsten diselenide (WSe2) is renowned for its superior electrical properties in carrier density and mobility under ambient conditions. Despite its notable attributes, the behavior of monolayer WSe2 in the electron-doped regime under cryogenic conditions remains largely uncharted, particularly concerning its magnetotransport properties. In this study, we reveal the transport mechanisms of monolayer WSe2 from high temperatures down to the cryogenic regime. As evident by Efros–Shklovskii variable-range hopping (E-S VRH) in the cryogenic regime, strong Coulomb interactions arise between electrons. Above 8 K, an uncommon nonsaturated quadratic large magnetoresistance (MR) can be explained by the wave-function shrinkage model, which is consistent with the E-S VRH transport mechanism. Notably, the nonsaturated quadratic large MR shows a magnitude up to 1740% at 13 T. These findings underscore the potential applications for monolayer WSe2 in cryogenic field-effect devices, magnetic sensors, and memory devices and mark a significant advance in magnetotransport research.

关键词： Monolayers

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Natural Alkaloids (Caffeine, Theobromine and Theophylline) as Dielectric Capping Layers for Gold and Aluminum Gate Electrodes in Low Operating Voltage Organic Field-Effect Transistors

IEEE Journal on Flexible Electronics

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IEEE Journal on Flexible Electronics 2025年

作者： Irimia, Cristian Vlad Yumusak, Cigdem Ban, Boyuan Leeb, Elisabeth Mayr, Felix Schimanofsky, Corina Mardare, Andrei Ionut Molnar, Maximilian Alexander Teichert, Christian Sariciftci, Niyazi Serdar Irimia-Vladu, Mihai Institute of Physical Chemistry Altenberger Str. 69 Linz4040 Austria Graz University of Technology in Graz Master of Science student in Advanced Materials Science program Austria Montanuniversität Leoben Chair of Physics Department of Physics Mechanics and Electrical Engineering Franz Josef Str. 18 Leoben8700 Austria Key Lab of Photovoltaic and Energy Conservation Materials Institute of Solid-State Physics Hefei Institute of Physical Science Hefei230031 China Altenberger Str. 69 Linz4040 Austria National Institute for Lasers Plasma and Radiation Physics Magurele077125 Romania

Three natural alkaloids: caffeine, theobromine and theophylline are reported for their application as dielectric layers in organic field effect transistors (OFETs) utilizing both gold and aluminum gate electrodes. After careful purification of the materials, a detailed analysis using x-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), contact angle (CA), impedance spectroscopy, amplitude modulated kelvin probe force microscope (AM-KPFM) and cyclic voltammetry (CV) is performed. OFET devices operating at typical voltages between 2 and 4 V have been fabricated with the investigated alkaloid films processed via blade coating (caffeine) or vacuum processing (theobromine and theophylline). The dielectric properties of these three alkaloids are measured in impedance spectroscopy and negligible leakage currents are observed when deposited in thin films as dielectric layers in OFETs on aluminum electrodes. There is a high tendency of these molecules to crystallize and form uneven surfaces. When the thin film forming properties are carefully controlled, organic alkaloids can be employed in applications involving implantable, transient or even edible electronics. © 2022 IEEE.

关键词： Fourier transform infrared spectroscopy

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Phonon dynamics and magnetodielectric relaxation in distorted honeycomb ferrimagnet Ni4Nb2O9: Experiment and first-principles study

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Physical Review materials 2025年第4期9卷 045202-045202页

作者： Harshita Singh Sobhit Singh Sayandeep Ghosh Prativa Pramanik Vasant Sathe Roland Mathieu Wilfrid Prellier Subhash Thota Department of Physics Indian Institute of Technology Guwahati Assam 781039 India Department of Mechanical Engineering University of Rochester Rochester New York 14627 USA Materials Science Program University of Rochester Rochester New York 14627 USA Department of Physics Chungnam National University Daejeon 34134 Republic of Korea Department of Physics Kunsan National University Gunsan 54150 Republic of Korea Department of Materials Science and Engineering Uppsala University Uppsala SE-75103 Sweden UGC DAE Consortium for Scientific Research Indore 452 001 India Laboratoire CRISMAT ENSICAEN CNRS Université de Caen Normandie Université Caen France

We present the experimental and theoretical studies of lattice dynamics, electronic structure, and magnetodielectric relaxation in the ferrimagnetic (FiM) Ni4Nb2O9. This system exhibits a distorted honeycomb lattice with the space group Pbcn (no. 60) and undergoes FiM ordering below 76 K (TFN), accompanied by a magnetic compensation at 33 K (TCOM). By employing density-functional theory (DFT+U) calculations and vibrational spectroscopy, we study all the allowed Raman and infrared phonon modes in Ni4Nb2O9. Temperature-dependent analysis of Raman-active phonon frequencies provides evidence of spin-phonon coupling in Ni4Nb2O9. Interestingly, we observe a nonlinear mode softening phenomenon in both frequencies ω(T) and their linewidths δωF(T), which can be described using three-phonon anharmonic processes. Contrary to the behavior of the remaining modes, 510 cm−1 mode shows a blue shift and effectively acts as a breathing mode for Ni atoms of two sublattices, and hence plays a crucial role in stabilizing the FiM ground state, thus explaining the strong sensitivity of this Ag mode to temperature. Our investigation of the temperature- and field-dependent relative dielectric permittivity and loss-tangent data reveals the absence of magnetodielectric coupling and the presence of dipole relaxation behavior in Ni4Nb2O9. Additionally, the theoretically determined indirect band gap is about 2.7 eV. Overall, our study helps to fill the existing knowledge gap and provides valuable insights into the electronic, vibrational, and magnetodielectric properties of Ni4Nb2O9, shedding light on its potential applications in dielectric-ceramic resonators and electrochemical sensors.

关键词： Local density approximation

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Early and advanced crystallization stages in lithia-alumina-silica glasses nucleated by ZrO2

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Ceramics International 2025年

作者： Revelo, Raúl Julián Souza, Mauricio Lima Pena, Rafaella Bartz Yoshida, Satoshi Zanotto, Edgar Dutra Federal University of São Carlos Graduate Program in Materials Science and Engineering SP São Carlos13565-905 Brazil São Carlos Institute of Physics University of São Paulo SP São Carlos13566-590 Brazil Materials Integration Laboratories AGC Inc 1-1 Suehiro-Cho Tsurumi-Ku Kanagawa Yokohama230-0045 Japan

ZrO2 is one of the most effective and widely used nucleating agents in various families of glass-ceramics;however, its detailed mechanism remains a subject of debate. Understanding its nucleation mechanism requires a thorough analysis of microstructural evolution and the identification of factors influencing this process. This study investigates the effects of ZrO2 incorporation on the internal nucleation and microstructural evolution in stoichiometric LAS (Li2O·Al2O3·nSiO2) glass-ceramics of varying composition. Glasses with different SiO2 molar ratios (n = 2, 4, 5, and 6) were prepared with ZrO2 additions of 3.0 and 3.5 mol%. Several thermal treatments were employed, followed by characterization using XRD, SEM, STEM, and Raman spectroscopy. The results indicate that a minimum of 3.5 mol% ZrO2 is required to induce internal nucleation in LAS glasses with n = 4, 5, and 6. In these compositions, Zr-enriched regions formed through liquid-liquid phase separation serve as preferential sites for ZrO2 crystal precipitation, which subsequently induces the nucleation of β-quartz solid solution. Upon further treatment at higher temperatures, this metastable phase transforms into β-spodumene or its solid solution. As expected, increasing SiO2 content enhances glass network polymerization, as evidenced by the increased presence of Q3 species in Raman spectroscopy, leading to higher characteristic temperatures of glass transition and peak crystallization in DSC analyses. A higher SiO2 content results in fewer but larger crystals, whereas a lower SiO2 content promotes a higher number density of crystals within the glass matrix. © 2025 Elsevier Ltd and Techna Group S.r.l.

关键词： Glass ceramics

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High-Performance Al–S Batteries by Spin Polarization Modulation via Catalytic Ni-MoS₂ Nanosheets

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Angewandte Chemie - International Edition 2025年 e202503835页

作者： Liu, Xiaoya Liu, Xingjun Zhan, Jiqiang Yuan, Wang Zhu, Yue Huang, Weiyuan Li, Hongpeng Liu, Tongchao Amine, Khalil Li, Hongsen Yu, Guihua College of Physics Qingdao University Qingdao 266071 China Materials Science and Engineering Program and Walker Department of Mechanical Engineering The University of Texas at Austin Austin 78712 TX United States School of Materials Science and Engineering Ocean University of China Qingdao 266404 China Chemical Science and Engineering Division Argonne National Laboratory Lemont 60439 IL United States College of Mechanical Engineering Yangzhou University Yangzhou 225127 China

Aluminum–sulfur (Al–S) batteries catalysts with adsorption and catalytic capabilities can effectively improve the slow redox kinetics, but the current research often ignores the effect of optimizing the electronic structure of the catalyst on improving charge transfer and adsorption. Here, Ni-doped monolayer MoS₂ nanosheets are synthesized and used as a catalytic additive for the sulfur cathode. The addition of Ni promotes spin splitting of 4d orbital of Mo, thereby affecting polarization degree of the basal plane sulfur and making it change from a low spin state to a high spin one. This high spin configuration raises the electron energy level and provides an active electron state to react with aluminum polysulfides (AlPSs), which optimizes the adsorption energy. At the same time, it accelerates electron transfer and lowers the energy barrier for the overall conversion of the polysulfides. Benefiting from these features, Al–S batteries based on rationally designed S@Ni-MoS₂/C cathodes exhibit a high initial capacity (1603.0 mAh g⁻¹ at 0.5 A g⁻¹) and extraordinary cycling stability (0.035% capacity decay rate during 2000 cycles). This study showcases a spin-polarized electronic structure control strategy to enhance catalytic activity, providing a viable approach for developing efficient catalysts for practical Al–S batteries. © 2025 Wiley-VCH GmbH.

关键词： Aluminum–sulfur batteries Catalyst Electronic structure control Ni-doped monolayer MoS2 nanosheets

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Change in Magnetic Order in NiPS3 Single Crystals Induced by a Molecular Intercalation

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Chemistry of materials 2025年第10期37卷 3594-3607页

作者： Chakraborty, Nirman Harchol, Adi Arnold, Beatriz Costa Sharma, Kusha Prabhu Gaonkar, Diksha Abu-Hariri, Azhar Yadav, Rajesh Kumar Dawod, Muhamed Eyal, Anna Amouyal, Yaron Brumme, Thomas Heine, Thomas Naveh, Doron Lifshitz, Efrat Schulich Faculty of Chemistry Solid State Institute Russel Berrie Nanotechnology Institute Grand Program for Energy and the Helen Diller Quantum Center Technion-Israel Institute of Technology Haifa3200003 Israel Helmholtz-Zentrum Dresden-Rossendorf Bautzner Landstr. 400 Dresden01328 Germany Center for Advanced Systems Understanding CASUS Untermarkt 20 Gorlitz02826 Germany Faculty of Engineering Bar-Ilan University Ramat-Gan5290002 Israel Institute of Nanotechnology and Advanced Materials Bar-Ilan University Ramat-Gan5290002 Israel Department of Materials Science and Engineering Technion-Israel Institute of Technology Haifa3200003 Israel Department of Physics Technion Haifa3200003 Israel Department of Theoretical Chemistry Technische Universität Dresden Bergstrasse 66 Dresden01069 Germany Yonsei University and ibs-cnm Seoul120-749 Korea Republic of

Intercalation is a robust method for tuning the physical properties of a vast number of van der Waals (vdW) materials. However, the prospects of using intercalation to modify magnetism in van der Waals (vdW) systems and the associated mechanisms have not been adequately studied. In this work, we modulated magnetic order in XY antiferromagnet NiPS3 single crystals by introducing pyridine molecules into the vdW’s gap under different thermal conditions. X-ray diffraction measurements indicated pronounced changes in the lattice parameter β, while magnetization measurements at in-plane and out-of-plane configurations exposed reversal trends in the crystals’ Néel temperatures through intercalation/deintercalation processes. The changes in magnetic ordering were also supported by three-dimensional thermal diffusivity experiments. The preferred orientation of the pyridine dipoles within the vdW gaps was deciphered via polarized Raman spectroscopy. The results highlighted the relationship between the preferential alignment of the intercalants, thermal transport, and crystallographic disorder, along with the modulation of anisotropy in the magnetic order. DFT + U calculations indicated that the varying interlayer exchange interactions, regulated by intercalants, were responsible for modulating samples’ magnetic ordering. The study uncovers the possible merit of intercalation for manipulating spin orientations in spin electronics and advanced quantum devices. © 2025 American Chemical Society.

关键词： Magnetization reversal

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Sn-Mediated Local Atomic Ordering Enhances Reversible Anionic Redox Activity in Cation-Disordered Li1.3Mn0.4Nb0.3O2 Cathodes

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Advanced Energy materials 2025年第0期

作者： Sun, Gang Nie, Dan Zhu, Qingjun Gao, Lijun Chang, Yi-Hung Liu, Han Yang, Jiayi Ren, Yang Shao, Yu-Cheng Ishii, Hirofumi Sui, Xulei Wang, PanPan Wang, Hsiao-Tsu Wang, Zhenbo Shenzhen Key Laboratory of Special Functional Materials Shenzhen Engineering Laboratory for Advance Technology of Ceramics Guangdong Research Center for Interfacial Engineering of Functional Materials Guangdong Provincial Key Laboratory of New Energy Materials Service Safety College of Materials Science and Engineering Shenzhen University Shenzhen518071 China Bachelor's Program in Advanced Materials Science Tamkang University No.151 Yingzhuan Rd. Tamsui Dist. New Taipei25137 Taiwan Department of Physics City University of Hong Kong 999077 Hong Kong National Synchrotron Radiation Research Center 101 Hsin-Ann Road Hsinchu Science Park Hsinchu300092 Taiwan State Key Laboratory of Space Power-Sources MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage MOE Engineering Research Center for Electrochemical Energy Storage and Carbon Neutrality in Cold Regions School of Chemistry and Chemical Engineering Harbin Institute of Technology Harbin150001 China

Recent advances in lithium-ion batteries have revealed the potential of Li-excess cation-disordered rock salt (DRX) cathodes, which expand the design space for cathode materials. The evidence of facile lattice substitution further provides a key strategy for activating redox reaction centers and enhancing the cycling performance of such materials. Here, the study explores how Sn-mediated local atomic ordering enhances reversible anionic redox activity in Li1.3Mn0.4Nb0.3O2 through the use of aberration-corrected scanning transmission electron microscopy, ex/in situ X-ray techniques, and theoretical calculation. The results demonstrate that Sn incorporation optimizes the local atomic structure, fostering the formation of rapid Li+ diffusion "elevator" pathways and short-range ordered structures, thereby enhancing the Li+ transport network. Additionally, quantitative analysis of the redox pathways and degree of participation for Mn and O during charge–discharge cycles reveals that the Sn-mediated electrode exhibits enhanced anionic O redox activity at high charging voltages, maintaining elevated activity throughout subsequent cycling. This sustained performance not only indicates increased redox capabilities but also suggests improved structural stability. By elucidating the complex interplay between composition, local structure, and performance, this study advances the understanding of DRX materials and underscores the potential of strategic elemental substitution for optimizing disordered cathode materials in next-generation energy storage systems. © 2025 Wiley-VCH GmbH.

关键词： Redox reactions

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