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291.
D.M. Raj Kumar N.V. Rama RaoM. Manivel Raja D.V. Sridhara RaoM. Srinivas S. Esakki MuthuS. Arumugam K.G. Suresh 《Journal of magnetism and magnetic materials》2012,324(1):26-32
Melt spun Ni50−xMn37+xIn13 (2≤x≤5) ribbons were investigated for the structure, microstructure, magneto-structural transitions and inverse magnetocaloric effect (IMCE) associated with the first-order martensitic phase transition. The influence of excess Mn in Ni site (or Ni/Mn content) on the martensite transition and the associated magnetic and magnetocaloric properties are discussed. It was found that with the increase in Mn content, the martensitic transition shifted from 325 to 240 K as x is varied from 2 to 4, and the austenite phase was stabilized at room temperature. The x=5 ribbon did not show the martensitic transition. For the x=3 ribbon, the structural and magnetic transitions are close together unlike in the x=4 ribbon in which they are far (∼60 K) apart. The zero field cooled and field cooled curves support the presence of exchange bias blocking temperature due to antiferromagnetic interactions in the ribbons. A large change in the magnetization between the martensite and austenite phases was observed for a small variation in the Ni/Mn content, which resulted in large IMCE. A large positive magnetic entropy change (ΔSM) of 32 J/kg K at room temperature (∼ 300 K) for a field change of 5 T with a net refrigeration capacity of 64 J/kg was obtained in the Ni47Mn40In13 ribbon. 相似文献
292.
Alexander Okorn Arumugam Jayaraman Lukas Englert Merle Arrowsmith Theresa Swoboda Jeanette Weigelt Carina Brunecker Merlin Hess Anna Lamprecht Carsten Lenczyk Maximilian Rang Holger Braunschweig 《Chemical science》2022,13(25):7566
The classical route to the PMe3-stabilised polycyclic aromatic hydrocarbon (PAH)-substituted diborenes B2Ar2(PMe3)2 (Ar = 9-phenanthryl 7-Phen; Ar = 1-pyrenyl 7-Pyr) via the corresponding 1,2-diaryl-1,2-dimethoxydiborane(4) precursors, B2Ar2(OMe)2, is marred by the systematic decomposition of the latter to BAr(OMe)2 during reaction workup. Calculations suggest this results from the absence of a second ortho-substituent on the boron-bound aryl rings, which enables their free rotation and exposes the B–B bond to nucleophilic attack. 7-Phen and 7-Pyr are obtained by the reduction of the corresponding 1,2-diaryl-1,2-dichlorodiborane precursors, B2Ar2Cl2(PMe3)2, obtained from the SMe2 adducts, which are synthesised by direct NMe2–Cl exchange at B2Ar2(NMe2)2 with (Me2S)BCl3. The low-lying π* molecular orbitals (MOs) located on the PAH substituents of 7-Phen and 7-Pyr intercalate between the B–B-based π and π* MOs, leading to a relatively small HOMO–LUMO gap of 3.20 and 2.72 eV, respectively. Under vacuum or at high temperature 7-Phen and 7-Pyr undergo intramolecular hydroarylation of the B B bond to yield 1,2-dihydronaphtho[1,8-cd][1,2]diborole derivatives. Hydrogenation of 7-Phen, 7-Pyr and their 9-anthryl and mesityl analogues III and II, respectively, results in all cases in splitting of the B–B bond and isolation of the monoboranes (Me3P)BArH2. NMR-spectroscopic monitoring of the reactions, solid-state structures of isolated reaction intermediates and computational mechanistic analyses show that the hydrogenation of the three PAH-substituted diborenes proceeds via a different pathway to that of the dimesityldiborene. Rather than occurring exclusively at the B–B bond, hydrogenation of 7-Ar and III proceeds via a hydroarylated intermediate, which undergoes one B–B bond-centered H2 addition, followed by hydrogenation of the endocyclic B–C bond resulting from hydroarylation, making the latter effectively reversible.In contrast to classical B–B bond-centred diborene hydrogenation, polycyclic aromatic hydrocarbon-substituted diborenes first undergo thermal intramolecular hydroarylation, followed by hydrogenation of the remaining B–B and endocyclic B–C bonds. 相似文献
293.
Dr. Zehao Cui Zezhou Guo Prof. Arumugam Manthiram 《Angewandte Chemie (International ed. in English)》2023,62(50):e202313437
While it is widely recognized that the operating temperature significantly affects the energy density and cycle life of lithium-ion batteries, the consequence of electrode-electrolyte interphase chemistry to sudden environmental temperature changes remains inadequately understood. Here, we systematically investigate the effects of a temperature pulse (T pulse) on the electrochemical performance of LiNi0.8Mn0.1Co0.1O2 (NMC811) pouch full cells. By utilizing advanced characterization tools, such as time-of-flight secondary-ion mass spectrometry, we reveal that the T pulse can lead to an irreversible degradation of cathode-electrolyte interphase chemistry and architecture. Despite negligible immediate impacts on the solid-electrolyte interphase (SEI) on graphite anode, aggregated cathode-to-anode chemical crossover gradually degrades the SEI by catalyzing electrolyte reduction decomposition and inducing metallic dead Li formation because of insufficient cathode passivation after the T pulse. Consequently, pouch cells subjected to the T pulse show an inferior cycle stability to those free of the T pulse. This work unveils the effects of sudden temperature changes on the interphase chemistry and cell performance, emphasizing the importance of a proper temperature management in assessing performance. 相似文献
294.
Dr. Jiarui He Dr. Amruth Bhargav Hyunki Sul Prof. Arumugam Manthiram 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(3):e202216267
Lithium-organosulfur (Li-OS) batteries, despite possessing high theoretical specific capacity, encounter a few practical challenges, including unsatisfactory lifespan and low active material utilization under realistic conditions. Here, diisoropyl xanthogen polysulfide (DIXPS) has been selected as a model organosulfur compound to investigate the practical feasibility of Li-OS batteries under realistic conditions. A well-designed freestanding carbon sponge decorated with Fe3N nanoparticles (C@Fe3N) is introduced into the Li-OS cells as a scaffold for both Li and DIXPS. The lithiophilic property of the C@Fe3N host guides uniform lithium deposition at the anode, and the catalysis of the DIXPS conversion reaction promotes the kinetics at the cathode. Impressively, the synergistic effect of C@Fe3N leads to an extremely stable cycling performance over 1 000 cycles in a Li-OS full cell under realistic conditions. 相似文献
295.
The reactions of P(MeNCH2CH2)3N, 1, with Mel, EtI, EtBr, n-PrBr, n-BuI, i-PrBr, PhCH2CHBrCH3, MeCHBr(CH2)4Me, s-BuBr, and t-BuBr were studied. The reactions of the primary alkyl halides produced the corresponding phosphonium cationic compounds, whereas the secondary and tertiary halides underwent elimination to form the corresponding olefins and the protonated form of 1. Based on 1H and 13C NMR studies, it appears that elimination is exclusively trans, favoring the Saytzeff product. It was also observed that this reaction is enhanced by the solvent CH3CN. The X-ray crystal structure of [Me(I)] I is also reported, featuring a transannular distance of 2.773 Å (2) facilitated by a rather wide average equatorial MeN-P-NMe bond angle of 113.1 (2)°. © 1996 John Wiley & Sons, Inc. 相似文献
296.
Sitaram Ramakrishnan Shidaling Matteppanavar Andreas Schönleber Bikash Patra Birender Singh Arumugam Thamizhavel Bahadur Singh Srinivasan Ramakrishnan Sander van Smaalen 《Annalen der Physik》2023,535(6):2200611
Temperature-dependent electronic and magnetic properties are reported for nickel-deficient NiV2Se4. Single-crystal X-ray diffraction shows it to crystallize in the monoclinic Cr3S4 structure type with space group and vacancies on the Ni site, resulting in the composition Ni0.85V2Se4 in agreement with our electron-probe microanalysis. Structural distortions are not observed down to 1.5 K. Nevertheless, the electrical resistivity shows metallic behavior with a broad anomaly around 150–200 K that is also observed in the heat capacity data. This anomaly indicates a change of state of the material below 150 K. It is believed that this anomaly could be due to spin fluctuations or charge-density-wave fluctuations, where the lack of long-range order is caused by vacancies at the Ni site of Ni0.85V2Se4. The non-linear temperature dependence of the resistivity as well as an enhanced value of the Sommerfeld coefficient mJ mol−1 K−2 suggest strong electron–electron correlations in this material. First-principles calculations performed for NiV2Se4, which are also applicable to Ni0.85V2Se4, classify this material as a topological metal with and coexisting electron and hole pockets at the Fermi level. The phonon spectrum lacks any soft phonon mode, consistent with the absence of periodic lattice distortion in the present experiments. 相似文献
297.
Vellapandi Saravanan Veera Sena Hariharan Arumugam Khajanajimudeen Mohamed Mydeen Balaji Krishnasamy Mohamedmustafa Mohamed Iqbal Alagar Muthukaruppan 《先进技术聚合物》2023,34(2):568-577
An attempt has been made to develop hybrid composites from benzoxazine monomer (C-ddm) hybridized with DGEBA epoxy resin (EP) and reinforced with varying weight percentages (20 wt%, 40 wt%, 60 wt%, 80 wt% and 100 wt%) of glycidoxypropyltrimethoxy- silane (GPTMS) functionalized granite dust (GD) obtained from industrial granite cutting and polishing process in order to utilize them for electrical insulation applications. The thermal stability of granite dust reinforced poly(EP-co-C-ddm) composites was studied by TGA analysis. Among the composites samples studied, 100 wt% GD reinforced poly(EP-co-C-ddm) composites possess better thermal stability than that of other neat matrices and composites. Among the composites prepared using varying weight percentages of functionalized GD reinforcement, it was observed that 80 wt% GD reinforced poly(EP-co-C-ddm) composites possesses better hydrophobic character than that of other neat matrices and composites. The value of LOI calculated for neat matrix (poly[EP-co-C-ddm]) and 20 wt%, 40 wt%, 60 wt%, 80 wt% and 100 wt% GD reinforced composites was found to be 22, 28, 34, 40, 43 and 45 respectively. The 80 wt% GD reinforced poly(EP-co-C-ddm) composites possess the higher values of tensile strength and flexural strength of 47 MPa and 140 MPa, respectively than those of their samples. The values of electrical surface resistivity and electrical volume resistivity of all the neat matrices and GD reinforced polybenzoxazine composites were found to be in the order of 1012 and 1013 respectively. The values of dielectric strength obtained from break down voltage (BDV) for neat matrix [poly(EP-co-C-ddm)] and 20 wt%, 40 wt%, 60 wt%, 80 wt% and 100 wt% of GD reinforced poly(EP-co-C-ddm) composites are 15.0, 15.5, 16.5, 17.0, 17.0 and 17.0 kV/mm, respectively. Data obtained from thermal stability, hydrophobic behavior and dielectric studies it was inferred that the hybrid polymer composites developed in the present work can be conveniently used in the form insulators, sealants, adhesives and matrices where application demands at high-performance industrial and engineering applications. 相似文献
298.
Rajasekaran Sruthi Reghunath B. Shalini K. R. Sunaja Devi Saravanakumar B. Johnson William J. Pinheiro Dephan Arumugam Madan Kumar 《Journal of Solid State Electrochemistry》2023,27(4):911-925
Journal of Solid State Electrochemistry - In the recent years, the whole world is looking for better energy storage devices. Supercapacitors are among the most promising high-capacity... 相似文献
299.
Sunil Kumar Selvakumar Arumugam Dr. Björn Schwarz Prof. Dr. Helmut Ehrenberg Prof. Dr. Kartik Chandra Mondal 《欧洲无机化学杂志》2023,26(10):e202200774
A representative Co(II) based single ion magnet (SIM) with N2O2 donor set and distorted pseudo-tetrahedral geometry has been synthesized and characterized to study the atomic and electronic structure. DC magnetometry results have been evaluated by means of a phenomenological Hamiltonian approach regarding zero field splitting (ZFS) parameters and compared with results from ab-initio multi-reference CASSCF (complete active space self-consistent field) calculations and qualitative ligand field theory (AILFT). Profound investigation of spin-lattice relaxation with the variation of temperature (from 1.8 to about 8 K) and magnetic field (at 14 different fields from zero up to 1 T) have been performed based on AC magnetometry. Under an applied dc magnetic field, spin-lattice relaxation occurs via a direct process with T2 temperature dependence due to limited heat transfer at very low temperature and above 5 K relaxation by an Orbach process with an energy barrier of ≈80 K dominates. 相似文献