High temperature thermal cycling effect on the irreversible responses of lattice structure, magnetic properties and electrical conductivity in Co$_{2.75}$Fe$_{0.25}$O$_{4+δ}$ spinel oxide
R. N. Bhowmik, P. D. Babu, A. K. Sinhac, Abhay Bhisikar
We report high temperature synchrotron X-ray diffraction (SXRD), dc magnetization and current-voltage (I-V) characteristics for the samples of Co$_{2.75}$Fe$_{0.25}$O$_4$ ferrite. The material was prepared by chemical reaction of the Fe and Co nitrate solutions at pH = 11 and subsequent annealing at temperatures 200 0C, 500 0C and 900 0C. The measurements were performed by cycling the temperature from 300 K to high temperature (warming mode) and return back to 300 K (cooling mode). The SXRD patterns indicated a fine bi-phased cubic spinel structure in the highly Co rich spinel oxide. Magnetization curves showed intrinsic ferrimagnetic features and defect induced additional ferromagnetic phase at higher temperatures. Electrical conductivity showed thermal hysteresis loop between warming and cooling modes of temperature variation. The samples exhibited new information on the irreversibility phenomena of lattice structure, magnetization and electrical conductivity on cycling the measurement temperatures.
Insights on the volume variation of LiCoxMn2-xO4 electrode upon cycling: a correlative operando XRD and XAS study
Sorbonne Université, CNRS, Physicochimie des Electrolytes et Nanosystèmes interfaciaux (PHENIX)（索邦大学，法国国家科学研究中心，电解质与界面纳米系统物理化学）；Sorbonne Université, CNRS, Laboratoire de Chimie de la Matière Condensée de Paris (LCMCP)（索邦大学，法国国家科学研究中心，巴黎凝聚态物质化学实验室）；Réseau sur le Stockage Electrochimique de l’Energie (RS2E), FR CNRS 3459（电化学储能研究网络（RS2E），FR CNRS 3459）
The irreversible thermoremanent magnetization of a sole, magnetically diluted epitaxial antiferromagnetic Co$_{1-y}$O(100) layer is determined by the mean of its thermoremanent magnetizations at positive and negative remanence. During hysteresis-loop field cycling, thermoremanent magnetization exhibits successive reductions, consistent with the training effect (TE) of the exchange bias measured for the corresponding Co$_{1-y}$O(100)/Co bilayer. The TE of exchange bias is shown to have its microscopic origin in the TE of the irreversible thermoremanent magnetization of the magnetically diluted …
The rare-earth ions (RE = Eu, Dy Ho, Tm, Y) substituted charge-ordered antiferromagnetic manganites, Pr0.45RE0.05Ca0.5MnO3, were studied for the magnetic and the transport properties in the presence of external magnetic-fields of up to 14 Tesla. Regardless of the intrinsic magnetic property of RE ions, all the compounds exhibit successive step-like metamagnetic transitions at low temperatures, which are strongly correlated to their electronic transitions. At any fixed temperature in two different temperature-regimes, we observed contrary effects of the magnetic-field cycling on the resistivity…
In this work we address the interplay between two phenomena which are signatures of the out-of-equilibrium state in phase separated manganites: irreversibility against thermal cycling and aging/rejuvenation process. The sample investigated is La0.5Ca0.5MnO3, a prototypical manganite exhibiting phase separation. Two regimes for isothermal relaxation were observed according to the temperature range: for T > 100 K, aging/rejuvenation effects are observed, while for T < 100 K an irreversible aging was found. Our results show that thermal cycles act as a tool to unveil the dynamical behavior of the…
High-temperature Cu-Mn-Fe spinel-oxide nanoparticle solar selective absorber coatings are investigated experimentally and theoretically. A reliable, general approach to evaluate absorption coefficient spectra from the optical measurements of the nanoparticle-pigmented coatings is developed based on solving the inverse problem using four-flux-radiative method. The derived absorption properties of NP materials can be directly applied to predict the solar absorptance, optimize the nanoparticle-pigmented coatings, and analyze the thermal degradation, which agree well with the experimental results.…
Oxidative decomposition of organic-solvent-based liquid electrolytes at cathode material interfaces has been identified as a main reason for rapid capacity fade in high-voltage lithium ion batteries. The evolution of "cathode electrolyte interphase: (CEI) films, partly or completely consisting of electrolyte decomposition products, has also recently been demonstrated to be correlated with battery cycling behavior at high potentials. Using Density Functional Theory (DFT) calculations, the hybrid PBE0 functional, and the (001) surfaces of spinel oxides as models, we examine these two interrelate…
The rare-earth chromates (RECrO$_3$) and manganites (REMnO$_3$) where, RE = Eu, Y, Dy, Ho, Gd are constantly under scrutiny in search of room temperature magnetoelectric multiferroics. However, the artefacts and undesirable signal in some of the measurements pose a severe challenge in confirming the ferroelectric (FE) phase, especially in reference to pyroelectric current measurement technique. In this regard, we propose a simple modified approach to pyroelectric current measurement named as 4-segment thermal cycling protocol. This protocol assists in isolating the elusive, irreversible therma…
An experimental setup for determining the electrical resistivity of several types of thermoelectric materials over the temperature range 20 < T < 550 C is described in detail. One resistivity measurement during temperature cycling is also explained for Cu0.01Bi2Te2.7Se0.3 while a second measurement is made on Yb0.35Co4Sb12 as a function of time at 400 C. Both measurements confirm that the materials are thermally stable for the temperature range and time period measured. Measurements made during temperature cycling show an irreversible decrease in the electrical resistivity of Cu0.01Bi2Te2.7Se0…
Effects of High-Temperature Preconditioning on Li Plating During Low-Temperature Cycling of the COTS LG Chem HG2 Cell
German Aerospace Center（德国航空航天中心）；Helmholtz Institute Ulm for Electrochemical Energy Storage (HIU)（乌尔姆亥姆霍兹电化学能源研究所）；Jet Propulsion Laboratory—California Institute of Technology（喷气推进实验室—加州理工学院）；University of Ulm（乌尔姆大学）
本研究通过实验和三维建模，探究高温预处理对COTS LG Chem HG2电池在-20°C低温循环中锂沉积行为的影响，发现不同预处理方案导致锂沉积差异，并揭示其微观机理。
We report structural, susceptibility and specific heat studies of stoichiometric and off-stoichiometric poly- and single crystals of the A-site spinel compound FeSc2S4. In stoichiometric samples no long-range magnetic order is found down to 1.8 K. The magnetic susceptibility of these samples is field independent in the temperature range 10 - 400 K and does not show irreversible effects at low temperatures. In contrast, the magnetic susceptibility of samples with iron excess shows substantial field dependence at high temperatures and manifests a pronounced magnetic irreversibility at low temper…
Upon insertion and extraction of lithium, materials important for electrochemical energy storage can undergo changes in thermal conductivity ($Λ$) and elastic modulus ($\it M$). These changes are attributed to evolution of the intrinsic thermal carrier lifetime and interatomic bonding strength associated with structural transitions of electrode materials with varying degrees of reversibility. Using in situ time-domain thermoreflectance (TDTR) and picosecond acoustics, we systemically study $Λ$ and $\it M$ of conversion, intercalation and alloying electrode materials during cycling. The interca…
Pure ultrafine ZnFe2O4 particles have been obtained from mechanosynthesis of the ZnO and Fe2O3 oxides. The average grain diameter was estimated from x-ray diffraction to be <d> = 36(6) nm. Refinement of neutron diffraction (ND) data showed that the resulting cubic spinel structure is oxygen-deficient, with ~7% of Fe3+ ions occupying the tetrahedral A sites. Magnetization curves taken at 4.2 K showed absence of saturation up to fields H = 9 Tesla, associated to a spin-canted produced by the milling process. Field-cooled (FC) and zero-field-cooled (ZFC) curves showed irreversible behavior extend…
This paper reports on the temperature evolution of local elastic interactions between ferromagnetic CoFe films and ferroelectric BaTiO3 substrates. Polarization microscopy measurements indicate that growth-induced stripe domains in the CoFe films are preserved and strengthened during cooling and heating through the structural phase transitions of BaTiO3. Moreover, rotation of the magnetic easy axes at the tertragonal-to-orthorhombic transition (T = 278 K) and at T = 380 K simultaneously switches the local magnetization of both uniaxial domains by 90 degrees. Irreversible changes in the ferroma…
We report magnetization, resistivity and thermopower in the charge-orbital ordered antiferromagnet Nd0.75Na0.25MnO3. Magnetic-field induced collapse of antiferromagnetism is found to be accompanied by a giant negative magnetothermopower (= 80-100% for a field change of 5T) over a wide temperature (T = 60-225K) and giant magnetoresistance. While the field-induced metamagnetic transition in magnetization is reversible upon field-cycling at T > 40 K, it is irreversible at lower temperatures and this has impact on magnetoresistance, magnetothermopower as well as change in the temperature of the sa…
We investigate the exchange bias and training effects in the FM/AF heterostructures using a unified Monte Carlo dynamical approach. This real dynamical method has been proved reliable and effective in simulating dynamical magnetization of nanoscale magnetic systems. The magnetization of the uncompensated AF layer is still open after the first field cycling is finished. Our simulated results show obvious shift of hysteresis loops (exchange bias) and cycling dependence of exchange bias (training effect) when the temperature is below 45 K. The exchange bias fields decrease with decreasing the coo…
Li-O$_2$ batteries (LOB) performance degradation ultimately occurs through the accumulation of discharge products and irreversible clogging of the porous electrode during the cycling. Electrode binder degradation in the presence of reduced oxygen species can result in additional coating of the conductive surface, exacerbating capacity fading. Herein, we establish a facile method to fabricate free-standing, binder-free electrodes for LOBs in which multi-wall carbon nanotubes (MWCNT) form cross-linked networks exhibiting high porosity, conductivity, and flexibility. These electrodes demonstrate …
Enhanced EV market penetration requires durability of the battery with high energy throughput. For long-term cycle stability of silicon-graphite anode capable of high energy density, the reversible redox reactions are crucial. Here, we unveil intriguing electrochemical phenomena such as crosstalk of lithium ion ($Li^{+}$) between silicon and graphite, $Li^{+}$ accumulation in silicon, and capacity depression of graphite under high pressure, which engender the irreversible redox reactions. Active material properties, i.e. the size of silicon and the hardness of graphite, silicon-graphite anode,…
High-performance anodes for rechargeable Li-ion battery are produced by nanostructuring of the transition metal oxides on a conductive support. Here, we demonstrate a hybrid material of MnO2 directly grown onto fabrics of carbon nanotube fibres, which exhibits notable specific capacity over 1100 and 500 mAh/g at a discharge current density of 25 mA/g and 5 A/g, respectively, with coulombic efficiency of 97.5 %. Combined with 97 % capacity retention after 1500 cycles at a current density of 5 A/g, both capacity and stability are significantly above literature data. Detailed investigations invol…
The effect of polarization fatigue on the Rayleigh coefficients of ferroelectric lead zirconate titanate (PZT) thin film was systematically investigated. It was found that electrical fatigue strongly affects the Rayleigh behaviour of the PZT film. Both the reversible and irreversible Rayleigh coefficients decrease with increasing the number of switching cycles. This phenomenon is attributed to the growth of an interfacial degraded layer between the electrode and the film during electrical cycling. The methodology used in this work could serve as an alternative non-destructive way for evaluatin…
We have studied the effect of metastable, irreversibility induced by repeated thermal cycles on the electric transport and magnetization of polycrystalline samples of La1-xCaxMnO3 (0.48\leq x \leq 0.55) close to charge ordering. With time and thermal cycling (T<300 K) there is an irreversible transformation of the low-temperature phase from a partially ferromagnetic and metallic to one that is less ferromagnetic and highly resistive for the composition close to charge ordering (x=050 and 0.52). Irrespective of the actual ground state of the compound, the effect of thermal cycling is towards an…
(Mn,Fe)2(P,Si) single crystals have been successfully grown by flux method. Single crystal diffraction demonstrates that Mn0.83Fe1.17P0.72Si0.28 crystallizes in a hexagonal crystal structure (space group P-62m) at both 100 and 280 K, in the ferromagnetic and paramagnetic states, respectively. The magnetization measurements show that the crystals display a first-order ferromagnetic phase transition at their Curie temperature (TC). The preferred magnetization direction in is along the c axis. A weak magnetic anisotropy of K1 = 0.25x106 J/m3 and K2 = 0.19x106 J/m3 is found at 5 K. These values in…
Spin freezing in the $A$-site spinel FeAl$_2$O$_4$ which is a spin liquid candidate is studied using remnant magnetization and nonlinear magnetic susceptibility and isofield cooling and heating protocols. The remnant magnetization behavior of FeAl$_2$O$_4$ differs significantly from that of a canonical spin glass which is also supported by analysis of the nonlinear magnetic susceptibility term $χ_3 (T)$. Through the power-law analysis of $χ_3 (T)$, a spin-freezing temperature, $T_g$ = 11.4$\pm$0.9~K and critical exponent, $γ$ = 1.48$\pm$0.59 are obtained. Cole-Cole analysis of magnetic suscept…
The Origin of Enhanced Conductivity and Structure Change in Defective Li4Ti5O12 or Blue-LTO : a study combined theoretical and experimental perspectives
Thin films and heterostructures of hexagonal manganites as promising multiferroic materials have attracted a considerable interest recently. We report structural transformations of high quality epitaxial h-TMO/YSZ(111) films, analyzed by means of various characterization techniques. A phase transition from P63mc to P63mcm structure at TC~800 K was observed by temperature dependent Raman spectroscopy and optical ellipsometry. The latter probing directly electronic system, indicates its modification at the structural phase transition likely due to charge transfer from oxygen to Mn. In situ trans…
The influence of repeated thermal cycling on mechanical properties, structural relaxation, and evolution of the potential energy in binary glasses is investigated using molecular dynamics simulations. We consider a binary mixture with strongly non-additive cross interactions, which is annealed across the glass transition with different cooling rates and then exposed to one thousand thermal cycles at constant pressure. We found that during the first few hundred transient cycles, the potential energy minima after eachcycle gradually decrease and the structural relaxation proceeds via collective,…
