Browsing by Author "Barpanda, P"

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    Complex magnetism of quasi-1D maricite-type NaFePO4
    (AOCNS 2015, 2015-07-23) Avdeev, M; Piltz, RO; Ling, CD; Auckett, JE; Barpanda, P; Cadogan, JM
    We recently reported the magnetic structure of maricite-type NaFePO4 determined using neutron powder diffraction data collected at 3 K1. The crystal structure of this compound is derived from the olivine (Mg2SiO4) type by an ordered distribution of Na and Fe over the two inequivalent Mg sites in the olivine cell. This leads to a magnetically quasi-1D arrangement in which edge-sharing (FeO6) chains are connected to each other only via phosphate groups with a shortest interchain Fe-Fe distance of ~5 Å vs. intrachain distance of ~3.4 Å. Here we report the results of further studies using magnetometry, heat capacity, Mossbauer, and variable field and temperature powder and single crystal neutron diffraction measurements, which reveal not only an intermediate incommensurate magnetic phase existing in zero field within a very narrow interval of ~2 K, but also a metamagnetic transition around 5 T (at 2 K). We will also present and discuss the evolution of the magnetic structure of NaFePO4 as a function of temperature and magnetic field in connection with the crystal structure and compared to that of other maricite type compositions such as AgMnVO42.
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    Inside Back Cover: t-Na2(VO)P2O7: A 3.8 V pyrophosphate insertion material for sodium-ion batteries
    (Wiley, 2014-06-23) Barpanda, P; Liu, G; Avdeev, M; Yamada, A
    Pyrophosphate oxyanionic framework compounds offer a great platform to investigate new battery materials. In our continuing effort to explore pyrophosphate cathodes for sodium-ion batteries, we report, for the first time, the synthesis and use of tetragonal Na2(VO)P2O7 as a potential sodium-ion insertion material. This material can be easily prepared by using a conventional solid-state route at a relatively low temperature of 400 °C. Stabilizing as a tetragonal structure with an open framework, the material offers pathways for Na+ diffusion. The as-synthesized material, with no further cathode optimization, yields a reversible capacity (Q) approaching 80 mAh g−1 (QTheoretical=93.4 mAh g−1) involving a one electron V5+/V4+ redox potential located at 3.8 V (vs. Na/Na+). Furthermore, the material exhibits decent rate kinetics and reversibility. Combining green synthesis and moderate electrochemical properties, t-Na2(VO)P2O7 is reported as a new addition to the growing family of pyrophosphate cathodes for sodium-ion batteries.© 2014, WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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    Magnetic structure and properties of centrosymmetric twisted-melilite K2CoP2O7
    (Royal Society of Chemistry, 2017-04-24) Sale, M; Avdeev, M; Mohamed, Z; Ling, CD; Barpanda, P
    Twisted-melilite dipotassium cobalt pyrophosphate (K2CoP2O7, P42/mnm, #136), originally reported by Gabelica-Robert (1981), was synthesized in powder form by a standard solid-state reaction route. The magnetic properties of the material were studied by magnetometry and its magnetic structure determined using neutron powder diffraction for the first time. Below TN = 11 K, the material adopts a G-type antiferromagnetic structure with moments aligned in the ab-plane (magnetic space group Pn′nm, #58.3.473). Ab initio calculations were performed to examine the isotropic magnetic spin exchange parameters as well as the preferred direction of magnetic moments due to spin–orbit coupling. The relationship between crystal structure geometry and the strength of the magnetic interactions was examined and compared to those of melilite-type Sr2CoGe2O7. © The Royal Society of Chemistry 2017
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    Magnetic structure and properties of NaFePO4 polymorphs: antiferromagnetic ordering and spin-flop transition
    (IOP Publishing, 2014-10-09) Barpanda, P; Avdeev, M; Ling, CD
    In recent years, the cost and sustainability concerns have renewed research efforts on sodium-ion batteries, propelling investigation on various layered oxides and polyanionic family of insertion compounds for low-cost and large-scale cathode applications. These cathode insertion compounds are functional materials, involving redox active 3d transition metals (e.g. Fe/Co/Ni) that are often magnetic in nature. During the Na (de)insertion process involving redox reaction of transition metals and structural alteration, the magnetic magnetic structure/ properties can vary significantly. We have investigated the magnetic structure and properties of NaFePO4 polyanionic system, which exists in two distinct polymorphs: metastable triphylite and stable maricite. The details of these structures are shown in the figure. Both these polymoprhs undergo antiferromagnetic ordering below 50 K (for triphylite) and 13 K (for maricite). Using the magnetic susceptibility, heat capacity and low temperature neutron powder diffraction, the magnetic structure of these two distinct polymorphs have been solved. The details of these antiferromagnetic structures will be described considering the super- and super-superexchange interactions. In addition, investigating the maricite NaFePO4 polymorph, which consists of edge-sharing FeO6 octahedral chains, we have discovered the occurrence of spin-flop transition below 40 kOe using susceptibility measurement and low-temperature Mossbauer spectroscopy. This spin-flopping (or metamagnetism) phenomenon in maricite NaFePO4 will be described in detail [1-5] to showcase the rich magnetism present in NaFePO4 insertion materials. © 2014 ECS - The Electrochemical Society
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    Magnetic structure and properties of the Na2CoP2O7 pyrophosphate cathode for sodium-ion batteries: a supersuperexchange-driven non-collinear antiferromagnet
    (American Chemical Society, 2012-12-17) Barpanda, P; Avdeev, M; Ling, CD; Lu, J; Yamada, A
    The crystal and magnetic structure and properties of the Na2CoP2O7 Na+-ion battery cathode material have been characterized by magnetic susceptibility, specific heat, and variable-temperature neutron powder diffraction measurements. Na2CoP2O7 crystallizes in the orthorhombic space group Pna21 with a = 15.4061(3) Å, b = 10.28854(9) Å, and c = 7.70316(15) Å, having a layered structure with slabs of [CoP2O7]∞ separated by Na cations. The magnetic property measurements and neutron diffraction data analysis reveal that the material undergoes long-range ordering to a noncollinear antiferromagnetic G-type structure below TN ≈ 6.5 K. The magnetic structure is rationalized as a result of supersuperexchange between Co2+ atoms linked by phosphate groups.© 2013, American Chemical Society.
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    Magnetic structure and properties of the rechargeable battery insertion compound Na2FePO4F
    (American Chemical Society, 2013-12-26) Avdeev, M; Ling, CD; Tan, TT; Li, S; Oyama, G; Yamada, A; Barpanda, P
    The magnetic structure and properties of sodium iron fluorophosphate Na2FePO4F (space group Pbcn), a cathode material for rechargeable batteries, were studied using magnetometry and neutron powder diffraction. The material, which can be described as a quasi-layered structure with zigzag Fe-octahedral chains, develops a long-range antiferromagnetic order below ∼3.4 K. The magnetic structure is rationalized as a super-exchange-driven ferromagnetic ordering of chains running along the a-axis, coupled antiferromagnetically by super-super-exchange via phosphate groups along the c-axis, with ordering along the b-axis likely due to the contribution of dipole–dipole interactions. © 2013 American Chemical Society
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    Magnetic structure of fluorophosphate Na2MnPO4F sodium battery material
    (Elsevier, 2022-04) Lochab, S; Rayaprol, S; Avdeev, M; Sharma, L; Barpanda, P
    The rapid usage and consequent depletion of lithium-based resources necessary for rechargeable Li-ion batteries (LIBs) have triggered research on alternate battery chemistries [[1], [2], [3]]. Here, Na-ion batteries (SIBs) form a suitable candidate powered by abundance and economy of sodium-based resources [2]. SIBs have striking operational similarity to LIBs and can cater to suites of mobile and stationary energy storage systems, particularly if the application is independent of gravimetric/volumetric energy density. In the quest to realize robust SIBs, variety of oxides and polyanionic insertion materials have been explored as potential cathodes. Polyanionic compounds, in particular, can provide tuneable redox potential and stable frameworks [3]. Fluorophosphates, with general formulae Na2MPO4F (M ​= ​Mn, Fe, Co, Ni), form one such example with potential two Na+ (de)insertion [4,5]. The presence of highly electronegative F− species imparts higher ionicity and consequently higher redox potential. In this mixed-polyanionic family, deviating from the orthorhombic structure (s.g. Pbcn, #60) of fluorophosphates (M ​= ​Fe, Co, Ni), the Mn analogue Na2MnPO4F assumes a monoclinic framework (s.g. P21/n, #14). Over the last decade, fluorophosphates have been widely investigated focusing on their crystal structure and electrochemical properties. Nonetheless, there is room to probe their magnetic properties as these fluorophosphates can exhibit interesting magnetic properties stemming from unpaired electrons in the 3d metal orbitals. Also, various arrangements of the MO4F2 octahedra and PO4 tetrahedra in fluorophosphate end-members can lead to different types of magnetic interactions (super-super-exchange, super-exchange etc.). Generally, in polyanionic materials having different polyhedra building blocks, magnetic interactions are possible via the M-O-O-M pathways. These interactions can lead to antiferromagnetic ordering or more-complex magnetic structures if there is presence of frustration. Magnetic structure and properties of the orthorhombic end-members (e.g. Na2FePO4F) have been earlier reported showing long-range antiferromagnetic ordering below a transition temperature of 3.4 ​K [6]. Unlike the orthorhombic polymorphs (M ​= ​Fe Co, Ni) with face-sharing polyhedral building blocks, the monoclinic Na2MnPO4F involves only corner-sharing among constituent polyhedra. This structural deviation leads to unique magnetic spin arrangement in Na2MnPO4F fluorophosphate, which has been elucidated synergising magnetometry and neutron powder diffraction tools. © 2022 Elsevier Inc.
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    Magnetic structure of melilite-related centrosymmetric K_2CoP_2O_7: neutron diffraction and DFT study
    (Asia-Oceania Neutron Scattering Association, 2015-07-23) Sale, M; Avdeev, M; Ling, CD; Barpanda, P
    A great number of X_2(ZT_2)O_7 compositions with large X=Ln, Ca-Ba, Na, K and small Z and T=Be,Al,Si,Ga,Ge,P,V adopt the melilite crystal structure type. The structure is built of tetrahedral layers of five-member rings and X is located in the interlayer space. Typically, the materials crystallize in the non-centrosymmetric P-42_1m space group. The compositions with magnetic ions (e.g. Z=Mn"2"+,Fe"2"+,Co"2"+,Cu"2"+) are very interesting systems from the magnetic structure point of view due to the 2D character of the structure and lack of inversion center. Depending on chemistry and geometry of a particular composition, a variety of magnetic structures were reported, from simple 3D antiferromagnets to 2D spirals and multiferroics. During our investigations of melilite-type materials a K_2CoP_2O_7 composition was prepared and its magnetic property and structure characterized. The material is built of melilite-type tetrahedral layers but crystallizes in centro-symmetric P4/mnm space group. The magnetic structure has been determined using neutron powder diffraction on the Echidna diffractometer (ANSTO) and further explored with DFT. The results will be presented and discussed in the context of the broad melilite structural family.
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    Magnetic structure of some battery materials and why it matters
    (International Battery Materials Association, 2014-03-02) Avdeev, M; Ling, CD; Mohamed, Z; Barpanda, P; Yamada, A; Ben Yahia, H; Shikano, M
    Operation of batteries with insertion cathodes is typically based on a redox reaction Mn+/Mn+p (p=1,2) of transition metals. The motivation to increase gravimetric energy density and reduce cost naturally drives research to the light, i.e. 3d, transition metals M=V-Ni, which in turn are also paramagnetic ions and may order magnetically. Using neutron diffraction and magnetometry we explored magnetic structure and properties of some materials recently synthesized in search of better cathode materials: Na2CoP2O7, maricite- and triphylite-NaFePO4, Na2FePO4F, M(OH)xF2-x (M=Co,Fe), Li2MnSiO4, Li2CoSiO4, LiNaCoPO4F, LiNaFePO4F. The detailed magnetic structures will be presented and features of crystal structures affecting the type of magnetic ordering will be discussed. Although polyanionic materials (phosphates and silicates) are magnetically low density systems and thus order at low temperature (< 50 K), the information on magnetic structure is important for accurate DFT calculations. The effect of neglecting magnetic order on the DFT based quantitative predictions will be illustrated.
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    Magnetic structures of NaFePO4 maricite and triphylite polymorphs for sodium-ion batteries
    (American Chemical Society, 2013-08-05) Avdeev, M; Mohamed, Z; Ling, CD; Lu, J; Tamaru, M; Yamada, A; Barpanda, P
    The magnetic structure and properties of polycrystalline NaFePO4 polymorphs, maricite and triphylite, both derived from the olivine structure type, have been investigated using magnetic susceptibility, heat capacity, and low-temperature neutron powder diffraction. These NaFePO4 polymorphs assume orthorhombic frameworks (space group No. 62, Pnma), built from FeO6 octahedral and PO4 tetrahedral units having corner-sharing and edge-sharing arrangements. Both polymorphs demonstrate antiferromagnetic ordering below 13 K for maricite and 50 K for triphylite. The magnetic structure and properties are discussed considering super- and supersuperexchange interactions in comparison to those of triphylite-LiFePO4. © 2013, American Chemical Society
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    Marinite Li2Ni(SO4)2 as a new member of the bisulfate family of high-voltage lithium battery cathodes
    (American Chemical Society, 2021-07-31) Singh, S; Jha, PK; Avdeev, M; Zhang, WL; Jayanthi, K; Navrotsky, A; Alshareef, HM; Barpanda, P
    Development of sustainable, economic, and high-voltage cathode materials forms the cornerstone of cathode design for Li-ion batteries. Sulfate chemistry offers a fertile ground to discover high-voltage cathode materials stemming from a high electronegativity-based inductive effect. Herein, we have discovered a new polymorph of high-voltage m-Li2NiII(SO4)2 bisulfate using a scalable spray drying route. Neutron and synchrotron diffraction analysis revealed a monoclinic structure (s.g. P21/c, #14) built from corner-shared NiO6 octahedra and SO4 tetrahedra locating all Li+ in a distinct site. Low-temperature magnetic susceptibility and neutron diffraction measurements confirmed long-range A-type antiferromagnetic ordering in m-Li2NiII(SO4)2 below 15.2 K following the Goodenough–Kanamori–Anderson rule. In situ X-ray powder diffraction displayed an irreversible (monoclinic → orthorhombic) phase transformation at ∼400 °C. The m-Li2NiII(SO4)2 framework offers two-dimensional Li+ migration pathways as revealed by the bond valence site energy (BVSE) approach. The electronic structure obtained using first-principles (DFT) calculation shows a large electronic band gap (Eg ∼ 3.8 eV) with a trapped state near the Fermi energy level triggering polaronic conductivity. As per the DFT study, m-Li2NiII(SO4)2 can work as a 5.5 V (vs Li+/Li0) cathode for Li-ion batteries, with suitable electrolytes, coupling both cationic (NiII/III) and anionic (O–) redox activity. © 2021 American Chemical Society
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    Na2FeP2O7: a safe cathode for rechargeable sodium-ion batteries
    (American Chemical Society, 2013-09-10) Barpanda, P; Liu, G; Ling, CD; Tamaru, M; Avdeev, M; Chung, SC; Yamada, Y; Yamada, A
    Vying for newer sodium-ion chemistry for rechargeable batteries, Na2FeP2O7 pyrophosphate has been recently unveiled as a 3 V high-rate cathode. In addition to its low cost and promising electrochemical performance, here we demonstrate Na2FeP2O7 as a safe cathode with high thermal stability. Chemical/electrochemical desodiation of this insertion compound has led to the discovery of a new polymorph of NaFeP2O7. High-temperature analyses of the desodiated state NaFeP2O7 show an irreversible phase transition from triclinic (P (1) over bar) to the ground state monoclinic (P2(1)/c) polymorph above 560 degrees C. It demonstrates high thermal stability, with no thermal decomposition and/or oxygen evolution until 600 degrees C, the upper limit of the present investigation. This high operational stability is rooted in the stable pyrophosphate (P2O7)(4-) anion, which offers better safety than other phosphate-based cathodes. It establishes Na2FeP2O7 as a safe cathode candidate for large-scale economic sodium-ion battery applications. © 2013, American Chemical Society.
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    Neutron diffraction study of the li-ion battery cathode Li2FeP2O7
    (American Chemical Society, 2013-03-18) Barpanda, P; Rousse, G; Ye, T; Ling, CD; Mohamed, Z; Klein, Y; Yamada, A
    With a combination of magnetic susceptibility measurements and low-temperature neutron diffraction analyses, the magnetic structure of Li2FeP2O7 cathode has been solved. This pyrophosphate Li2FeP2O7 compound stabilizes into a monoclinic framework (space group P2(1)/c),having a pseudolayered structure with the constituent Li/Fe sites distributed into MO6 and MO5 building units. The magnetic susceptibility follows a Curie Weiss behavior above 50 K. Li2FeP2O7 shows a long-range antiferromagnetic ordering at T-N = 9 K, as characterized by the appearance of distinct additional peaks in the neutron diffraction pattern below TN. Its magnetic reflections can be indexed with a propagation vector k = (0,0,0). The magnetic moments inside the FeO6-FeO5 clusters are ferromagnetic, whereas these clusters are antiferromagnetic along the chains. The adjacent chains are in turn ferromagnetically arranged along the a-axis. The magnetic structure of Li2FeP2O7 cathode material is described focusing on their localized spin spin exchange. The magnetic structure and properties have been generalized for Li2FeP2O7 Li2CoP2O7 binary solid solutions. © 2013, American Chemical Society.
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    A new polymorph of Na2MnP2O7 as a 3.6 V cathode material for sodium-ion batteries
    (Royal Society of Chemistry, 2013-01-01) Barpanda, P; Ye, T; Avdeev, M; Chung, SC; Yamada, A
    Exploring novel low-cost cathodes for sodium-ion batteries, here we unveil [small beta]-Na2MnP2O7, a new pyrophosphate cathode. Stabilizing into a triclinic structure, it was found to be electrochemically active, delivering a discharge capacity approaching 80 mA h g-1 along with the highest ever Mn3+/Mn2+ redox potential located at 3.6 V. © 2013, Royal Society of Chemistry
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    Polymorphism and temperature-induced phase transitions of Na2CoP2O7
    (American Chemical Society, 2019-12-04) Avdeev, M; Wang, CW; Barpanda, P; Fujii, K; Yashima, M
    Polymorphism and temperature-induced phase transitions of Na2CoP2O7 were studied by in situ neutron powder diffraction and complemented by ab initio calculations to reconcile previous reports of its three polymorphs. We show that the “blue” form prepared at 873 K exists at room temperature in the orthorhombic Pna21 (= P21cn) phase, which transforms via a first-order transition to the tetragonal form at the temperature close to room temperature (∼335 K). Just above the transition, the tetragonal form is likely incommensurately modulated with the modulation vanishing at ∼423 K. Above that temperature the phase remains in the unmodulated tetragonal state (P42/mnm) until melting at ∼900 K. Upon cooling after melting, Na2CoP2O7 crystallizes into the “rose” triclinic P1 form which persists while it cools to room temperature, apparently stabilized by the barrier of the reconstructive “rose”–“blue” transition. We also discuss the relationship between the tetragonal and orthorhombic structures, the driving forces of the orthorhombic distortion, and similarity to Na2ZnP2O7 and the melilite-type structural family. © 2019 American Chemical Society
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    Revisiting the layered Na3Fe3 (PO4) 4 phosphate sodium insertion compound: structure, magnetic and electrochemical study
    (IOP Publishing, 2019-11-18) Shinde, GS; Gond, R; Avdeev, M; Ling, CD; Rao, RP; Adams, S; Barpanda, P
    Layered sodium iron phosphate phase [Na3Fe3(PO4)4] was synthesized by solution combustion synthesis method, marking the first attempt of solvothermal synthesis of this phase. Its crystal structure was verified by synchrotron and neutron powder diffraction. Rietveld analyses proved the phase purity and formation of monoclinic framework with C2/c symmetry. It undergoes an antiferromagnetic ordering ~27 K. This combustion prepared nanoscale Na3Fe3(PO4)4 compound was found to be electrochemically active with a stepwise voltage profile involving an Fe3+/Fe2+ redox activity centred at 2.43 V vs. Na/Na+. Despite various cathode optimization, only 1.8 Na+ per formula unit could be reversibly inserted into the Na3Fe3(PO4)4 framework leading to capacity close to 50 mAh g−1. This limited electrochemical activity can be rooted to (i) relatively large diffusion barrier (ca. 0.28 eV) as per Bond valence site energy (BVSE) calculations and (ii) possible structural instability during (de)sodiation reaction. © 2019 The Author(s). CC-BY licence - Published by IOP Publishing Ltd
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    Role of fuel on cation disorder in magnesium aluminate (MgAl2O4) spinel prepared by combustion synthesis
    (American Ceramic Society, 2015-06-19) Dwibedi, D; Avdeev, M; Barpanda, P
    Magnesium aluminate spinel (MgAl2O4) forms an interesting system having tetrahedral and octahedral voids filled with near similar sized divalent Mg2+ and trivalent Al3+ cations. Structural disorder (e.g., Mg–Al antisite defects) can be tuned by synthetic conditions. This study reports the evolution of Mg/Al disorder in MgAl2O4 prepared by combustion synthesis using different types of fuels. The effect of nature of fuel and the final calcination temperature (600°C–900°C for 9 h) on degree of cation ordering has been investigated combining powder X‐ray (XRD) and neutron (NPD) diffraction. The results indicate very high degree of inversion in the samples crystallized at low annealing temperature, which on further annealing reduces toward the thermodynamically stable values. Raman spectroscopy, probing MgO4, and AlO4 tetrahedral bonds, confirmed the results at a local level. © 2015 The American Ceramic Society
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    t-Na2(VO)P2O7: A 3.8 V Pyrophosphate insertion material for sodium-ion batteries (ChemElectroChem 9/2014)
    (Wiley, 2014-09-04) Barpanda, P; Liu, G; Avdeev, M; Yamada, A
    The picture shows a bond valence sum map of a fresnoite Na2(VO)P2O7 cathode that acts as a novel 3.8 V insertion host material for sodium-ion batteries. This work is presented on p. 1488 by P. Barpanda, A. Yamada et al. © 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim