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Synchrotron radiation based techniques are powerful tools for battery research and allow probing a wide range of length scales, with different depth sensitivities and spatial/temporal resolutions. Operando experiments enable characterization during functioning of the cell and are thus a precious tool to elucidate the reaction mechanisms taking place. In this perspective, the current state of the art for the most relevant techniques (scattering, spectroscopy, and imaging) is discussed together with the bottlenecks to address, either specific for application in the battery field or more generic. The former includes the improvement of cell designs, multi-modal characterization and development of protocols for automated or at least semi-automated data analysis to quickly process the huge amount of data resulting from operando experiments. Given the recent evolution in these areas, accelerated progress is expected in the years to come, which should in turn foster battery performance improvements., The authors are grateful for funding through PTI+ TRANS-ENER+: “Alta Tecnología clave en la transición en el ciclo energético”, part of the CSIC program for the Spanish Recovery, Transformation and Resilience Plan funded by the Recovery and Resilience Facility of the European Union, established by the Regulation (EU) 2020/2094. ICMAB-CSIC members thank the Spanish Agencia Estatal de Investigación Severo Ochoa Programme for Centres of Excellence in R&D (CEX2019-000917-S)., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

Spin to charge conversion process in a broad range of temperatures is studied in La0.92MnO3/Pt bilayers prepared by polymer-assisted deposition (PAD). It is shown that an excellent LMO/Pt interface can be obtained in spite of using ex situ deposition of the Pt layer. The values obtained for the effective spin-mixing conductance, g↑↓eff = 0.76 × 1015 cm−2, suggest that significant spin transport across the LMO/Pt interface could be achieved. Spin pumping experiments generate a transversal voltage signal VISHE, due to spin to charge conversion via inverse spin Hall effect, that has been detected down to about 100 K with values of the spin-Hall angle, θSH, of about 2.5%, slightly decreasing on reducing temperature in the analyzed temperature range. These results indicate that LMO is a promising perovskite building block for all-oxide multifunctional high-frequency spintronics devices and that PAD technique provides oxide epitaxial thin films of good quality adequate for spintronic applications., We acknowledge financial support from the Spanish Ministry of Science, Innovation and Universities through Severo Ochoa (CEX2019-000917-S), and SPINCURIOX (RTI2018-099960-BI00) and AMONANO (PID2020-112914RB-I00) projects co-financed by the European Regional Development Funds. AMONANO also received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement no. 823717-ESTEEM3. Hailin Wang acknowledges financial support from the China Scholarship Council (CSC)., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

2D materials offer the ability to expose their electronic structure to manipulations by a proximity effect. This could be harnessed to craft properties of 2D interfaces and van der Waals heterostructures in devices and quantum materials. We explore the possibility to create an artificial spin polarized electrode from graphene through proximity interaction with a ferromagnetic insulator to be used in a magnetic tunnel junction (MTJ). Ferromagnetic insulator/graphene artificial electrodes were fabricated and integrated in MTJs based on spin analyzers. Evidence of the emergence of spin polarization in proximitized graphene layers was observed through the occurrence of tunnel magnetoresistance. We deduced a spin dependent splitting of graphene's Dirac band structure (∼15 meV) induced by the proximity effect, potentially leading to full spin polarization and opening the way to gating. The extracted spin signals illustrate the potential of 2D quantum materials based on proximity effects to craft spintronics functionalities, from vertical MTJs memory cells to logic circuits., This work has received funding from the European Union’s H2020 Future and Emerging Technologies “Graphene Flagship” (Grant Core3 No. 881603), “SINFONIA” (No. 881603) projects and a Grant Agreement Marie Skłodowska Curie “ITN Spinograph” (No. 697904), as well as from EPSRC (EP/P005152/1, EP/K016636/1). This research is supported by a public grant overseen by the French National Research Agency (ANR) as part of the “Investissements d’Avenir” program Labex NanoSaclay (ANR-10-LABX-0035), as well as grants STEM2D (ANR-19-CE24-0015), MIXES (ANR-19-CE09-0028), and by the Flag-ERA JTC 2019 project “SOGraphMEM” (ANR-19-GRFI-0001-07). This work has also received fundings from the “Spanish ministry of Science and Innovation” through “Severo Ochoa” (CEX2019-000917-S) and “OXISOT” (PID2021-128410OB-I00)., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

In this work, we report a systematic study of the influence of film thickness on the structural and magnetic properties of epitaxial thin films of Pr2-δNi1-xMn1+xO6-y (PNMO) double perovskite grown on top of two different (001)-SrTiO3 and (001)-LaAlO3 substrates by RF magnetron sputtering. A strong dependence of the structural and magnetic properties on the film thickness is found. The ferromagnetic transition temperature (TC) and saturation magnetization (Ms) are found to decrease when reducing the film thickness. In our case, the thinnest films show a loss of ferromagnetism at the film-substrate interface. In addition, the electronic structure of some characteristic PNMO samples is deeply analyzed using X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) measurements and compared with theoretical simulations. Our results show that the oxidation states of Ni and Mn ions are stabilized as Ni2+ and Mn4+, thus the ferromagnetism is mainly due to Ni2+-O-Mn4+ superexchange interactions, even in samples with poor ferromagnetic properties. XMCD results also make evident large variations on the spin and orbital contributions to the magnetic moment as the film's thickness decreases., This research was founded by the Spanish Ministry of Science and Innovation through the Severo Ochoa (CEX2019-000917-S), SPINCURIOX (RTI2018-099960-BI00), and OXISOT (PID2021-128410OB-I00) projects, which were co-financed by the European Regional Development Funds. ZK acknowledges the support of the Institute of Physics Belgrade through a grant from the Serbian Ministry of Education, Science, and Technological Development., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

Rare earth activated nitridosilicates have important applications as phosphor components in white light emitting diodes. (Oxy)nitridosilicates with beta-K2SO4 structure doped with Eu2+ are luminescent materials with emission wavelengths ranging from green to red under excitation with blue-UV light. Here we report the synthesis of isostructural NdEuSiO3N and the new oxynitridosilicate NdEuSiO3N by solid state reaction between Nd2O3, NdN, Eu2O3 or SrO and Si3N4 under N-2/H-2 gas at temperatures of 1300 degrees C and 1500 degrees C respectively. These compounds are the limiting compositions of the solid solution NdSr1-xEuxO3N crystallizing in the space group Pmnb with cell parameters a = 5.62293(1), b = 7.02285(1), c = 9.64784(2) A for NdEuSiO3N, and a = 5.63074(9), b = 7.01658(10), c = 9.65765(15) A for NdSrSiO3N. The Nd(3+)and Eu2+ cations in NdEuSiO3N or Nd3+ and Sr2+ in NdSrSiO3N show partial order in the two available crystallographic sites of coordination numbers 10 (M1) and 9 (M2), with strongly preferred occupancy of the larger divalent cations Eu2+ (77%) and Sr2+ (78%) for the M1 site, whereas the M2 site is preferred by Nd3+. Magnetic susceptibility measurements down to 2 K show that NdEuSiO3N is ferromagnetic with Tc = 3 K, in contrast to NdSrSiO3N that shows antiferromagnetic interactions at low temperatures. The band gaps of NdEuSiO3N and NdSrSiO3N determined from diffuse reflection spectroscopy are 2.37 and 3.72 eV respectively. NdEuSiO3N and the members of the solid solution NdSr0.98Eu0.02SiO3N and NdSr0.5Eu0.5SiO3N are orange-red light emitting luminescent materials, showing a broad emission band centered between 605 and 639 nm under excitation at 405 nm. These compounds are new phosphor materials with emission wavelengths shifted to the red with respect to the isostructural oxysilicates, which is induced by the introduction of nitride., This work was supported by the Ministerio de Ciencia e Innovación, Spain (PID2020-113805 ​GB-I00 and CEX2019-000917-S), and it has been developed under the PhD program in Materials Science of the UAB. We thank Alba for beam time provision and Dr. François Fauth for assistance in data collection at Alba. We acknowledge assistance from ICMAB-CSIC Scientific & Technological Services: X-Ray Diffraction (Mr. Joan Esquius), Thermal Analysis (Ms. Roberta Ceravola), Spectroscopic Techniques (Dr. Vega Lloveras) and Low Temperatures and Magnetometry (Dr. Bernat Bozzo). JRG acknowledges the AEI predoctoral fellowship PRE2018-085204., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S)., SI

Magnesium batteries have attracted great attention as an alternative to Li-ion batteries but still suffer from limited choice of positive electrode materials. V2O5 exhibits high theoretical capacities, but previous studies have been mostly limited to α-V2O5. Herein, we report on the β-V2O5 polymorph as a Mg intercalation electrode. The structural changes associated with the Mg2+ (de-) intercalation were analyzed by a combination of several characterization techniques: in situ high resolution X-ray diffraction, scanning transmission electron microscopy, electron energy-loss spectroscopy, and X-ray absorption spectroscopy. The reversible capacity reached 361 mAh g-1, the highest value found at room temperature for V2O5 polymorphs., The authors are grateful to the ALBA synchrotron for beamtime (proposal 2021024935). The Spanish Agencia Estatal de Investigación Severo Ochoa FUNFUTURE (CEX2019-000917-S) Excellence Centre distinction, the European Union’s Horizon 2020 research and innovation programme under grant agreement 824066 (E-MAGIC), and Junta de Andalucía (EMERGIA programme, grant 00153) are gratefully acknowledged. G.C.B.A., P.P., R.F.K., and J.C. were solely supported by the Joint Center for Energy Storage Research (JCESR) and Energy Innovation Hub funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences. I.R. acknowledges support from the National Science Foundation via grant DMR-2118020. This research used resources of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract DE-SC0012704. The authors acknowledge the free distribution of VESTA software, With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

Defects in crystalline structures play a vital role in their properties, so their proper characterization is essential to understanding and improving the behaviour of the materials. In this work, their presence in Ca4Fe9O17 has been analysed. Its structure exhibits three different iron coordination topologies and can be described as layers of corner-sharing FeO5 bipyramids stacked along the c axis together with layers of edge-sharing FeO6 octahedra, both being linked by FeO4 tetrahedra. The relative position of the FeO4 tetrahedra generates three possible stacking directions, which results in stacking faults when more than one is combined. Structural refinement using the Rietveld method in X-ray and neutron powder diffraction data was not possible due to significant mismatches between the observed and calculated integrated intensities for several peaks resulting from this atomic disorder. Selected area electron diffraction (SAED) and high-resolution scanning transmission electron microscopy (HR-STEM) images confirm the local defective nature of the material. The FAULTS software enabled a successful refinement of the structure considering a high concentration of planar defects, conferred by the existence of three possible stacking directions in the crystal structure, all of them confined in the basal plane., We acknowledge beamtime at ALBA synchrotron (proposal 2019073634) and ILL (EASY access system) and Dr François Fauth and Dr Clemens Ritter, respectively, for their help during data collection. ICMAB authors acknowledge Spain's Agencia Estatal de Investigación Severo Ochoa Program for Centers of Excellence in R&D (CEX2019-000917-S) and funding through grant PID2020-113805GB-I00. ICTS-CNME at UCM is acknowledged for offering access to STEM microscopy and expertise., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

Magnesium batteries have attracted great attention as an alternative to Li-ion batteries but still suffer from limited choice of positive electrode materials. V

Magnetic frustration results from competing magnetic interactions and leads to unusual ground states, ranging from non-collinear magnetic orders to spin liquids (SLs), opening the path to new physics and emerging properties. We report the engineered magnetic interaction design and synthesis of the new ternary nitride MnTa2N4 with a normal spinel structure, where the magnetic cations Mn2+ occupy exclusively the tetrahedral sites forming a diamond lattice. Although the magnetic interactions are strongly antiferromagnetic (θCW ≈ -140 K), a long-range magnetic order is not established, but a smooth magnetic anomaly is observed at T∗ ≈ 5.1 K, fingerprinting a large magnetic frustration. A short-range helicoidal magnetic order emerges at low temperatures. The ordered moment is ≈70% of the expected magnetic moment of Mn2+ ions and a large part (≈28%) of the spin entropy remains at 400 mK, signaling the coexistence of a helicoidal order with spin-glass-like or SL textures. First-principles calculations unveil an unexpected large direct Mn-Mn exchange interaction that balances the superexchange and accounts for the magnetic frustration. These findings open new avenues toward the design of quantum materials., This work was supported by the Ministerio de Ciencia e Innovación, Spain (PID2020-113805GB-I00, PID2020-118479RB-I00 (AEI/FEDER, EU), PGC2018-096955-B-C44 ,PGC2018-093863-B-C22, CEX2019-000917-S and MDM-2017-0767) and from Generalitat de Catalunya (2017SGR1377, 2017SGR581, 2017SGR1506, and 2017SGR1289). We thank Alba and ILL for beam time provision (experiments 2019023454 and 5-31-2713, respectively), Dr. François Fauth for assistance in data collection at Alba, and Dr. Bernat Bozzo (ICMAB-CSIC) for performing magnetic measurements. The authors acknowledge the use of Servicio General de Apoyo a la Investigación-SAI, Universidad de Zaragoza., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

Among metamagnetic materials, FeRh alloys are technologically appealing due to their uncommon antiferromagnetic-to-ferromagnetic metamagnetic transition which occurs at a temperature T* just above room temperature. Here, a controlled increase of T* (DT* B 20 8C) is induced in pre-selected regions of FeRh films via mechanical strain nanopatterning. Compressive stresses generated at the vicinity of predefined nanoindentation imprints cause a local reduction of the FeRh crystallographic unit cell parameter, which leads to an increase of T* in these confined micro-/nanometric areas. This enhances the stability of the antiferromagnetic phase in these localized regions. Remarkably, generation of periodic arrays of nanopatterned features also allows modifying the overall magnetic and electric transport properties across large areas of the FeRh films. This approach is highly appealing for the design of new memory architectures or other AFM-spintronic devices., Dr Patxi Lopez-Barbera is acknowledged for his assistance with the MOKE experiments. Vicente Garcia-Juez from Real Casa de la Moneda – Fabrica Nacional de Moneda y Timbre is acknowledged for his scientific advice. Dr Florencio Sa´nchez is acknowledged for the growth of the samples. Dr Bernat Bozzo is acknowledged for the electric transport characterization. ALBA synchrotron is acknowledged for the provision of beamtime at the MSPD (proposal number 2017092412) and CIRCE (proposal numbers 2017092462 and 2018022818) beamlines. Financial support from the Spanish Ministry of Economy and Competitiveness, through the ‘‘Severo Ochoa’’ Programme for Centres of Excellence in R&D (SEV-2015-0496 and SEV-2017-0706) and the MAT2017-85232-R, RTI2018-095303-B-C53. MAT2014-56063-C2-1-R, MAT2017-86357-C3-1-R (and associated FEDER) and MAT2015-73839-JIN projects, the Generalitat de Catalunya (2014 SGR 734 and 2017 SGR 292), AGAUR (2018 LLAV 00032 and 2019 LLAV 00050) and the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no. 665919 is acknowledged. This work was supported by the European Research Council under the SPIN-PORICS 2014-Consolidator Grant, Agreement No. 648454 and the MAGICSWITCH 2019-Proof of Concept Grant, Agreement No. 875018. ICN2 is funded by the CERCA Programme/Generalitat de Catalunya. I. F. acknowledges his RyC contract RYC-2017-22531. E. C. acknowledges the partial financial support from the National Science Centre of Poland (NCN) by the PRELUDIUM project UMO-2015/17/N/ST5/01988 and the SONATA Project No. UMO-2016/23/D/ST3/02121., We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).

Sustainability combined with high energy density prospects makes Fe-based oxides attractive as cathodes for calcium rechargeable batteries. This work presents a DFT evaluation of the CaFe2+nO4+n (0 < n < 3) family, for which both the average intercalation voltage and the theoretical specific capacity decrease with the increasing n value. The term n = 1/4, Ca4Fe9O17, meets the most appealing characteristics: a calculated average voltage of 4.16 V, a theoretical specific capacity of 230 mA h g−1 and the lowest energy barrier for Ca migration so far predicted for an existing oxide (0.72 eV). To overcome the previously reported synthesis difficulties, we employed a novel synthesis procedure in sealed quartz tubes followed by quenching in water. The XRD and SAED patterns of the prepared Ca4Fe9O17 powder reveal a certain degree of stacking defects along the c axis. Attempts to deinsert Ca ions from Ca4Fe9O17 by chemical means (NO2BF4 in ACN) and in electrochemical Ca cells were unsuccessful, although some hints of oxidation are observed in Li cells with the LP30 electrolyte. The suitability of Ca4Fe9O17 as a Ca cathode is pending further studies utilizing Ca-electrolytes with high anodic stability., This research was funded by the European Union’s Horizon 2020 research and innovation programme H2020 FETOPEN-1- 2016-2017 (CARBAT, grant agreement no. 766617). The authors are grateful for access to the computational facilities from Universidad de Oviedo (MALTA-Consolider cluster), to ALBA synchrotron for the provision of beam time and to Dr F. Fauth for his help during data collection and also acknowledge Dr. J. Oró-Solé for assistance with electron diffraction and Dr. Clemens Ritter for helpful discussions. ICMAB authors are also grateful to the Spanish Ministry for Economy, Industry and Competitiveness Severo Ochoa Programme for Centres of Excellence in R&D (SEV-2015-0496).

The formation of the crystalline organic polymer (OP) islands on top of double perovskite ferromagnetic La2Ni1–xMn1+xO6 (x = 0.4) thin films by RF sputtering is reported. The presence of randomly ramified organic polymer islands for film grown on top of SrTiO3 and LaAlO3 substrates suggest the fractal growth. The stability of fractal OP islands is tested by an in-situ oxygen annealing process as function of the annealing temperature. The evolution of the fractal structure of OP islands is followed in parallel with the evolution of structural and magnetic properties of LNMO thin films. The modification of the manganese valence state due to the presence of organic polymer fractals is studied by means of X-ray photoemission microscopy., This work has received funding from the European Union's Horizon 2020 research and innovation under the Marie Sklodowska-Curie grant agreement No. 645658 (DAFNEOX Project). A.P. and Z.K. thank Senzor-INFIZ (Serbia) for the cooperation provided during their respective secondments. E. P.-M. acknowledge financial support from the Spanish Ministry of Economy and Competitiveness through the “Severo Ochoa” Programme for Centers of Excellence in R&D (CEX2019-000917-S), and project MAT2015-71664 and SPINCURIOX (RTI2018-099960-B-I00). M. Š. and Z. K. acknowledge the support of the Serbian Ministry of Education, Science and Technological Development (Projects No III45018). This work has been performed in the framework of the PhD program of the Universitat Autonoma de Barcelona (UAB).

The development of new synthetic methodologies of perovskite oxynitrides is challenging but necessary for the search of new compounds and the investigation of new properties. Here, we report a new method of preparation of the perovskite LaTaON

Spin Hall magnetoresistance (SMR) is used to study interfacial magnetic features in La2CoMnO6 (LCMO)/Pt bilayers. LCMO is a ferromagnetic insulator with a Curie temperature Tc = 250 K and a strong magnetic anisotropy that can be tuned by microstructural strain. However, SMR measurements do not show any dependence on the strained state of the LCMO films. In addition, contrary to what may be expected, SMR signal persists above TC exhibiting a strong magnetic field dependence well above the saturation of the magnetization while the typical hysteresis on crossing H = 0 is absent. All these results suggest that the uppermost LCMO interfacial layers are magnetically uncoupled from the rest of the LCMO film and they do not show long range magnetic ordering. This fact is confirmed by a complete scanning transmission electron microscopy study of the interface that makes evident that the last atomic layers of the LCMO film do not contain Co and have a LaMnO3+δ simple perovskite-like structure with the last atomic layer being lanthanum oxide. The analysis of the experimental results according to recent SMR theories indicates, in fact, that the LCMO interfacial layer behaves as a 2D Heisenberg ferromagnet., The authors acknowledge financial support from the Spanish Ministry of Science and Innovation through Severo Ochoa (CEX2019-000917-S), Maria de Maeztu (CEX2020-001038-M), and SPINCURIOX (RTI2018-099960-BI00) and SCARFACE (RTI2018-094861-B-I00) projects co-financed by the European Regional Development Funds. The authors acknowledge the SEM-FIB microscopy service of the Universidad de Málaga and the ICTS-CNME for offering access to their instruments and expertise. S.M.-R. thanks the hospitality of CIC-nanoGUNE group. J.M.G.-P. and M.X.A.-P. thank the Spanish MICINN for a Ph.D. fellowship (Grant Nos. BES-2016-077301 and PRE-2019-089833, respectively). S.C. acknowledges support from the European Commission for a Marie Sklodowska-Curie Actions individual fellowship (Grant No. 796817-ARTEMIS)., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

Complex oxide thin films grown by using chemical methods are of strong interest because of their low-cost, environment friendly fabrication and easy scalability. However, their introduction in spintronic applications or magnetic devices is still scarce mainly because of concerns regarding their interfacial quality. Here, we report on the preparation by polymer-assisted-deposition (PAD) of epitaxial La0.92MnO3 (LMO) thin films. We demonstrate that ferromagnetic conducting LMO thin films with smooth surfaces (rms ∼ 0.2 nm) can be prepared by PAD. By means of temperature-dependent broadband ferromagnetic resonance (FMR), we show that the LMO film exhibits a four-fold in-plane anisotropy, with [110] being the easy in-plane axis, compatible with strain release from the rhombohedral bulk phase. It has also been found that the isotropic Gilbert damping, α, determined from the broadening of the FMR linewidth, does not show a relevant extrinsic contribution and it exhibits an intraband-like temperature dependence, i.e. it increases as temperature decreases. By capping LMO thin films with a 10 nm thick Pt layer deposited ex situ, damping is substantially enhanced, from a value at 150 K of αLMO ∼ 1 × 10−2 for the bare LMO film to αLMO+Pt ∼ 2.5 × 10−2 for the Pt capped film. This strong increase of magnetic damping is indicative of the transfer of spin momentum from LMO to the Pt layer by spin pumping. Our results demostrate that LMO films grown by PAD may be used as efficient spin source systems in heterostructures for spintronic devices., We acknowledge financial support from the Spanish Ministry of Science, Innovation and Universities through Severo Ochoa (SEV-2015-04969), HETEROCS (MAT2015-71664-R), SUMATE (RTI2018-095853-B-C21) and SPINCURIOX (RTI2018-099960-B-I00) projects cofinanced by the European Regional Development Fund. This project has received funding from the European Union through the Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 645658 (DAFNEOX Project) and through the FEDER Program. Hailin Wang acknowledges financial support from the China Scholarship Council (CSC). This work has been performed in the framework of the PhD programme in Materials Science of the Universitat Autònoma de Barcelona, through the China Scholarships Council (CSC)/Universitat Autònoma de Barcelona (UAB) Joint Scholarship. Authors thank Dr B. Bozzo and F. J. Campos for their technical support during magnetic and X-ray diffraction measurements. We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).

The control of the spontaneous formation of nanostructures at the surface of thin films is of strong interest in many different fields, from catalysts to microelectronics, because surface and interfacial properties may be substantially enhanced. Here, we analyze the formation of nickel oxide nanocuboids on top of La2Ni1−xMn1+xO6 double perovskite ferromagnetic thin films, epitaxially grown on SrTiO3 (001) substrates by radio-frequency (RF) magnetron sputtering. We show that, by annealing the films at high temperature under high oxygen partial pressure, the spontaneous segregation of nanocuboids is enhanced. The evolution of the structural and magnetic properties of the films is studied as a function of the annealing treatments at different temperatures. It is shown that the formation of NiOx nanocuboids leads to a nanostructured film surface with regions of locally different electrical transport characteristics., We acknowledge financial support from the Spanish Ministry of Science, Innovation and Universities through Severo Ochoa Program (CEX2019-000917-S) and RTI2018-099960-B-I00 (SPINCURIOX) and funding from the European Union’s Horizon 2020 research and innovation program under the Marie-Sklodowska-Curie grant agreement No. 645658 (DAFNEOX Project) and FEDER Program. Z.K. acknowledge the support of the Serbian Ministry of Education, Science and Technological Development (III45018). This work has been performed in the framework of the PhD program of the Universitat Autonoma de Barcelona (UAB).

1D Ca3Co2–zMzO6 (M = Co z = 0, M = Mn z = 1, and M = Fe z = 0.4) were prepared and tested electrochemically. While the iron-containing phase was not found to be active, the iron- and manganese-containing phases were found to be potentially interesting as positive electrode materials for calcium metal-based high-energy battery technologies and were investigated by operando synchrotron X-ray diffraction. Results indicate that electrochemically driven calcium deintercalation from the crystal structure (ca. 0.7 mol per formula unit) takes place upon oxidation in both cases. The oxidized phases have incommensurate modulated crystal structures with the space group R 3m(00γ)0s and a = 9.127(1) Å, c1 = 2.4226(3) Å and c2 = 4.1857(3) Å, and γ = 0.579 (M = Co) and a = 9.217(1) Å, c1 = 4.9076(4) Å and c2 = 4.3387(4) Å, and γ = 1.139 (M = Mn), which exhibit differences due to the presence of manganese and Mn/Co ordering. The degree of calcium re-intercalation within the structure was found to be extremely limited, if any. Complementary experiments carried out in lithium cells did not show any reversibility either, thus pointing at intrinsic structural/migration constraints in the oxidized phase rather than slow kinetics of high desolvation energies associated with divalent ion charge carriers., The authors are grateful to Alexandre Ponrouch and ALISTORE-ERI members for helpful discussions and to ALBA synchrotron for beamtime (proposal 2019073634). ICMAB-CSIC members thank the Spanish Agencia Estatal de Investigación Severo Ochoa Programme for Centres of Excellence in R&D (CEX2019-000917-S). D.M. acknowledges the EC for a H2020 MSCA-IF grant (contract number 743439). R.G.H. acknowledges the EC for a H2020 MSCADOC-FAM grant (contract number 754397).

Clarkson, J. D. et al., The ability to control a magnetic phase with an electric field is of great current interest for a variety of low power electronics in which the magnetic state is used either for information storage or logic operations. Over the past several years, there has been a considerable amount of research on pathways to control the direction of magnetization with an electric field. More recently, an alternative pathway involving the change of the magnetic state (ferromagnet to antiferromagnet) has been proposed. In this paper, we demonstrate electric field control of the Anomalous Hall Transport in a metamagnetic FeRh thin film, accompanying an antiferromagnet (AFM) to ferromagnet (FM) phase transition. This approach provides us with a pathway to “hide” or “reveal” a given ferromagnetic region at zero magnetic field. By converting the AFM phase into the FM phase, the stray field, and hence sensitivity to external fields, is decreased or eliminated. Using detailed structural analyses of FeRh films of varying crystalline quality and chemical order, we relate the direct nanoscale origins of this memory effect to site disorder as well as variations of the net magnetic anisotropy of FM nuclei. Our work opens pathways toward a new generation of antiferromagnetic – ferromagnetic interactions for spintronics., Te work at Berkeley was supported in part by FAME, one of six centers of STARnet, a Semiconductor Research Corporation program sponsored by MARCO and DARPA was supported by the SRC-FAME program. Financial support by the Spanish Government (Project MAT2014-56063-C2-1-R, MAT2015-73839-JIN, MAT2017- 85232-R and associated FEDER) and Generalitat de Catalunya (2014 SGR 734) is acknowledged. ICMAB-CSIC authors acknowledge fnancial support from the Spanish Ministry of Economy and Competitiveness, through the “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV- 2015-0496). IF acknowledges Juan de la Cierva – Incorporación postdoctoral fellowship (IJCI-2014-19102) from the Spanish Ministry of Economy and Competitiveness of Spanish Government. XMCD-PEEM experiments were performed at CIRCE beamline at ALBA Synchrotron with the acknowledged collaboration of ALBA staf. Partial fnancial support from the 2014-Consolidator Grant "SPIN-PORICS" (Grant Agreement nº 648454) from the European Research Council is acknowledged. XM acknowledges support from the Grant Agency of the Czech Republic Grant no. 14-37427. Work at ORNL was sponsored by the Laboratory Directed Research and Development (LDRD) Programs of ORNL managed by UT-Battelle, LLC. Work at CSUN was supported by NSF under Grant No. 1205734, NSF Partnerships for Research and Education in Materials (PREM), and by NSF under Grant No. 1160504 NSF Nanosystems Engineering Research Center for Translational Applications of Nanoscale Multiferroic Systems (TANMS).

The development of new synthetic methodologies of perovskite oxynitrides is challenging but necessary for the search of new compounds and the investigation of new properties. Here, we report a new method of preparation of the perovskite LaTaON2 that has been investigated as a pigment and photocatalyst for water splitting. The synthesis proceeds through the solid-state reactions under N2 at 1500 °C between La2O3, LaN, and Ta3N5 or between LaN and TaON, which are completed after 3 h and lead to sintered, highly crystalline samples with particle sizes up to 1 μm. Nitrogen-deficient samples LaTaO1+xN2-x with x ≤ 0.35 are prepared by changing the N/O ratio in the mixture of reactants. Electron diffraction, synchrotron diffraction, and neutron diffraction studies on stoichiometric and nitrogen-deficient compounds indicate that they crystallize in the monoclinic space group I2/m with lattice parameters for LaTaON2 of a = 5.71458(7), b = 8.05987(10), c = 5.74772(6) Å, and β = 89.982(3)°. The three anion sites of the I2/m structure are partially occupied by oxygen and nitrogen, with a preference of nitride for two positions with occupancies of 77 and 88%. This anion distribution is different from that reported in previous studies of samples prepared by ammonolysis at lower temperature, suggesting that the synthesis conditions affect the anion order of this perovskite. Optical measurements indicate a band gap of about 1.9 eV, which is close to that observed in samples prepared by other methods. The determined dielectric permittivity for LaTaON2 εr ≈ 200, reported for the first time for a highly nitrided pseudocubic perovskite, is similar to that observed in perovskites with one nitrogen per formula., This work was supported by the Ministerio de Ciencia e Innovación, Spain [MAT2017-86616-R, MAT2017-85232-R, PID2019-107727RB-I00, PID2020-113805GB-I00, PID2020-118479RB-I00, and CEX2019-000917-S], from Generalitat de Catalunya (2017SGR1377 and 2017SGR581) and from CSIC through the i-LINK (LINKA20338) program. The authors thank Alba and ILL for beam time provision (experiments 2017092391 and 5-21-1113, respectively), Dr. François Fauth for assistance in data collection at Alba, and Dr. Bernat Bozzo (ICMAB-CSIC) for performing electrical measurements. The project was also supported by a 2020 Leonardo Grant for Researchers and Cultural Creators, BBVA Foundation. I.F. acknowledges the Ramón y Cajal contract RYC-2017-22531 and JRG acknowledges the AEAT predoctoral fellowship PRE2018-085204., With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).

The annealing process is an important step common to epitaxial films prepared by chemical solution deposition methods. It is so because the final microstructure of the films can be severely affected by the precise features of the thermal processing. In this work we analyze the structural and magnetic properties of double perovskite La2CoMnO6 and La2NiMnO6 epitaxial thin films prepared by polymer-assisted deposition (PAD) and crystallized by rapid thermal annealing (RTA). It is found that samples prepared by RTA have similar values of saturation magnetization and Curie temperature to their counterparts prepared by using conventional thermal annealing (CTA) processes, thus indicating low influence of the heating rates on the B-B’ site cationic ordering of the A2BB’O6 double perovskite structure. However, a deeper analysis of the magnetic behavior suggested some differences in the actual microstructure of the films., This research was founded by the Spanish Ministry of Science, Innovation and Universities through Severo Ochoa (SEV-2015–04969) and Severo Ochoa FUNFUTURE (CEX2019-000917-S), SUMATE (RTI2018-095853-B-C21), and SPIN-CURIOX (RTI2018-099960- B-100) projects co-financed by the European Regional Development Fund. Hailin Wang acknowledges financial support from the China Scholarship Council (CSC). This work has been performed in the framework of the Ph.D. program in Materials Science of the Universitat Autònoma de Barcelona (UAB), through the CSC/UAB Joint Scholarship.

Non-centrosymmetric polar compounds have important technological properties. Reported perovskite oxynitrides show centrosymmetric structures, and for some of them high permittivities have been observed and ascribed to local dipoles induced by partial order of nitride and oxide. Reported here is the first hexagonal perovskite oxynitride BaWON

The temperature dependence of the spin pumping process in Fe80Ni20 (Py)/Pt bilayers is analyzed for different Pt capping layer thickness. Samples have been grown by means of dc magnetron sputtering, at room temperature, on top of Si substrates. In order to get an optimized interface between the Py and the Pt layers, the Pt capping layers were deposited In situ. The values of the damping constant, α, obtained for the Py alone samples, around 0.007 at RT, make evident the good quality of the samples. The increase of α due to spin pumping into the Pt layer is clearly appreciated; α values in Py/Pt bilayers are twice the value in Py alone. Spin pumping is confirmed by direct measurements of the inverse spin Hall effect (ISHE) voltage signal (VISHE) measured across the samples. To separate ISHE and spin rectification contributions to VISHE the line shape analysis method has been used and the conditions for its applicability thoroughly discussed. VISHE increases almost linearly on lowering temperature for all the frequencies investigated and smoothly increases as frequency decreases showing roughly a linear dependence with the inverse of the frequency. The Pt layer thickness dependence of α and VISHE suggest a low interfacial spin mixing conductance and high spin memory loss., We acknowledge financial support from the Spanish Ministry of Science, Innovation and Universities through Severo Ochoa Program (SEV-2015-04969), MAT2015-71664-R and RTI2018-099960-B-I00 and funding from the EU (European Union) Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No. 645658 (DAFNEOX Project) and FEDER Program.

Sustainability combined with high energy density prospects makes Fe-based oxides attractive as cathodes for calcium rechargeable batteries. This work presents a DFT evaluation of the CaFe2+nO4+n (0n3) family, for which both the average intercalation voltage and the theoretical specific capacity decrease with the increasing n value. The term n = 1/4, Ca4Fe9O17, meets the most appealing characteristics: a calculated average voltage of 4.16 V, a theoretical specific capacity of 230 mA h g-1 and the lowest energy barrier for Ca migration so far predicted for an existing oxide (0.72 eV). To overcome the previously reported synthesis difficulties, we employed a novel synthesis procedure in sealed quartz tubes followed by quenching in water. The XRD and SAED patterns of the prepared Ca4Fe9O17 powder reveal a certain degree of stacking defects along the c axis. Attempts to deinsert Ca ions from Ca4Fe9O17 by chemical means (NO2BF4 in ACN) and in electrochemical Ca cells were unsuccessful, although some hints of oxidation are observed in Li cells with the LP30 electrolyte. The suitability of Ca4Fe9O17 as a Ca cathode is pending further studies utilizing Ca-electrolytes with high anodic stability.

Double perovskite structure (A2BB′O6) oxides exhibit a breadth of multifunctional properties with a huge potential range of applications in fields as diverse as spintronics, magneto‐optic devices, or catalysis, and most of these applications require the use of thin films and heterostructures. Chemical solution deposition techniques are appearing as a very promising methodology to achieve epitaxial oxide thin films combining high performance with high throughput and low cost. In addition, the physical properties of these materials are strongly dependent on the ordered arrangement of cations in the double perovskite structure. Thus, promoting spontaneous cationic ordering has become a relevant issue. In this work, our recent achievements by using polymer‐assisted deposition (PAD) of environmentally friendly, water‐based solutions for the growth of epitaxial ferromagnetic insulating double perovskite La2CoMnO6 and La2NiMnO6 thin films on SrTiO3 and LaAlO3 single‐crystal substrates are presented. It is shown that the particular crystallization and growth process conditions of PAD (very slow rate, close to thermodynamic equilibrium conditions) promote high crystallinity and quality of the films, as well as favors spontaneous B‐site cationic ordering., We acknowledge financial support from the Spanish Ministry of Science, Innovation and Universities through Severo Ochoa (SEV‐2015–04969), SUMATE (RTI2018‐095853‐B‐C21), and SPINCURIOX (RTI2018‐099960‐B‐I00) projects co‐financed by the European Regional Development Fund. Hailin Wang acknowledges financial support from the China Scholarship Council (CSC). This work has been performed in the framework of the Ph.D. program in Materials Science of the Universitat Autònoma de Barcelona (UAB), through the CSC/UAB Joint Scholarship. The authors thank the ALBA Synchrotron (Spain) for the provision of beamtime. The authors also thank Dr. B. Bozzo and F. J. Campos for their technical support during magnetic and X‐ray diffraction measurements.

Non‐centrosymmetric polar compounds have important technological properties. Reported perovskite oxynitrides show centrosymmetric structures, and for some of them high permittivities have been observed and ascribed to local dipoles induced by partial order of nitride and oxide. Reported here is the first hexagonal perovskite oxynitride BaWON2, which shows a polar 6H polytype. Synchrotron X‐ray and neutron powder diffraction, and annular bright‐field in scanning transmission electron microscopy indicate that it crystalizes in the non‐centrosymmetric space group P63mc, with a total order of nitride and oxide at two distinct coordination environments in cubic and hexagonal packed BaX3 layers. A synergetic second‐order Jahn–Teller effect, supported by first principle calculations, anion order, and electrostatic repulsions between W6+ cations, induce large distortions at two inequivalent face‐sharing octahedra that lead to long‐range ordered dipoles and spontaneous polarization along the c axis. The new oxynitride is a semiconductor with a band gap of 1.1 eV and a large permittivity., This work was supported by the Ministerio de Ciencia e Innovación, Spain (MAT2017‐86616‐R, MAT2017‐85232‐R, SEV‐2015‐0496, MDM‐2017‐0767, PGC2018‐096955‐B‐C44 and PGC2018‐093863‐B‐C22) and the Generalitat de Catalunya (2017SGR1377, 2017SGR581, 2017SGR1506 and 2017SGR1289). We thank Alba and ILL (experiments 2018082958 and 5‐23‐721, https://doi.org/10.5291/ILL‐DATA.5‐23‐721) for beam time provision, and Dr. François Fauth for assistance in data collection at Alba. I.F and J.G. acknowledge the Ramon y Cajal contracts RYC‐2017‐22531 and RYC‐2012‐11709. S.C. was supported by FONDECYT, Chile (project 11171063). ICTS‐CNME at UCM is acknowledged for offering access to STEM and expertise.

A comparative study of the electrochemical intercalation of Ca2+ and Mg2+ in layered TiS2 using alkylcarbonate-based electrolytes is reported, and for the first time, reversible electrochemical Ca2+ insertion is proved in this compound using both X-ray diffraction and differential absorption X-ray tomography at the Ca L2 edge. Different new phases are formed upon M2+ insertion that are structurally characterized, their amount and composition being dependent on M2+ and the experimental conditions. The first phase formed upon reduction is found to be the result of an ion-solvated intercalation mechanism, with solvent molecule(s) being cointercalated with the M2+ cation. Upon further reduction, new non-cointercalated calcium-containing phases seem to form at the expense of unreacted TiS2. The calculated activation energy barriers for Ca2+ migration in TiS2 (0.75 eV) are lower than those previously reported for Mg (1.14 eV) at the dilute limit and within the CdI2 structural type. DFT results indicate that the...

The electrochemical oxidation of a transition metal oxide through calcium extraction is achieved for the first time. The 1D framework of Ca3Co2O6 is maintained upon oxidation and the new phase formed exhibits a modulated structure. The process occurs at high potential and is partially reversible, which opens prospects for a calcium battery proof-of-concept.

A high-pressure metastable orthorhombic phase of SrIrO3 perovskite has been epitaxially stabilized on several substrates (DyScO3, GdScO3, NdScO3 and SrTiO3) in the form of thin monocrystalline layers with (110) surface orientation. The unit-cell parameters of the pseudomorphic thin SrIrO3 layers depend on the biaxial strain imposed by the various substrates due to the different lattice mismatches of the particular substrate and the bulk orthorhombic SrIrO3 structure. Using X-ray diffractometry, it is shown that both compressive and tensile strain increase the lattice parameters a and b, while the angle γ scales with the applied strain, being smaller or larger than 90° for compressive or tensile strain, respectively, resulting in a small monoclinic distortion of the layer unit cell. Owing to the similarity of the substrate and layer lattices, the diffraction signals from the two structures overlap partially, which complicates structure determination by standard refinement methods using measured integrated intensities. The measured signal is composed of two interfering components corresponding to the waves diffracted by the substrate and by the layer, where the first component is calculated exactly using the known substrate structure, while the second one is determined by the unknown unit-cell parameters of the layer. The unit-cell parameters were refined in order to fit the experimental data with the simulation. The fractional coordinates of the atoms in the unit cell resulting from the fit are similar to those in the bulk structure.

A wet-chemical synthesis process was designed to obtain reproducible single-phase multiferroic BiFeO

A wet-chemical synthesis process was designed to obtain reproducible single-phase multiferroic BiFeO3 nanoparticles. The phase purity, single crystallinity, and size of the nanoparticles are confirmed through the analysis of X-ray diffraction patterns, Raman spectroscopy, and high resolution transmission electron microscopy experiments. Crystal nucleation happens within the amorphous-rich area in multiple seeds, leading to the formation of single crystalline nanoparticles with no preferential faceting. Crystallization mechanisms of BiFeO3 nanoparticles were investigated following the Kissinger–Akahira–Sunose approach, indicating that two crystallization steps are responsible of the complete BiFeO3 nanoparticle formation. The first crystallization step involves a maximum of 70% of the final crystal volume, arising from nanocrystal nucleation and growth. The second step occurs above this threshold crystal volume fraction, and it is related to the nanocrystallite coalescence process. Analysis of the thermodynamic process of the crystallization of BiFeO3 nanoparticles following Ostwald rules suggests a relatively low energy barrier for crystal nucleation, highlighting that phase pure, single crystalline BiFeO3 nanoparticles are obtained using the present optimized wet-chemical synthesis process, with temperatures as low as 450 °C., This work was supported by the IDEXLYON (ANR-16-IDEX-0005) FERLIGHT project from the Université de Lyon. J.G., D.L. and I.C.I. express thanks for the FNR funding provided by the INTER/Mobility FOXCAT Project No. 15/9887562. We thank Nagy Valanoor for fruitful discussions

The topotactic nitridation of cation ordered, tetragonal Sr2FeMoO6 in NH3 at moderate temperatures leads to cubic, Fm3[combining macron]m double perovskite oxynitride Sr2FeMoO4.9N1.1 where double-exchange interactions determine ferromagnetic order with TC ≈ 100 K. Substitution of oxide by nitride induces bond asymmetries and local electronically driven structural distortions, which combined with Fermi level lowering restricts charge itinerancy to confined regions and preclude spontaneous long-range magnetic order. Under a magnetic field, ferromagnetic correlations expand, favoring charge delocalization and a negative magnetoresistance is observed.

The topotactic nitridation of cation ordered, tetragonal Sr2FeMoO6 in NH3 at moderate temperatures leads to cubic, Fm[3 with combining macron]m double perovskite oxynitride Sr2FeMoO4.9N1.1 where double-exchange interactions determine ferromagnetic order with TC ≈ 100 K. Substitution of oxide by nitride induces bond asymmetries and local electronically driven structural distortions, which combined with Fermi level lowering restricts charge itinerancy to confined regions and preclude spontaneous long-range magnetic order. Under a magnetic field, ferromagnetic correlations expand, favoring charge delocalization and a negative magnetoresistance is observed., This work was supported by the Spanish Ministerio de Ciencia, Universidades e Investigación, Spain (Projects MAT2017-86616-R, MAT2017-85232-R, MAT2015-71664-R, MAT2015-67593-P and ENE2015-63969) and by Generalitat de Catalunya (2017SGR1377, 2017SGR581). ICMAB acknowledges financial support from MINECO through the Severo Ochoa Program (SEV-2015-0496). We thank the Institut Laue Langevin (ILL) and Alba synchrotron for the provision of beam time., We acknowledge support of the publication fee by the CSIC Open Access Support Initiative through its Unit of Information Resources for Research (URICI)

In this work we report on the epitaxial growth of La2NiMnO6 double perovskite thin films on top of (001) oriented SrTiO3 substrates by RF magnetron sputtering. The influence of oxygen pressure (PO2 ) and growth temperature on the microstructure, stoichiometry of the films, and magnetic and transport properties is thoroughly investigated. It is found that high oxygen pressure promotes the growth of stoichiometric films, with a Ni/Mn ratio almost equal to 1. However, these films exhibit poor ferromagnetic properties with respect to the expected optimum values corresponding to ferromagnetic ordering mediated by superexchange interaction between Mn4+ and Ni2+ according to the Goodenough-Kanamori rules. Most interestingly, films grown at low PO2 exhibit Ni/Mn ratios below 1, but ferromagnetic properties close to the optimal ones. The valence balance between Ni and Mn ions in nonstoichiometric sample has been elucidated by X-ray absorption spectroscopy. The results indicate that Ni deficiency plays a crucial role in the puzzling insulating ferromagnetic behavior observed in nonstoichiometric samples., M.B.-S., Ll.B., F.S., B.B., C.F., B.M., and A.P. acknowledge financial support from the Spanish Ministry of Economy and Competitiveness through the “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV-2015-0496), and Project MAT2015-71664-R. This work has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Grant Agreement No. 645658 (DAFNEOX Project). Z.K. acknowledge the support of the Serbian Ministry of Education, Science and Technological Development (III45018). Authors thank ALBA synchrotron (Spain) for the provision of beamtime., We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI).

Layered CaTaN2 and MgTa2N3 and cubic Mg2Ta2N4 were prepared by direct solid state reaction from the binary nitrides Ta3N5 and A3N2 (A: Mg, Ca). CaTaN2 showed a slight Ca deficiency (0.11 moles per formula), and a monoclinic distortion from previously reported R3̅m symmetry, with space group C2/m and cell parameters a = 5.4011(2), b = 3.1434(1), c = 5.9464(2) Å and β = 107.91(3)°. Ca2+ and Mg2+ deintercalation was investigated in the three compounds both chemically and electrochemically. No significant Mg2+ extraction could be inferred for MgTa2N3 and Mg2Ta2N4, neither after reaction with NO2BF4 nor after electrochemical oxidation at 100 °C in alkyl carbonate electrolytes. Rietveld refinement of the X-ray powder diffraction pattern of chemically oxidized Ca0.89TaN2 indicates a decrease of the Ca content to 0.34 concomitant to the disappearance of the monoclinic distortion and expansion of the interlayer space from 5.658 to 5.762 Å, space group R3̅m and cell parameters a = 3.1103(1) and c = 17.287(1) Å. Deintercalation in this compound was also achieved electrochemically at 100 °C. Results of density functional theory calculations seem to indicate that reaction mechanisms for CaTaN2 oxidation additional and/or alternative to deintercalation are taking place, which is likely related to the loss of crystallinity observed upon oxidation and the irreversibility of the process.

International audience; Vanadium pentoxide has been investigated for multivalent ion battery technologies but the structural characterization of inserted phases is poor, and conflicting reports exist in the literature. This study presents a critical overview of controversial aspects related to Mg and Ca insertion in α-V2O5 under diverse conditions by combined electrochemical and ex-situ XRD experiments. Galvanostatic tests are carried out in dry and wet alkyl carbonate-based electrolytes at RT and 100 °C. The formation of protonated phases with negligible divalent ion content if any is evidenced by Rietveld refinements of the XRD data, unambiguously dismissing the presence of AV2O5 (A: Mg, Ca) as electrochemical reduction products. Furthermore, thermal instability of V2O5 at 100 °C in alkyl carbonate solvents is demonstrated by XRD and TEM analysis and the formation of an orthorhombic phase with increased a parameter, most likely due to degradation favored by both water and temperature, is observed for both Mg and Ca. In order to assess the feasibility of the reverse reaction, fully intercalated AV2O5 (A = Ca, Mg) phases were also prepared by solid state reaction and oxidation attempted both electrochemically and chemically without evidence of any significant amount of Mg2+ or Ca2+ extraction, further corroborating the sluggish diffusion kinetics of divalent cations in α-V2O5.

This paper assesses the instrumental resolution of a mechanical extensometer in light of its recent automatisation. The instrument takes advantage of the moire phenomenon of optical interference to measure angular rotation in two perpendicular planes and displacement in three dimensions. Our assessment systematically defines an analytical solution for the complete interpretation of a generic moire pattern and a set of mathematical approximations for the moire patterns used to measure rotation and displacement. The ultimate sensitivity of the automated instrument is determined on the basis of a generic least square differences fitting procedure while the instrumental resolution is defined on the basis of realistic, rather than optimal, scenarios: the resolution of the rotation measurements are in the order of 8.7*10-5 rad while the resolution of the displacement measurements are better than 5 μm. This assessment represents the first step towards a global numerical repository for processed data recorded by the automated extensometers.

Density functional theory (DFT) calculations are used to investigate the basic electrochemical characteristics of Si-based anodes in calcium ion batteries (CIBs). The calculated average voltage of Ca alloying with fcc-Si to form the intermetallic CaxSi phases (0.5 b x ≤ 2) is of 0.4 V, with a volume variation of 306%. Decalciation of the lower Ca content phase, CaSi2, is predicted at an average voltage between 0.57 V (formation of Si-fcc, 65% volume variation) and 1.2 V (formation of metastable deinserted-Si phase, 29% volume variation). Experiments carried out in conventional alkyl carbonate electrolytes show evidence that electrochemical “decalciation” of CaSi2 is possible at moderate temperatures. The decalciation of CaSi2 is confirmed by different characterization techniques., We are grateful to the Toyota Battery Research division at Higashi Fuji (M6) for financial support. Diffraction experiments were performed at MSPD beamline at ALBA Synchrotron and the collaboration of François Fauth (ALBA staff) is sincerely acknowledged. ICMAB authors acknowledge the Spanish Ministry of Economy and Competitiveness (“Severo Ochoa” Programme for Centres of Excellence in R&D (SEV- 2015-0496)).

In this work we report on the controlled fabrication of a self-assembled line network in highly epitaxial BiFeO3 thin films on top of LaAlO3 in the kinetically limited grown region by RF sputtering. As previously shown in the case of manganite thin films, the remarkable degree of ordering is achieved using vicinal substrates with well-defined step-terrace morphology. Nanostructured BiFeO3 thin films show mixed-phase morphology. Besides typical formation following (100) and (010) axes, some mixed phase nanodomains are detected also in-between the regular line network. These particular microstructures open a playground for future applications in multiferroic nanomaterials., This work has received funding from the European Union’s Horizon 2020 research and innovation under the Marie Sklodowska-Curie grant agreement No. 645658 (DAFNEOX Project). A.P., V. F. and Z.K. thank Senzor-INFIZ (Serbia) for the cooperation provided during their respective secondments. E. P.-M. acknowledge financial support from the Spanish Ministry of Economy and Competitiveness through the “Severo Ochoa” Programme for Centres of Excellence in R&D (SEV-2015- 0496), and project MAT2015-71664 and SPINCURIOX (RTI2018-099960-B-I00). N. L., M. S., Z. K. and Z.V.P. acknowledge the support of the Serbian Ministry of Education, Science and Technological Development (Projects No III45018).