Ruddlesden-Popper Series Research Articles

Simulation of diffraction patterns for Ruddlesden–Popper (RP) tetragonal structures with RP faults

A theoretical analysis of diffraction patterns was performed for two representatives of layered perovskite-type tetragonal phases of the Ruddlesden–Popper series (RP) with the general formula A n+1 B n O3n+1 (n = 1, 2), which contain RP faults (layer alternation defects) in a wide range of concentrations. The results of theoretical calculations can be used in the future for correct interpretation of X-ray powder diffraction experimental data and for quantitative estimation of the deviation from stoichiometry and structural perfection of this type of compound.

Anomalous Behavior in Dark-Bright Splitting Impacts the Biexciton Binding Energy in (BA)2(MA)n-1PbnBr3n+1 (n = 1-3).

Two-dimensional Ruddlesden-Popper series are an excellent system for tuning physical properties of the perovskite by controlling the layer number (n). For instance, bandgap and exciton binding energies of the series gradually increase upon reducing n via enhanced quantum and dielectric confinements. Here, we present findings that challenge the anticipated trend in electron-hole exchange interaction within (BA)2MAn-1PbnBr3n+1 (n = 1-3), which causes spin-dependent exciton level splitting into bright and dark states, where the latter is partially visible near the surface of the Br-based two-dimensional Ruddlesden-Popper series. Contrary to expectations, the smallest gap between bright and dark exciton levels is observed from n = 2 at 10 K. This anomaly results in the strongest biexciton binding between two dark excitons occurring at n = 2, rather than at n = 1 as initially hypothesized. The observed anomaly arises from a phase transition induced by octahedral tilting occurring only for n = 2 near 100 K as confirmed by temperature-dependent optical and X-ray diffraction measurements. Our results show that Coulomb interaction need not vary gradually with n, which can impact the optoelectronic properties of the Ruddlesden-Popper series.

Weak antilocalization and sign inversion of magnetoresistance on CaRuO3 epitaxial films

CaRuO3 is a prototypical perovskite oxide among the Ruddlesden–Popper series with multi-exotic physical properties on the verge of quantum criticality. Unlike the case of the well-known ferromagnetic SrRuO3, the literature on the physical properties of the CaRuO3 system is scarce with no consensus about its magnetic and transport ground states. This work provides a detailed study of the magnetotransport properties of 300 nm CaRuO3 epitaxial films grown on single crystalline SrTiO3 and LaAlO3 substrates. The magnetic and electronic ground states in tensile strained CaRuO3/SrTiO3 films and compressively strained CaRuO3/LaAlO3 films are found to be distinctly different. In particular, in zero magnetic field, the high-temperature resistivity of both films show a T1/2 non-Fermi liquid behavior. Cooling below 30 K, CaRuO3/SrTiO3 undergoes metal–insulator-transition ascribed by 3D weak localization, with signs of weak ferromagnetic-like domains. By contrast, the transport data of the nonmagnetic CaRuO3/LaAlO3 film below 30 K, show T3/2 non-Fermi liquid type behavior. Magnetoresistance in CaRuO3/SrTiO3 shows combination of weak antilocalization and weak localization behaviors deep in the insulating side, emphasizing the existence of spin–orbit coupling and the strong influence of ferromagnetic impurities. Moreover, the nonlinearity signals in CaRuO3/SrTiO3 Hall measurements could be described by anomalous Hall effects. Interestingly, below 30 K, magnetoresistance and Hall in CaRuO3/LaAlO3 change sign, indicating an inversion from hole-like to electron-like behavior. We discuss the sensitivity of the 300 nm CaRuO3/SrTiO3 and CaRuO3/LaAlO3 films to the 30 K temperature, an additional quantum critical feature to the ruthenate oxides.

Evaluation of Sputtering Processes in Strontium Iridate Thin Films

The growth of epitaxial thin films from the Ruddlesden–Popper series of strontium iridates by magnetron sputtering is analyzed. It was found that, even using a non-stoichiometric target, the films formed under various conditions were consistently of the perovskite-like n = ∞ SrIrO3 phase, with no evidence of other RP series phases. A detailed inspection of the temperature–oxygen phase diagram underscored that kinetics mechanisms prevail over thermodynamics considerations. The analysis of the angular distribution of sputtered iridium and strontium species indicated clearly different spatial distribution patterns. Additionally, significant backsputtering was detected at elevated temperatures. Thus, it is assumed that the interplay between these two kinetic phenomena is at the origin of the preferential nucleation of the SrIrO3 phase. In addition, strategies for controlling cation stoichiometry off-axis have also been explored. Finally, the long-term stability of the films has been demonstrated.

Thermodynamic-driven selective synthesis and phase transformation of Sr-doped neodymium nickelate Ruddlesden–Popper epitaxial films

Recent discovery of the signature of 80 K superconductivity in La3Ni2O7 single crystals under high pressure sheds the light on the realization of high temperature superconductors from Ruddlesden–Popper nickelates. Here, we demonstrated the realization of selective fabrication of Nd0.8Sr0.2NiO3 perovskite films and (Nd0.8Sr0.2)2NiO4 Ruddlesden–Popper films from one ceramic Nd0.8Sr0.2NiO3 target simply by controlling the growth temperature. Our results further show that the as-grown Nd0.8Sr0.2NiO3 films can be transformed to (Nd0.8Sr0.2)2NiO4 by annealing in air at 1000 °C. Nd0.8Sr0.2NiO3 and (Nd0.8Sr0.2)2NiO4 films were found to be metallic and insulating, respectively. X-ray photoelectron spectroscopy results reveal that the as-grown (Nd0.8Sr0.2)2NiO4 films contained NiO impurity, which can be removed by high temperature annealing. X-ray absorption spectroscopy measurements indicate a lower Ni valence state and weakened hybridization between Ni–O in (Nd0.8Sr0.2)2NiO4 films. Substrate lattice strain strongly affects the stability of Nd0.8Sr0.2NiO3 and the formation of (Nd0.8Sr0.2)2NiO4. These results suggest an important role of thermodynamic principles in the growth and post-annealing of nickelate films. These findings provide an approach to obtain Ruddlesden–Popper series nickelate films and offer certain impetuses to the development of nickelate superconductivity.

Procedure for Estimating the Content of Planar Defects in A2BO4 Structures of the Ruddlesden–Popper Series on the Example of Sr2TiO4

Procedure for Estimating the Content of Planar Defects in A2BO4 Structures of the Ruddlesden–Popper Series on the Example of Sr2TiO4

Epitaxial growth of the first two members of the Ban+1InnO2.5n+1 Ruddlesden–Popper homologous series

We demonstrate the epitaxial growth of the first two members, and the n=∞ member of the homologous Ruddlesden–Popper series of Ban+1InnO2.5n+1 of which the n=1 member was previously unknown. The films were grown by suboxide molecular-beam epitaxy where the indium is provided by a molecular beam of indium-suboxide [In2O (g)]. To facilitate ex situ characterization of the highly hygroscopic barium indate films, a capping layer of amorphous SiO2 was deposited prior to air exposure. The structural quality of the films was assessed by x-ray diffraction, reflective high-energy electron diffraction, and scanning transmission electron microscopy.

Synthesis of Ruddlesden-Popper LaSrFe1-Cr O4 phases (x = 0.0, 0.2, 0.4, 0.6) by glycine-nitrate combustion process: Effect of Cr doping on magnetic, optical and photocatalytic properties

This work presents the study of new Ruddlesden-Popper phases, LaSrFe 1- x Cr x O 4 ( x = 0.0, 0.2, 0.4 and 0.6), synthesized by glycine-nitrate combustion method. In this research, we are for the first time reporting on a complete Ruddlesden-Popper series ( n = 1) for the photocatalytic degradation of a dye. The effect of Cr 3+ doping on the crystal structure, optical and magnetic properties of the LaSrFeO 4 phase has also been systematically explored via different characterization techniques. Rietveld refinement of PXRD data indicates the formation of single phase compounds with tetragonal symmetry in the space group I 4/ mmm . The results show a decrease in the lattice parameters a and c , as well as the unit cell volume V , with increase in Cr 3+ doping. The energy band gap ( E g ) values calculated using the DRS spectra decreases with increase in Cr concentration. The magnetic measurements revealed dominant anti-ferromagnetic (AFM) interactions in all the phases and the appearance of weak ferromagnetic (FM) interactions with Cr 3+ doping. The results are discussed by considering the increase in Fe 3+ ─O─Cr 3+ FM interaction in addition to the Fe 3+ ─O─Fe 3+ and Cr 3+ ─O─Cr 3+ AFM super-exchange interactions induced due to random distribution of Fe 3+ and Cr 3+ ions at the octahedral site. Rhodamine B, as a dye pollutant model, was used for evaluation of photocatalytic activity of the prepared phases. Enhanced photocatalytic activity was observed with the addition of Cr 3+ substitution. The results show ~99 % degradation for x = 0.6 while only ~76 % degradation is shown for x = 0.0 sample in 40 min under visible light irradiation. • New RP-type LaSrFe 1- x Cr x O 4 phases synthesized by glycine-nitrate combustion method. • E g values decreased with increase in Cr concentration. • Dominant AFM interactions in all the phases and the appearance of weak FM interactions with Cr doping. • Enhanced photocatalytic activity was observed by Cr doping.

Influence of Cr substitution on structural, optical, and magnetic properties of La2SrFe2O7: Their application as a photocatalyst for the degradation of Rhodamine B dye

A new n = 2 Ruddlesden-Popper (RP) series La2SrFe2-xCrxO7 (x = 0.0, 0.2, 0.4, 0.6 and 0.8) has been prepared via Sol-gel Pechini method, and their structural, optical, and the magnetic characterization was done. Furthermore, we are for the first-time reporting on the photo-catalytic degradation of a dye by a complete n = 2, La2SrFe2-xCrxO7 RP series. Rietveld refinement analysis confirms the formation of single-phase compounds with tetragonal crystal symmetry and I4/mmm space group. The results indicate a steady decrease in unit cell parameters and cell volume with Cr3+ doping. Dominant anti-ferromagnetic (AFM) interactions were observed in all the phases and the appearance of weak ferromagnetic (FM) interactions takes place owing to the Fe3+―O―Cr3+ FM interaction with Cr3+ doping. The χM−FC curve for x = 0.8 phase shows the magnetization reversal (MR) phenomenon and becomes zero at Tcomp ∼127 K and the value becomes negative on further decreasing the temperature. The MR phenomenon is discussed in terms of the competing Fe3+―O―Fe3+, Fe3+―O―Cr3+, and Cr3+―O―Cr3+ super-exchange interactions. Enhanced photocatalytic activity for the degradation of Rhodamine B (RhB) dye was obtained for x = 0.2 substituted phase, displaying a ∼99% degradation of dye in 30 min followed by ∼83%, ∼75%, ∼64% and ∼61% by x = 0.4, 0.0, 0.8 and 0.6 phases respectively in the same time interval. The results are explained in terms of crystallite size, the narrowing of band gap with Cr3+ substitution, and based on of recombination of charge carriers which, are in good agreement with the results of Photoluminescence (PL) emission intensity spectra.

Sr2IrO4/Sr3Ir2O7 superlattice for a model two-dimensional quantum Heisenberg antiferromagnet

Spin-orbit entangled pseudospins hold promise for a wide array of exotic magnetism ranging from a Heisenberg antiferromagnet to a Kitaev spin liquid depending on the lattice and bonding geometry, but many of the host materials suffer from lattice distortions and deviate from idealized models in part due to inherent strong pseudospin-lattice coupling. Here, we report on the synthesis of a magnetic superlattice comprising the single ($n$=1) and the double ($n$=2) layer members of the Ruddlesden-Popper series iridates Sr$_{n+1}$Ir$_{n}$O$_{3n+1}$ alternating along the $c$-axis, and provide a comprehensive study of its lattice and magnetic structures using scanning transmission electron microscopy, resonant elastic and inelastic x-ray scattering, third harmonic generation measurements and Raman spectroscopy. The superlattice is free of the structural distortions reported for the parent phases and has a higher point group symmetry, while preserving the magnetic orders and pseudospin dynamics inherited from the parent phases, featuring two magnetic transitions with two symmetry-distinct orders. We infer weaker pseudospin-lattice coupling from the analysis of Raman spectra and attribute it to frustrated magnetic-elastic couplings. Thus, the superlattice expresses a near ideal network of effective spin-one-half moments on a square lattice.

Electronic structure of higher-order Ruddlesden-Popper nickelates

We analyze the electronic structure of the recently synthesized higher-order nickelate Ruddlesden-Popper phases ${\mathrm{La}}_{n+1}{\mathrm{Ni}}_{n}{\mathrm{O}}_{3n+1}$ $(n=4--6)$ using first-principles calculations. For all materials, our results show large holelike Fermi surfaces with ${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ character that closely resemble those of optimally hole-doped cuprates. For higher values of $n$, extra non-cuprate-like bands of ${d}_{{z}^{2}}$ orbital character appear. These aspects highlight that this Ruddlesden-Popper series can provide a means to modify the electronic ground states of nickelates by tuning their dimensionality. With their similarities and differences to the cuprates, this new family of materials can potentially shed light on the physics of copper-based oxides.

Effect of M site cation ordering on the lattice dynamical properties of the tetragonal Sr2MO4 (M=Cr, Fe, Co, Mo, and Sn) crystals

ABSTRACT Using normal coordinate analysis, the Raman and Infrared phonons are investigated for the tetragonal Ruddlesden-Popper series in phase I4/mmm and symmetry D4h 17. Three stretching and six bending force constants have been included for the calculations of the zone centre vibrational modes. Theoretical assignments for the Raman and infrared wavenumbers for Sr2CrO4, Sr2MoO4, and Sr2SnO4 compounds have been reported for the first time. As per our knowledge, no theoretical assignment has been done for the infrared frequencies for Sr2FeO4 and Sr2CoO4 compounds in I4/mmm phase so far. A strong correlation of the M site has been observed for the various frequencies giving insight into the structure of the studied compounds. The force constants involving the M-site atom show an expected set trend and also indicate the changes in values whenever the atomic orbit changes. Also, the frequencies which are completely dominated by the M atoms show a specific nature as the atomic number changes indicating the strong effect of the size of the M atom in the vibrational properties. In the tetragonal structure of the Ruddlesden-Popper phase of Sr2MO4 (M=Cr, Fe, Co, Mo, and Sn) crystals for each normal mode, the potential energy distributions have been analysed and the contributions of bending and stretching force constants towards different frequencies have been determined.

Determination of the Oxygen Content of Perovskite Oxides Belonging to the RUDDLESDEN-POPPER (RP) Series and Studying of Conductivity and Electrical Resistance

Determination of the Oxygen Content of Perovskite Oxides Belonging to the RUDDLESDEN-POPPER (RP) Series and Studying of Conductivity and Electrical Resistance

Phase transition at ambient pressure in complex oxide Sr3ScCoO6+δ. Morphotropic row Sr3ScMO7-δ (M = Ni–Cr)

A phase transition from a quasi-one-dimensional hexagonal structure (1D) to a two-dimensional layered structure (2D) of the second homolog of the Ruddlesden-Popper series was detected in the Sr3ScCoO6+δ complex oxide. The transition is unique since it occurs when the temperature increases without the use of high pressures and changes in the oxygen partial pressure. Using high-temperature X-ray diffraction and differential scanning calorimetry in situ, a transition temperature range 1296 ​K–1433 ​K was established. It is shown that in the quasi-one-dimensional phase the scandium and cobalt cations are ordered by prismatic and octahedral positions, while in the two-dimensional perovskite-like oxide they are statistically distributed by octahedral positions. Sr3ScCoO6+δ is the only compound in the Sr3ScMO7-δ (M ​= ​Ni - Cr) morphotropic series, which exists in two structural types. The 1D → 2D transformation is associated with the ability of cobalt to be in various combinations of oxidation states and spin states. The temperature dependence of the magnetic susceptibility of oxides of both types of structure in the Sr3ScMO7-δ (M ​= ​Ni - Cr) series is paramagnetic due to magnetic dilution with Sc ion. The tetragonal modification of Sr3ScCoO6+δ has a significantly larger magnetic moment compared to the hexagonal one.

Negative thermal expansion in the Ruddlesden-Popper calcium titanates

Materials exhibiting negative thermal expansion (NTE) are important for the fabrication and operation of microelectronic devices and optical systems. As an important group of Ruddlesden-Popper (RP) perovskites, calcium titanates ${\mathrm{Ca}}_{n+1}{\mathrm{Ti}}_{n}{\mathrm{O}}_{3n+1}$ [(CTO), $n=1,2,...,\ensuremath{\infty}$] have layered structures and may exhibit quasi-two-dimensional (quasi-2D) NTE within their three-dimensional structural architectures. In this paper, combining density-functional-theory calculations and the self-consistent quasiharmonic approximation method, we investigate the variation of the quasi-2D character of the phonon spectra and thermal expansion in the ${\mathrm{Ca}}_{n+1}{\mathrm{Ti}}_{n}{\mathrm{O}}_{3n+1}$ family ($n=1--3$, and $\ensuremath{\infty}$) with respect to $n$. We find that a quasi-2D NTE mechanism is active in the RP-CTOs at $n$ of 1--3, whereas a quasi-rigid-unit mode mechanism is active at $n=\ensuremath{\infty}$ (i.e., the perovskite phase). We find a NTE trend with layer number for the orthorhombic materials comprising the RP series, but the monoclinic polymorph is an outlier. For the orthorhombic members, we find the critical pressure for NTE increases with increasing $n$, but the NTE critical temperature decreases (when materials are compared at the same pressure). Additionally, the elastic moduli can be used as effective descriptors for this layer-dependent behavior of the NTE, i.e., the stiffer the RP-CTO then the lower its NTE. We also propose the integrated NTE capacity to capture the correlation between the quasi-2D NTE and $n$, and it monotonically decreases with increasing $n$.

Advanced First-Principle Modeling of Relativistic Ruddlesden—Popper Strontium Iridates

In this review, we provide a survey of the application of advanced first-principle methods on the theoretical modeling and understanding of novel electronic, optical, and magnetic properties of the spin-orbit coupled Ruddlesden–Popper series of iridates Srn+1IrnO3n+1 (n = 1, 2, and ∞). After a brief description of the basic aspects of the adopted methods (noncollinear local spin density approximation plus an on-site Coulomb interaction (LSDA+U), constrained random phase approximation (cRPA), GW, and Bethe–Salpeter equation (BSE)), we present and discuss select results. We show that a detailed phase diagrams of the metal–insulator transition and magnetic phase transition can be constructed by inspecting the evolution of electronic and magnetic properties as a function of Hubbard U, spin–orbit coupling (SOC) strength, and dimensionality n, which provide clear evidence for the crucial role played by SOC and U in establishing a relativistic (Dirac) Mott–Hubbard insulating state in Sr2IrO4 and Sr3Ir2O7. To characterize the ground-state phases, we quantify the most relevant energy scales fully ab initio—crystal field energy, Hubbard U, and SOC constant of three compounds—and discuss the quasiparticle band structures in detail by comparing GW and LSDA+U data. We examine the different magnetic ground states of structurally similar n = 1 and n = 2 compounds and clarify that the origin of the in-plane canted antiferromagnetic (AFM) state of Sr2IrO4 arises from competition between isotropic exchange and Dzyaloshinskii–Moriya (DM) interactions whereas the collinear AFM state of Sr3Ir2O7 is due to strong interlayer magnetic coupling. Finally, we report the dimensionality controlled metal–insulator transition across the series by computing their optical transitions and conductivity spectra at the GW+BSE level from the the quasi two-dimensional insulating n = 1 and 2 phases to the three-dimensional metallic n=∞ phase.

Phase equilibria and oxygen content of intermediate phases in the Sm2O3–SrO–Fe2O3 system

Six types of oxide phases are formed in the Sm2O3–SrO–Fe2O3 system at 1100 °C in air: perovskite type Sr1-хSmхFeO3-δ (0.05 ≤ х ≤ 0.50 with the cubic structure, S.G. Pm-3m and 0.85 ≤ x ≤ 1.0 with the orthorhombic structure, S.G. Pbnm), and Ruddlesden-Popper series corresponding to n = 1,2,3, i.e. Sr2-ySmyFeO4-δ, Sr3-uSmuFe2O7-δ (0 ≤ u ≤ 0.3; u = 1.80) and Sr4-rSmrFe3O10-δ. The structural parameters of single-phase samples, refined by the Rietveld method, allowed to reveal the variation of unit cell parameters with composition. A subsolidus isothermal isobaric phase diagram (1100 °C, Po2 = 0.21 atm) for the ½Sm2O3–SrO–½Fe2O3 system has been constructed. The compositional triangle was divided into 24 phase fields. The values of oxygen content and mean oxidation state of iron in all single phases were determined by iodometric titration. The changes in oxygen content with temperature in Sr2.7Sm0.3Fe2O7-δ, Sr1.2Sm0.8FeO4-δ, and Sr3.1Sm0.9Fe3O10-δ were studied by TGA within the range of 25−1100 °C in air. They show that the maximum oxidation state of Fe ions in RP oxides at room temperature increases with n, reaching 3.52 for the Sr3.1Sm0.9Fe3O10-δn = 3 member.

Activating ORR and OER in Ruddlesden-Popper based catalysts by enhancing interstitial oxygen and lattice oxygen redox reactions

Numerous theoretical and experimental works about Ruddlesden-Popper (RP) based oxygen catalysts were based on the critical assumption: oxygen vacancies do exist in the perovskite-like layer, and which with the interstitial O2− (in rock-salt (AO) layers) were the two key influencing factors to determine RP’ oxygen exchange rate and oxygen catalytic ability. But overall, the presence or absence of critical oxygen vacancies in the perovskite-like layer of RP oxides is still unclear. Here, from our experimental results, no oxygen vacancy was detected in the perovskite-like layer of RP series materials. Herein, for the Ruddlesden-Popper based oxygen catalysts, we proposed that more interstitial O2− in the AO layers and high-active lattice oxygen ions in the perovskite-like layers are the determinant factors to activate the ORR and OER. Accordingly, we reveal that the high-valence ion doping strategy for RP electrode can enhances the redox reactions while improving the lattice-oxygen activity and interstitial O2− concentration, and then benefiting the ORR and OER activity.

(Invited) Ruddlesden-Popper-Type Oxides As Air Electrodes for Solid Oxide Electrolyzer Cells

Ruddlesden-Popper-type oxides are promising air electrode materials for solid oxide fuel cells (SOFCs) and electrolyser cells (SOECs). Within the Ruddlesden-Popper (RP) series Lnn+1BnO3n+1, first order (n=1) RP-type rare earth nickelates with Ln=La, Nd, Pr and B=Ni show high oxygen diffusivities, high catalytic activity for the oxygen reduction reaction as well as good electronic and ionic conductivities [1]. In order to further improve the surface oxygen exchange kinetics, the effect of partial substitution of Ni by Co on the B-site in Pr2NiO4+δ was studied, similar to an earlier report for the La2NiO4+δ system [2].Structure-composition-property–relationships were examined for the Pr2NiO4+δ system. The effect of A-site substitution of Pr with La as well as B-site substitution of Ni with Cobalt was investigated with respect to crystal structure, thermodynamic stability, oxygen non-stoichiometry, electronic conductivity as well as oxygen surface exchange and transport properties. Moreover, differences in functional properties between Ruddlesden-Popper phases of different order within the same compositional system were studied. In cases where material characterisation was problematic due to difficulties in obtaining densely sintered samples with high phase purity (including of third-order RP-Phases), electrochemical impedance spectroscopy (EIS) measurements on microelectrodes were applied in order to obtain reliable results for oxygen surface exchange rates. Oxygen surface exchange coefficients kq and kδ could be calculated from surface resistances and chemical capacitances of the thin-film electrodes between 550 and 850°C. Substitution of Ni by 10% of Co in Pr2NiO4+δ results in increased oxygen surface exchange rates expecially at lower oxygen partial pressures [3]. Performance tests with Pr2Ni0.9Co0.1O4+δ SOEC air electrodes for water electrolysis were conducted on anode supported full cells at 800°C at OCV conditions and in electrolyser mode up to current densities of 1000 mA cm-2. For anode supported cells, an electrode-electrolyte composite was used as functional anode layer in order to improve adhesion and avoid delamination issues. Moreover, the long-term stability and resistance against Cr-poisoning was examined by electrochemical impedance spectroscopy and current-voltage measurements on symmetrical cells at 800°C in dry and humid atmospheres. A three-electrode configuration allowed to analyse the time dependence of the air electrode polarization resistance during the SOFC as well as SOEC operation mode. Compared to La2NiO4+δ, a reduced susceptibility for Cr-poisoning was found for Pr2Ni0.9Co0.1O4+δ over a period of 1000 hours in SOEC operation.The development of high-performance SOEC air electrodes is part of the Austrian integrated project HydroMetha. This project combines high-temperature co-electrolysis of CO2 and H2O by solid oxide cells with catalytic methanation in order to enable storage of electrical energy from fluctuating renewable sources with high overall efficiency.

3D-Ising like ferromagnetism in skyrmionic-bubbles host infinite-layer La0.825Sr0.175MnO3 manganite perovskite

The critical behavior of infinite-layer La0.825Sr0.175MnO3 of Ruddlesden–Popper series manganite has been studied around the transition temperature (). To reveal the universality class that explains the critical behavior in La0.825Sr0.175MnO3 several methods, such as modified Arrott plots, Kouvel–Fisher, entropy and critical isotherm analysis have been employed. The critical exponent for infinite-layer is obtained independently from critical magnetization isotherm and found to satisfy the Widom scaling relation . The universality class of the critical phenomenon in infinite-layer La0.825Sr0.175MnO3 manganite can be explained with the help of renormalization group theory approach for three dimensional (3D) systems. We have shown that a short-range 3D-Ising type interaction is responsible for ferromagnetic and second-order phase transition to paramagnetic phase.