Hole‐doped high entropy ferrites: Structure and charge compensation mechanisms in (Gd 0.2 La 0.2 Nd 0.2 Sm 0.2 Y 0.2 ) 1− x Ca x FeO 3

High entropy oxides (HEOs) can be defined as single-phase oxide solid solutions with five or more cations in near equiatomic proportion occupying a given cation sub-lattice. The compositional flexibility while retaining the phase purity can be considered one of the major strengths of this materials class. Taking advantage of this aspect, here we explore the extent to which an aliovalent hole dopant can be incorporated into a perovskite-HEO system. Nine systems, (Gd0.2La0.2Nd0.2Sm0.2Y0.2)1−xCaxFeO3, with varying amount of Ca content (x = 0–.5) are synthesized using nebulized spray pyrolysis. Single-phase orthorhombic (Pbnm) structure can be retained up to 20% of Ca doping. Beyond 20% of Ca, a secondary rhombohedral (R-3c) phase emerges. The 57Fe Mössbauer spectra indicate that charge compensation occurs only via oxygen vacancy formation in the single-phase systems containing up to 15% of Ca. In addition, partial transition from Fe3+ to Fe4+ occurs in the 20% Ca-doped case. Room temperature Mössbauer spectroscopy further reflects the coexistence of multiple magnetic phases in crystallographic single-phase (Gd0.2La0.2Nd0.2Sm0.2Y0.2)1−xCaxFeO3, which is supported by magnetometry measurements. These initial results show the potential of charge doping to tune structural–magneto–electronic properties in compositionally complex HEOs, warranting further research in this direction

Overview of the 3rd International Competition on Plagiarism Detection

[EN] This paper overviews eleven plagiarism detectors that have been developed and evaluated within PAN’11. We survey the detection approaches developed for the two sub-tasks “external plagiarism detection” and “intrinsic plagiarism detection,” and we report on their detailed evaluation based on the third revised edition of the PAN plagiarism corpus PAN-PC-11.This work was partly funded by the European Commission as part of the WIQEI IRSES project (grant no. 269180) within the FP7 Marie Curie People Framework, by MICINN as part of the TextEnterprise 2.0 project (TIN2009-13391-C04-03) within the Plan I+D+i, and as part of the VLC/CAMPUS Microcluster on Multimodal Interaction in Intelligent Systems.Potthast, M.; Eiselt, A.; Barrón Cedeño, LA.; Stein, B.; Rosso, P. (2011). Overview of the 3rd International Competition on Plagiarism Detection. CEUR Workshop Proceedings. 1177. http://hdl.handle.net/10251/46639S117

High Entropy Approach to Engineer Strongly Correlated Functionalities in Manganites

Technologically relevant strongly correlated phenomena such as colossal magnetoresistance (CMR) and metal-insulator transitions (MIT) exhibited by perovskite manganites are driven and enhanced by the coexistence of multiple competing magneto-electronic phases. Such magneto-electronic inhomogeneity is governed by the intrinsic lattice-charge-spin-orbital correlations, which, in turn, are conventionally tailored in manganites via chemical substitution, charge doping, or strain engineering. Alternately, the recently discovered high entropy oxides (HEOs), owing to the presence of multiple-principal cations on a given sub-lattice, exhibit indications of an inherent magneto-electronic phase separation encapsulated in a single crystallographic phase. Here, the high entropy (HE) concept is combined with standard property control by hole doping in a series of single-phase orthorhombic HE-manganites (HE-Mn), (Gd$_{0.25}$La$_{0.25}$Nd$_{0.25}$Sm$_{0.25}$)$_{1-x}$Sr$_x$MnO$_3$ (x = 0–0.5). High-resolution transmission microscopy reveals hitherto-unknown lattice imperfections in HEOs: twins, stacking faults, and missing planes. Magnetometry and electrical measurements infer three distinct ground states—insulating antiferromagnetic, unpercolated metallic ferromagnetic, and long-range metallic ferromagnetic—coexisting or/and competing as a result of hole doping and multi-cation complexity. Consequently, CMR ≈1550% stemming from an MIT is observed in polycrystalline pellets, matching the best-known values for bulk conventional manganites. Hence, this initial case study highlights the potential for a synergetic development of strongly correlated oxides offered by the high entropy design approach

Neighbourhood Reduction in Global and Combinatorial Optimization: The Case of the p-Centre Problem

Neighbourhood reductions for a class of location problems known as the vertex (or discrete) and planar (or continuous) p-centre problems are presented. A brief review of these two forms of the p-centre problem is first provided followed by those respective reduction schemes that have shown to be promising. These reduction schemes have the power of transforming optimal or near optimal methods such as metaheuristics or relaxation-based procedures, which were considered relatively slow, into efficient and exciting ones that are now able to find optimal solutions or tight lower/upper bounds for larger instances. Research highlights of neighbourhood reduction for global and combinatorial optimisation problems in general and for related location problems in particular are also given

Hole‐doped high entropy ferrites: Structure and charge compensation mechanisms in (Gd₀.₂La₀.₂Nd₀.₂Sm₀.₂Y₀.₂)₁₋ₓCaₓFeO₃

High entropy oxides (HEOs) can be defined as single‐phase oxide solid solutions with five or more cations in near equiatomic proportion occupying a given cation sub‐lattice. The compositional flexibility while retaining the phase purity can be considered one of the major strengths of this materials class. Taking advantage of this aspect, here we explore the extent to which an aliovalent hole dopant can be incorporated into a perovskite‐HEO system. Nine systems, (Gd₀.₂La₀.₂Nd₀.₂Sm₀.₂Y₀.₂)₁₋ₓCaₓFeO₃, with varying amount of Ca content (x = 0–.5) are synthesized using nebulized spray pyrolysis. Single‐phase orthorhombic (Pbnm) structure can be retained up to 20% of Ca doping. Beyond 20% of Ca, a secondary rhombohedral (R‐3c) phase emerges. The ⁵⁷Fe Mössbauer spectra indicate that charge compensation occurs only via oxygen vacancy formation in the single‐phase systems containing up to 15% of Ca. In addition, partial transition from Fe³⁺ to Fe⁴⁺ occurs in the 20% Ca‐doped case. Room temperature Mössbauer spectroscopy further reflects the coexistence of multiple magnetic phases in crystallographic single‐phase (Gd₀.₂La₀.₂Nd₀.₂Sm₀.₂Y₀.₂)₁₋ₓCaₓFeO₃, which is supported by magnetometry measurements. These initial results show the potential of charge doping to tune structural–magneto–electronic properties in compositionally complex HEOs, warranting further research in this direction