Crystal growth, structural phase transitions and optical gap evolution of FAPb(BrCl) hybrid perovskites (FA: formamidinium ion, CH(NH)).

Chemically tuned organic-inorganic hybrid halide perovskites based on bromide and chloride anions CH(NH)Pb(BrCl) (CH(NH): formamidinium ion, FA) have been crystallized and investigated by neutron powder diffraction (NPD), single crystal X-ray diffraction (SCXRD), scanning electron microscopy (SEM) and UV-vis spectroscopy. FAPbBr and FAPbCl experience successive phase transitions upon cooling, lowering the symmetry from cubic to orthorhombic phases; however, these transitions are not observed for the mixed halide phases, probably due to compositional disorder. The band-gap engineering brought about by the chemical doping of FAPb (BrCl) perovskites (x = 0.

New insights into the magnetism and magnetic structure of LuCrO perovskite.

A polycrystalline sample LuCrO has been characterized by neutron powder diffraction (NPD) and magnetization measurements. Its crystal structure has been Rietveld refined from NPD data in space group Pnma; this perovskite contains strongly tilted CrO octahedra with extremely bent Cr-O-Cr superexchange angles of ∼142°. The NPD data show that below Néel temperature (T ≃ 131 K), the magnetic structure can be defined as an A-type antiferromagnetic arrangement of Cr magnetic moments, aligned along the b axis, with a canting along the c axis.

Magnetoelectric effect in multiferroic nickelate perovskite YNiO.

The interaction of magnetic order and spontaneous polarization is a fundamental coupling with the prospect for the control of electronic properties and magnetism. The connection among magnetic order, charge localization and associated metal-insulator transition (MIT) are cornerstones for materials control. Materials that combine both effects are therefore of great interest for testing models that claim the occurrence of spontaneous polarization from magnetic and charge order.

Unveiling the Structural Properties, Optical Behavior, and Thermoelectric Performance of 2D CsSnBr Halide Obtained by Mechanochemistry.

Metal halide perovskites with a two-dimensional structure are utilized in photovoltaics and optoelectronics. High-crystallinity CsSnBr specimens have been synthesized via ball milling. Differential scanning calorimetry curves show melting at 553 K (endothermic) and recrystallization at 516 K (exothermic).

Optimizing Thermoelectric Properties through Compositional Engineering in Ag-Deficient AgSbTe Synthesized by Arc Melting.

Thermoelectric materials offer a promising avenue for energy management, directly converting heat into electrical energy. Among them, AgSbTe has gained significant attention and continues to be a subject of research at further improving its thermoelectric performance and expanding its practical applications. This study focuses on Ag-deficient AgSbTe and AgSbTeSe materials, examining the impact of compositional engineering within the AgSbTe thermoelectric system.

Multiscale Length Structural Investigation and Thermoelectric Performance of Double-Filled SrYbCoSb: An Exceptional Thermal Conductivity Reduction by Filler Segregation to the Grain Boundaries.

Among thermoelectric materials, skutterudites are the most prominent candidates in the mid-temperature range applications. In the multiple-filled SrYbCoSb skutterudite, with Sr and Yb as fillers, we have enhanced the thermoelectric performance of CoSb through the reduction of lattice thermal conductivity and the optimization of carrier concentration and electrical conductivity. The high-pressure synthesis of the double-filled derivative promotes filling fraction fluctuation.

Exotic Magnetism in Perovskite KOsO_{3}.

A new perovskite KOsO_{3} has been stabilized under high-pressure and high-temperature conditions. It is cubic at 500 K (Pm-3m) and undergoes subsequent phase transitions to tetragonal at 320 K (P4/mmm) and rhombohedral (R-3m) at 230 K as shown from refining synchrotron x-ray powder diffraction (SXRD) data. The larger orbital overlap integral and the extended wave function of 5d electrons in the perovskite KOsO_{3} allow to explore physics from the regime where Mott and Hund's rule couplings dominate to the state where the multiple interactions are on equal footing.

SrMoO Perovskite with Segregated Ru Nanoparticles Performing as Anode in Solid Oxide Fuel Cells.

A new anode material, Ru-SrMoO, with a perovskite structure and segregated metallic Ru, has been tested in an intermediate-temperature solid oxide fuel cell (IT-SOFC) in an electrolyte-supported configuration giving substantial power densities as high as 840 mW/cm at 850 °C using pure H as fuel. This material has been prepared by the citrate method and structurally and microstructurally characterized at room temperature by different techniques such as X-ray diffraction (XRD), neutron powder diffraction (NPD), scanning electron microscopy (SEM), and scanning transmission electron microscopy (STEM). NPD was very useful to determine oxygen positions and vacancies, unveiling a cubic and oxygen-deficient perovskite SrMoO oxide with a 3 space group and potential ionic mobility.

Magnetoelastic Coupling Evidence by Anisotropic Crossed Thermal Expansion in Magnetocaloric RSrCoFeO (R = Sm, Eu) Double Perovskites.

Double perovskite oxides, characterized by their tunable magnetic properties and robust interconnection between the lattice and magnetic degrees of freedom, present an enticing foundation for advanced magnetic refrigeration materials. Herein, we delve into the influence of rare-earth elements on RSrCoFeO (R = Sm, Eu) disordered double perovskites by examining their structural, electronic, magnetic, and magnetocaloric properties. Temperature-dependent synchrotron X-ray diffraction analysis confirmed the stability of the orthorhombic phase () across a wide temperature range.

Structural and Electrical Characterization of LaSrAlMgO Layered Perovskites Obtained by Mechanical Synthesis.

This work presents the structural and electrical characterization of KNiF-type layered perovskites of LaSrAlMgO composition to be used as oxide-ion electrolytes for a solid-oxide fuel cell (SOFC). These perovskites were prepared by mechano-chemical synthesis (ball milling), an alternative to traditional synthesis methods such as citrate-nitrates and solid-state reaction. With these methods, two things are avoided: first, the use of nitrate salts, which are more environmentally harmful than oxide precursors, and second, it saves the series of long thermal treatments associated with solid-state reactions.

Elucidating the Magnetoelastic Coupling, Pressure-Dependent Magnetic Behavior, and Anomalous Hall Effect in FeTiS Intercalation Sulfides.

Transition-metal chalcogenides with intercalated layered structures are interesting systems in material physics due to their attractive electronic and magnetic properties, with applications in the fields of magnetic refrigerators, catalysts, and thermoelectrics, among others. In this work, we studied in detail the structural, electronic, and magnetic properties of (Fe,Ti)-based sulfides with formula FeTiS ( = 0.24, 0.

Structural Features and Optical Properties of All-Inorganic Zero-Dimensional Halides CsPbBrI Obtained by Mechanochemistry.

Despite the great success of hybrid CHNHPbI perovskite in photovoltaics, ascribed to its excellent optical absorption properties, its instability toward moisture is still an insurmountable drawback. All-inorganic perovskites are much less sensitive to humidity and have potential interest for solar cell applications. Alternative strategies have been developed to design novel materials with appealing properties, which include different topologies for the octahedral arrangements from three-dimensional (3D, e.

Active and durable RMnRuO pyrochlores with low Ru content for acidic oxygen evolution.

The production of green hydrogen in water electrolyzers is limited by the oxygen evolution reaction (OER). State-of-the-art electrocatalysts are based on Ir. Ru electrocatalysts are a suitable alternative provided their performance is improved.

Thermal Expansion and Rattling Behavior of Gd-Filled CoSb Skutterudite Determined by High-Resolution Synchrotron X-ray Diffraction.

In this work, Gd-filled skutterudite GdxCo4Sb12 was prepared using one step method under high pressure in a piston-cylinder-based press at 3.5 GPa and moderate temperature of 800 °C. A detailed structural characterization was performed using synchrotron X-ray diffraction (SXRD), revealing a filling fraction of x = 0.

Highly active and stable OER electrocatalysts derived from SrMIrO for proton exchange membrane water electrolyzers.

Proton exchange membrane water electrolysis is a promising technology to produce green hydrogen from renewables, as it can efficiently achieve high current densities. Lowering iridium amount in oxygen evolution reaction electrocatalysts is critical for achieving cost-effective production of green hydrogen. In this work, we develop catalysts from Ir double perovskites.

Reduced Thermal Conductivity in Nanostructured AgSbTe Thermoelectric Material, Obtained by Arc-Melting.

AgSbTe intermetallic compound is a promising thermoelectric material. It has also been described as necessary to obtain LAST and TAGS alloys, some of the best performing thermoelectrics of the last decades. Due to the random location of Ag and Sb atoms in the crystal structure, the electronic structure is highly influenced by the atomic ordering of these atoms and makes the accurate determination of the Ag/Sb occupancy of paramount importance.

Crystal structure thermal evolution and novel orthorhombic phase of methylammonium lead bromide, CHNHPbBr.

Methylammonium (MA) lead trihalide perovskites, CHNHPbX (X = I, Br, Cl), have emerged as a new class of light-absorbing materials for photovoltaic applications, reaching efficiencies of 23% when implemented in solar cell heterojunctions. In particular, MAPbBr is a promising member with a large bandgap that gives rise to a high open circuit voltage. Here we present a structural study from neutron diffraction (ND) data of an undeuterated MAPbBr specimen, carried out to follow its crystallographic behaviour in the 2-298 K temperature range.

Highly Active and Stable Ni/La-Doped Ceria Material for Catalytic CO Reduction by Reverse Water-Gas Shift Reaction.

The design of an active, effective, and economically viable catalyst for CO conversion into value-added products is crucial in the fight against global warming and energy demand. We have developed very efficient catalysts for reverse water-gas shift (rWGS) reaction. Specific conditions of the synthesis by combustion allow the obtention of macroporous materials based on nanosized Ni particles supported on a mixed oxide of high purity and crystallinity.

Al-Doped SrMoO Perovskites as Promising Anode Materials in Solid Oxide Fuel Cells.

Two perovskite materials with SrMoAlO (x = 0.1, 0.2) compositions have been synthesized by reduction from the corresponding scheelite phases, with SrMoAlO stoichiometry; the pertinent characterization shows that the defective perovskites can be used as anode materials in solid oxide fuel cells, providing maximum output power densities of 633 mW/cm for x = 0.

Nitridation effect on lithium iron phosphate cathode for rechargeable batteries.

A novel oxynitride LiFePON with olivine structure (space group , no. 62) has been synthesized by heating a parent LiFePO precursor obtained by citrate chemistry in flowing ammonia at 650 °C. The polycrystalline sample has been characterized by X-ray and neutron powder diffraction (NPD), elemental and thermal analysis, scanning electron microscopy (SEM) and electrochemical measurements.

Synthesis conditions impact on SrMoO electroceramic: crystal structure, stability and transport properties.

Crystal structure and properties of SrMoO treated at 1100 and 1400 °C were studied synchrotron X-ray powder diffraction and thermogravimetric analysis, coupled with mass spectrometry. Synchrotron studies reveal the crystallographic effect of the annealing temperature, showing that the lowest-temperature phase must be defined in a triclinic symmetry, in contrast to the cubic one obtained at 1400 °C. The mass spectrometry allowed the identification of the released compounds during the thermogravimetric analysis, thus unveiling the physicochemical behavior of the sample during the heating process.

Detailed Structural Features of the Perovskite-Related Halide RbPbI for Solar Cell Applications.

All-inorganic lead halide perovskites like CsPbBr, CsPbI, or RbPbI are good replacements for the classical hybrid organic-inorganic perovskites like CHNHPbI, susceptible to fast degradation in the presence of humid air. They also exhibit outstanding light absorption properties suitable for solar energy applications. Here, we describe the synthesis of RbPbI by mechanochemical procedures with green credentials, avoiding toxic or expensive organic solvents; this specimen exhibits excellent crystallinity.

On the magnetic structure and magnetic behaviour of the most distorted member of the series of RNiO perovskites (R = Lu).

The crystal structure of LuNiO perovskite has been examined below RT and across = 125 K by neutron powder diffraction. In this temperature region (2-298 K), well below the metal-insulator transition this oxide exhibits at = 599 K, this material is insulating and characterized by a partial charge disproportionation of the Ni valence. In the perovskite structure, defined in the monoclinic 2/ space group, there are two inequivalent Ni sites located in alternating octahedra of different sizes.