Search

Three new double corundum derived compounds, Fe3-xInSnxO6, (x = 0. 0.25, 0.5) were synthesized at high pressure and temperature (6 GPa, 1400-1450 C) All the compounds order antiferromagnetically well above room temperature, TN = 608 K, 532K, and 432 K for x = 0, 0.25, 0.5, respectively. The x = 0 phase crystalizes as centrosymmetric R3c, but increasing the substitution of closed-shell d10 Sn4+ induces x = 0.25 and 0.5 to crystallize as noncentrosymmetric R3c. Microprobe measurements indicate that for x = 0.25, 0.5, the substitution of Sn4+ is not compensated for by vacancies, which implies the presence of Fe2+, as corroborated by X-ray absorption near edge spectroscopy and single crystal X-ray structure refinements. Neutron powder diffraction experiments on x = 0.5 indicate that, these compounds are canted A-type antiferromagnets which, like Fe2O3 and InFeO3, consist of ferromagnetic layers that stack antiferromagnetically with a single magnetic transition. Weak ferromagnetic interactions persist to very high temperatures. Temperature dependent second harmonic generation measurements on x = 0.25 and 0.5 show SHG response with ferroelectric-like hysteretic maxima that correspond with the respective magnetic transitions, which suggest coupling of the magnetic and polarization order. These new compounds provide more information on fine-tuning the electronic, magnetic and structural properties of corundum derived mutlferroics in the search for tunable high temperature magnetoelectric materials.

High-pressure heaters in large volume presses must reconcile potentially contradictory properties, and the whole high-pressure and high-temperature (HPHT) community has been engaged for years to seek a better heater. LaCrO

X-type hexaferrites have been receiving considerable attention due to their promising applications in many magnetic-electronic fields. However, the growth of single-crystal X-type hexaferrite is st...

Understanding the electric dipole switching in multiferroic materials requires deep insight of the atomic-scale local structure evolution to reveal the ferroelectric mechanism, which remains unclear and lacks a solid experimental indicator in high-pressure prepared LiNbO3-type polar magnets. Here, we report the discovery of Zn-ion splitting in LiNbO3-type Zn2FeNbO6 established by multiple diffraction techniques. The coexistence of a high-temperature paraelectric-like phase in the polar Zn2FeNbO6 lattice motivated us to revisit other high-pressure prepared LiNbO3-type A2BB'O6 compounds. The A-site atomic splitting (∼1.0-1.2 A between the split-atom pair) in B/B'-mixed Zn2FeTaO6 and O/N-mixed ZnTaO2N is verified by both powder X-ray diffraction structural refinements and high angle annular dark field scanning transmission electron microscopy images, but is absent in single-B-site ZnSnO3. Theoretical calculations are in good agreement with experimental results and suggest that this kind of A-site splitting also exists in the B-site mixed Mn-analogues, Mn2FeMO6 (M = Nb, Ta) and anion-mixed MnTaO2N, where the smaller A-site splitting (∼0.2 A atomic displacement) is attributed to magnetic interactions and bonding between A and B cations. These findings reveal universal A-site splitting in LiNbO3-type structures with mixed multivalent B/B', or anionic sites, and the splitting-atomic displacement can be strongly suppressed by magnetic interactions and/or hybridization of valence bands between d electrons of the A- and B-site cations.

LiNbO3 (LN)-type polar magnets are technologically important but require stringent and costly high-pressure synthesis with very limited sample yields. We develop a chemical strategy to reduce the physical synthesis pressure. LN-type polar magnets require 7 GPa to stabilize in the high-pressure Mn2FeNbO6 (MFNO) phase. Here, MFNO was successfully stabilized in the isostructural LN matrix at intermediate physical pressure (below 5 GPa) at gram levels for each run by dilution with LN according to (Li1–xMnx)(Fex/2Nb1–x/2)O3 (x = 0.18, 0.33, 0.46, 0.57). LN-diluted MFNO demonstrates ferromagnetism above room-temperature (magnetic ordering temperature TC ≈ 516–554 K) and has large estimated spontaneous polarization (PS ≈ 18–63 μC/cm2). Irreversible c-axis near-zero thermal expansion stemming from magnetostriction was observed around the magnetic transition temperature region upon heating at ambient pressure, which irreversibly elongates the distance between the face-sharing (Li/Mn) and (Fe/Nb) octahedral centroi...

Exotic perovskites significantly enrich materials for multiferroic and magnetoelectric applications. However, their design and synthesis is a challenge due to the mostly required recipe conditions at extremely high pressure. Herein, we presented the Ca2−xMnxMnTaO6 (0 ≤ x ≤ 1.0) solid solutions stabilized by chemical pressure assisted with intermediate physical pressure up to 7 GPa. The incorporation of Mn2+ into the A-site neither drives any cationic ordering nor modifies the orthorhombic Pbnm structure, namely written as (Ca1−x/2Mnx/2)(Mn1/2Ta1/2)O3 with disordered A and B site cationic arrangements. The increment of x is accompanied by a ferromagnetic to antiferromagnetic transition around x = 0.2, which is attributed to the double-exchange interactions between A-site Mn2+ and B-site Mn3+. Partial charge disproportionation of the B-site Mn3+ into Mn2+ and Mn4+ occurs for x above 0.8 samples as manifested by X-ray spectrum and magnetic behaviors. The coexistence of B-site Mn3+ (Jahn–Teller distortion ion) and B′-site Ta5+ (second-order Jahn–Teller distortion ion) could be energetically responsible for the absence of A-site columnar ordering as observed in other quadruple perovskites with half of the A-sites occupied by small transition-metal cations. These exceptional findings indicate that exotic perovskites can be successfully stabilized at chemical and intermediate physical pressure, and the presence of Jahn–Teller distortion cations at the same lattice should be avoided to enable cationic ordering.

The novel two-dimensional honeycomb layered Cu3LiRu2O6 exhibits Pauli-like paramagnetic and Mott variable range hopping semiconduction behaviors, which contradict the large specific-heat Sommerfeld coefficient for metals, and indicate a possible spin-excitation induced nonmetallic metal. This nonmetallic feature can be significantly suppressed by pressure toward producing a bad-metal state, as reflected by the temperature-dependent resistivity response up to 35 GPa.

Two-dimensional (2D) materials have been widely applied in electrochemical conversion technologies, especially toward the water oxidation reaction (WOR) in metal–air batteries and water splitting. Here, we demonstrate a facile ligand-assisted synthetic method, promoting the transformation of 2D layered double hydroxides (LDHs) into 2D metal–organic frameworks (MOFs). The CoFe-LDH precursor acts as an adjustable metal release source, controlling heterogeneous nucleation for 2D MOFs. Compared with most cobalt-based electrocatalysts, the optimized CoFe 2D MOFs exhibit a superior WOR performance on glassy-carbon electrodes (overpotential of 274 mV at 10 mA cm−2 and a Tafel slope of 46.7 mV dec−1) and long-term stability, due to the unique 2D characteristics and coupling effect between Co and Fe ions. More importantly, this work highlights the ability to transform 2D LDHs into 2D MOFs and reveals the intrinsic factors for excellent performance in the WOR.

We report high pressure studies on the C-type antiferromagnetic semiconductor EuTe2 up to 36.0 GPa. A structural transition from the I4/mcm to C2/m space group is identified at ~16 GPa. Superconductivity is discovered above ~5 GPa in both the I4/mcm and C2/m space groups. In the low-pressure phase (< 16 GPa), the antiferromagnetic transition temperature is enhanced with increasing pressure due to the enhanced magnetic exchange interactions. Magnetoresistance measurements indicate an interplay between the local moments of Eu2+ and the conduction electrons of Te 5p orbits. The upper critical field of the superconductivity is well above the Pauli limit. Across the structural transition to the high-pressure phase (> 16 GPa), EuTe2 becomes nonmagnetic and the superconducting transition temperature evolves smoothly with the upper critical field below the Pauli limit. Therefore, the high upper critical field of EuTe2 in the low-pressure phase is due to the exchange field compensation effect of the Eu magnetic order and the superconductivity in both structures may arise in the framework of the BCS theory., 11 pages,5 figures with 8 pages supplementary

A series of composites based on (100-x)wt.%Ce0.9Pr0.1O2-{\delta}-xwt.%Pr0.6Ca0.4FeO3-{\delta} (x = 25, 40 and 50) doped with the cheap and abundant alkaline earth metal Ca2+ at the A-site has been successfully designed and fabricated. The crystal structure, oxygen permeability, phase and CO2 stability were evaluated. The composition of 60wt.%Ce0.9Pr0.1O2-{\delta}-40wt.%Pr0.6Ca0.4FeO3-{\delta}(60CPO-40PCFO) possesses the highest oxygen permeability among three studied composites. At 1000 oC, the oxygen permeation fluxes through the 0.3 mm-thickness 60CPO-40PCFO membranes after porous La0.6Sr0.4CoO3-{\delta} each to 1.00 mL cm-2 min-1 and 0.62 mL cm-2 min-1 under air/He and air/CO2 gradients, respectively. In situ XRD results demonstrated that the 60CPO-40PCFO sample displayed a perfect structural stability in air as well as CO2-containing atmosphere. Thus, low-cost, Co-free and Sr-free 60CPO-40PCFO has high CO2 stability and is economical and environmental friendly since the expensive and volatile element Co was replaced by Fe and Sr was waived since it easily forms carbonates., Comment: 30 pages, 10 figures, 2 tables, post-print of the article published in journal of the european ceramic society (accepted)

Thermal ammonolysis of quasi-two-dimensional (quasi-2D) $\mathrm{Co}{\mathrm{Ta}}_{2}{\mathrm{O}}_{6}$ yields the ${\mathrm{O}}^{2\ensuremath{-}}/{\mathrm{N}}^{3\ensuremath{-}}$ and anionic vacancy-ordered ${\mathrm{Co}}^{2+}{\mathrm{Ta}}_{2}^{5+}{\mathrm{O}}_{6\ensuremath{-}x}{\mathrm{N}}_{2x/3}{\ensuremath{\square}}_{x/3}$ ($x\ensuremath{\le}0.15$), which exhibits a transition from antiferromagnetism to defect-engineered above-room-temperature ferromagnetism. First-principles calculations reveal that the origin of ferromagnetism is a particular $\mathrm{Co}{\mathrm{O}}_{5}\mathrm{N}$ configuration with N located at Wyckoff position $8j$, which breaks mirror symmetry about the $ab$ plane. A pressure-induced electronic phase transition is also predicted at $\ensuremath{\sim}24.5\phantom{\rule{0.16em}{0ex}}\mathrm{GPa}$, accompanied by insulator-to-metal transition and magnetic moment vanishing.

The rational design of multifunctional inorganic pigments relies on the manipulation of ionic valence and local surroundings of a chromophore in structurally and chemically habitable hosts. To date, the development of environmentally benign and intense violet/purple pigments is still a challenge. Here we report a family of A3-xMnxTeO6 and A3-2xMnxLixTeO6 (A = Zn, Mg; x = 0.01-0.15) pigments colored by site-selective Mn2+O4 yellow and Mn3+O5-6 violet chromophores. Zn2.9Mn0.1TeO6 is intense bright yellow, comparable with commercial BiVO4, and has better near-infrared reflectivity (∼89%) in comparison to commercial TiO2. The codoped Li+ "activator" generates holes and charge-balanced Mn3+ (Mn3+O5-6), realizing a color transformation from yellow to the bright violet pigments of A3-2xMnxLixTeO6. The most vivid Mg2.8Mn0.1Li0.1TeO6 is probably the best violet pigment known to date, exhibits excellent chemical and thermodynamic stability, and demonstrates pressure-dependent stability up to 5-7 GPa, before a (reversible) phase transition to pink. Theoretical calculations revealed the correlation between site-preference occupancy and chromophore motifs and predicted a wide color gamut of pigments in Zn3TeO6-hosted 3d transition-metal ions other than manganese.

High stability and oxygen permeability are two prominent requirements for the oxygen transport membrane candidates used as industrialization. Herein, we report several composite membranes based on xwt.%Ce0.9Pr0.1O2(CPO)-(100-x)wt.%Pr0.6Sr0.4Fe0.8Al0.2O3(PSFAO) (x = 50, 60 and 75) prepared via a modified Pechini method. Oxygen permeability test reveals that the 60CPO-40PSFAO composition exhibits the highest oxygen permeability. The oxygen permeation flux through the optimal uncoated 0.33 mm-thickness 60CPO-40PSFAO composite can reach 1.03 mL cm-2 min-1 (over the general requirement value of 1 mL cm-2 min-1) in air/He atmosphere at 1000 {\deg}C. In situ XRD performance confirms the optimal 60CPO-40PSFAO sample shows excellent stability in CO2-containing atmospheres. The 60CPO-40PSFAO membrane still exhibits simultaneously excellent oxygen permeability and phase stability after operating for over 100 h at air/CO2 condition at 1000 {\deg}C, which further indicates that the 60CPO-40PSFAO composite is likely to be used for oxygen supply in CO2 capture, Comment: 29 pages,12 figures, 1 table

A quadruple perovskite LaMn3Rh4O12 with A′ = Mn and B = 4d transition metal was synthesized at high pressure (8 GPa) and temperature (1423 K) for the first time. Room temperature powder X-ray diffr...

A new polymorph of the triple perovskite Ba3CuOs2O9, which usually exists in the orthorhombic phase, was synthesized under high-pressure and high-temperature conditions at 6 GPa and 1100 °C. Under the synthetic condition, Ba3CuOs2O9 crystallizes into a hexagonal structure (P63/mmc) with a = 5.75178(1) A and c = 14.1832(1) A, and undergoes a 1.36% increment in density, compared to that of the orthorhombic phase. Although Ba3CuOs2O9 maintains its 6 H perovskite-type structure, the distribution of Cu and Os atoms are dramatically altered; (Cu)4a(Os,Os)8f transits to (Os)2a(Cu,Os)4f ordering over the corner- and face-sharing sites, respectively. The hexagonal Ba3CuOs2O9 exhibits a ferrimagnetic transition at 290 K, which is in stark contrast to the antiferromagnetic transition at 47 K exhibited by the orthorhombic Ba3CuOs2O9. The enhanced transition temperature is most likely due to the strongly antiferromagnetic Os5+–O–Os5+ bonds and the moderately antiferromagnetic Os5+–O–Cu2+ bonds, the angles of which are both approximately 180°. The 290 K ferrimagnetic transition temperature is the highest reported for triple-perovskite osmium oxides. Besides, the coercive field is greater than 70 kOe at 5 K, which is remarkable among the coercive fields of magnetic oxides.

Li2GeTeO6 prepared at ambient pressure adopts the corundum derivative ordered ilmenite structure (rhombohedral R3). When heated at 1073 K and 3–5 GPa, the as-made Li2GeTeO6 can convert into a LiSbO3-derived Li2TiTeO6-type phase (orthorhombic Pnn2), which is the third LiSbO3-derived double A2BB′O6 phase in addition to Li2TiTeO6 and Li2SnTeO6. This Pnn2 Li2GeTeO6 phase spontaneously reverts to the R3 phase if annealed up to 1023 K at ambient pressure. Although the crystal structural analyses and second harmonic generation measurements clearly demonstrate the polar nature of both the R3 and Pnn2 phases, P(E) and dielectric measurements do not show any convincing ferroelectric response. Given the large estimated spontaneous polarization (17 and 80 μC/cm2), the absence of ferroelectric behavior could be attributed to the random domain distribution and leakage due to Li-ion migration.

Predicted polymorph manipulation offers a cutting-edge route to design function-oriented materials in an exotic double perovskite-related oxide A2BB′O6 with small A-site cations. Herein, first-principles density functional theory calculations in light of the equation of state for solid, for the first time, was used to predict the Mg3TeO6 (R)-to-perovskite (P21/n) type phase transition in Mn3TeO6 at around 5 GPa, regardless of the deployment of magnetic interactions. The high-pressure synthesis and synchrotron diffraction crystal structure analysis corroborated experimentally the polymorph variation in Mn22+Mn2+Te6+O6, which was accompanied by a 13 K increase in the antiferromagnetic ordering temperature (37 K) in the high-pressure perovskite polymorph compared to that of the ambient-pressure R phase (24 K). The magnetodielectric coupling remains up to 50 K with the maximum being around the magnetic ordering temperature in the perovskite Mn3TeO6. Thus, the predicted polymorph manipulation here offers the possibility of discovering accelerated materials by inverse design in exotic perovskite oxides.

Exploring a simple model system to realize the intrinsic guidelines of activity for oxide electrocatalysts is urgent and important. Here, we introduce delafossite oxides A 2IrO3 (A = Li, Na, Cu) as a family of oxygen evolution reaction electrocatalysts in alkaline media. We show that, in Cu2IrO3, the intrinsic intersite charge transfer between Cu and Ir improves the electrocatalytic activity by simultaneously increasing the conductivity and reducing the Tafel slope down to 51 mV dec−1 with an overpotential η 10 = 361 mV. Through a comparative study, the improved activity of Cu2IrO3 is attributed to the increase of Ir 5d projected electronic density of states with extended Ir–O bond length. This study provides insights into advanced catalyst design through tailoring the active site of oxides by the modulation of electronic states in a given structural motif.

Double-perovskite Lu2NiIrO6 was synthesized at high pressure (6 GPa) and high temperature (1300 °C). Synchrotron powder X-ray diffraction indicates that its structure is a monoclinic double perovskite (space group P21/n) with a small, 11% Ni/Ir antisite disorder. X-ray absorption near-edge spectroscopy measurements established Ni2+ and Ir4+ formal oxidation states. Magnetic studies indicate a ferrimagnetic transition at 207 K. The low-temperature magnetization curve of Lu2NiIrO6 features broad hysteresis with a coercive field as high as 48 kOe. These results encourage the search for hard magnets in the class of 3d/5d double-perovskite oxides.

Compared to AgNbO3 based ceramics, the experimental investigations on the single crystalline AgNbO3, especially the ground state and ferroic domain structures, are not on the same level. Here, based on successfully synthesized AgNbO3 single crystal using a flux method, we observed the coexistence of ferroelastic and ferroelectric domain structures by a combination study of polarized light microscopy and piezoresponse force microscopy. This finding may provide a new aspect for studying AgNbO3. The result also suggests a weak electromechanical response from the ferroelectric phase of AgNbO3, which is also supported by the transmission electron microscope characterization. Our results reveal that the AgNbO3 single crystal is in a polar ferroelectric phase at room temperature, clarifying its ground state which is controversial from the AgNbO3 ceramic materials.

All inorganic lead cesium halide perovskites (CsPbX3, X = Cl, Br, I) nanocrystals (NCs) are supposed to be promising luminescent-converting materials for next-generation displays, on account of their excellent optical and photoelectric properties, facile synthesis, and low cost. However, the inherent poor stability hinders their implementation in practical applications. Here, we present a simple cooperative strategy for the synthesis of stable green perovskite composite luminophore powders. In a typical cooperative process, HF leads to the formation of PbBrF framework in which the green-emitting CsPbBr3 NCs that are transformed from the non-emitting precursors CsPb2Br5 NCs by hydration, are simultaneously embedded in. The obtained CsPbBr3/PbBrF composites NCs maintain photoluminescence quantum yield (∼ 30%) and narrow band emission (∼ 22 nm). Additionally, benefiting from the PbBrF framework with good thermal diffusivity and stability, CsPbBr3/PbBrF composite NCs show excellent stability to heat, radiation, and polar solvents, which can be used as promising green luminescent-converting materials in the next-generation displays.

Controlling and modulating the magnitude and signs of electric polarization in multiferroics are very important for practical applications. The magnetoelectric effect in multiferroic materials enables the control and tailor of electric polarization by a magnetic field or vice versa. However, there are rare investigations about the mutual control of the magnitude and signs of electric polarization in multiferroics. Here, we successfully synthesized single crystals of Y-type hexaferrites Ba0.8Sr1.2Co2Fe12-xAlxO22 (x = 0 and 1.08) via flux method. The magnetization, magnetodielectric and magnetoelectric properties were investigated. We found that Al-doping increased the conical magnetic structure transition temperatures and enhanced the magnetoelectric properties. Most importantly, both samples exhibited reversal and non-reversal polarizations at low and high temperatures, respectively. In addition, Al-doping can stabilize the non-reversal ferroelectric polarization, possibly originating from the different field-dependent magnetic structure transitions.

Polycrystalline samples of $\mathrm{B}{\mathrm{a}}_{3}\mathrm{NiO}{\mathrm{s}}_{2}{\mathrm{O}}_{9}$ were synthesized at ambient pressure (AP) and high pressure (HP) conditions, respectively. Both samples are electrically semiconducting. The AP $\mathrm{B}{\mathrm{a}}_{3}\mathrm{NiO}{\mathrm{s}}_{2}{\mathrm{O}}_{9}$ crystallizes in the $6H$ perovskite structure with space group $P{6}_{3}/mmc$, consisting of face-sharing $\mathrm{O}{\mathrm{s}}_{2}{\mathrm{O}}_{9}$ dimer units and corner-sharing $\mathrm{Ni}{\mathrm{O}}_{6}$ octahedra. Magnetic measurements indicated that AP $\mathrm{B}{\mathrm{a}}_{3}\mathrm{NiO}{\mathrm{s}}_{2}{\mathrm{O}}_{9}$ is antiferromagnetically ordered below 130 K. HP $\mathrm{B}{\mathrm{a}}_{3}\mathrm{NiO}{\mathrm{s}}_{2}{\mathrm{O}}_{9}$ crystallizes in the $6H$ perovskite structure too, but the face-sharing octahedral sites appear to be occupied by both $\mathrm{N}{\mathrm{i}}^{2+}$ and $\mathrm{O}{\mathrm{s}}^{5+}$ ions, whereas the corner-sharing site is occupied exclusively by $\mathrm{O}{\mathrm{s}}^{5+}$. HP $\mathrm{B}{\mathrm{a}}_{3}\mathrm{NiO}{\mathrm{s}}_{2}{\mathrm{O}}_{9}$ undergoes a high-temperature ($\ensuremath{\approx}\phantom{\rule{0.16em}{0ex}}400\phantom{\rule{0.16em}{0ex}}\mathrm{K}$) weak ferromagnetic transition, which is much different from the antiferromagnetism of the AP phase. The long-range magnetic order of HP $\mathrm{B}{\mathrm{a}}_{3}\mathrm{NiO}{\mathrm{s}}_{2}{\mathrm{O}}_{9}$ was confirmed by neutron powder diffraction. X-ray magnetic circular dichroism analysis supported ferromagnetic coupling between Os and Ni moments which leads to a spin arrangement, where the ferromagnetic moments mainly arise from $\mathrm{N}{\mathrm{i}}^{2+}$ ions.

X-type hexaferrites have been receiving considerable attention due to their promising applications in many magnetic-electronic fields. However, the growth of single-crystal X-type hexaferrite is still a challenge. Herein we reported, for the first time, the preparation of single crystal X-type hexaferrite Sr

Understanding the electric dipole switching in multiferroic materials requires deep insight of the atomic-scale local structure evolution to reveal the ferroelectric mechanism, which remains unclear and lacks a solid experimental indicator in high-pressure prepared LiNbO

Rational design of technologically important exotic perovskites is hampered by the insufficient geometrical descriptors and costly and extremely high-pressure synthesis, while the big-data driven compositional identification and precise prediction entangles full understanding of the possible polymorphs and complicated multidimensional calculations of the chemical and thermodynamic parameter space. Here we present a rapid systematic data-mining-driven approach to design exotic perovskites in a high-throughput and discovery speed of the A(2)BB'O-6 family as exemplified in A(3)TeO(6). The magnetoelectric polar magnet Co3TeO6, which is theoretically recognized and experimentally realized at 5 GPa from the six possible polymorphs, undergoes two magnetic transitions at 24 and 58 K and exhibits helical spin structure accompanied by magnetoelastic and magnetoelectric coupling. We expect the applied approach will accelerate the systematic and rapid discovery of new exotic perovskites in a high-throughput manner and can be extended to arbitrary applications in other families., National Science Foundation of ChinaNational Natural Science Foundation of China (NSFC) [NSFC-21875287, 21801253, 11804404]; Program for Guangdong Introducing Innovative and Entrepreneurial Teams [2017ZT07C069]; Institutional Strategy of the University of Cologne within the German Excellence Initiative; Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)German Research Foundation (DFG) [277146847 -SFB 1238]; DOEBESUnited States Department of Energy (DOE) [DE-SC0012704], We gratefully acknowledge the discussion of the piezoresponse behavior with Professor X. S. Gao at South China Normal University. This work was financially supported by the National Science Foundation of China (NSFC-21875287, 21801253, and 11804404), the Program for Guangdong Introducing Innovative and Entrepreneurial Teams (2017ZT07C069), and The Institutional Strategy of the University of Cologne within the German Excellence Initiative and the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - Projektnummer 277146847 -SFB 1238 (B02). The XANES work at the Brookhaven National Laboratory, NSLS-II was supported by the DOEBES (DE-SC0012704).

Y2CoRuO6 was synthesized as a B-site ordered double perovskite with distorted monoclinic P21/n symmetry and an average tilting of the CoO6 and RuO6 octahedra of ψ = 19.7°. DC magnetization measure...

The novel two-dimensional honeycomb layered Cu3LiRu2O6 exhibits Pauli-like paramagnetic and Mott variable range hopping semiconduction behaviors, which contradict the large specific-heat Sommerfeld coefficient for metals, and indicate a possible spin-excitation induced nonmetallic metal. This nonmetallic feature can be significantly suppressed by pressure toward producing a bad-metal state, as reflected by the temperature-dependent resistivity response up to 35 GPa.

Metal-organic frameworks (MOFs) have been recognized as compelling platforms for the development of miscellaneous applications because of their structural diversity and functional tunability. Here, we propose that the electrocatalytic properties could be well modified by incorporating missing linkers into the MOF. Theoretical calculations suggest the electronic structure of MOFs can be tuned by introducing missing linkers, which improves oxygen evolution reaction (OER) performance of the MOF. Inspired by these aspects, we introduced various missing linkers into a layered-pillared MOF Co2(OH)2(C8H4O4) (termed as CoBDC) to prepare missing-linker MOFs. Transmission electron microscope and synchrotron X-ray measurements confirmed that the missing linkers in the MOF could be introduced and well controlled by our strategy. The self-supported MOF nanoarrays with missing linkers of carboxyferrocene exhibit excellent OER performance with ultralow overpotential of 241 mV at 100 mA cm−2. This work opens a new prospect to develop efficient MOF-based electrocatalysts by introducing missing linkers., While water splitting electrocatalysis provides a means to store electrical energy as fuel, the water oxidation catalysts typically show low performances. Here, authors employ metal-organic frameworks with missing-linkers as highly active oxygen evolution electrocatalysts.

Transition-metal-only perovskite oxides can introduce additional magnetic functionality with robust magnetoelectric properties but are rare. In this work we prepared a new transition-metal-only perovskite Mn2(Fe0.8Mo0.2)MoO6 at high pressure and temperature. Uniquely, Mn2(Fe0.8Mo0.2)MoO6 was discovered as a line phase upon composition modulation that was motivated from the above-room-temperature multiferroic Mn2FeMoO6 corundum phase. It exhibits ferrimagnetic Fe–Mo sublattice (TC = 194 K) and Mn sublattice antiferromagnetic (Tm ∼ 45 K) transitions. Below Tm the two sublattice orderings are coupled and give rise to canted components in both. A first-order field-induced transition is also observed below 45 K. Mn2(Fe0.8Mo0.2)MoO6 is a Mott variable range hopping semiconductor. These findings for the first time show that either an exotic perovskite or a corundum phase can be achieved by composition modulation besides the pressure effect.