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Single crystals of a new titanium oxysulfide, LiLa 3 Ti 2 S 3 O 6 , were grown from a KI molten salt. Single-crystal X-ray diffraction analysis revealed that LiLa 3 Ti 2 S 3 O 6 crystallizes in the space group Pnma with lattice parameters of a = 11.7319(4) Å, b = 3.94787(14) Å, and c = 20.6885(6) Å. In this structure, the one-dimensional chains of corner-sharing TiO 5 S octahedra are further corner-linked via equatorial and apical oxygen atoms to form unique corrugated two-dimensional perovskite-type layers in the ab plane with one octahedral thickness. These layers were intervened along the c -axis by the LaS rock-salt layers corrugated concomitantly with the perovskite-type layers, and LiO 2 S 2 tetrahedral chains were located between these two types of two-dimensional layers. LiLa 3 Ti 2 S 3 O 6 can be viewed as a modified K 2 NiF 4 -type structure with TiO 5 S octahedral layers stacked in a zigzag manner along the c axis. The oxysulfide has a direct-type band gap of 1.85 eV, based on UV-vis-NIR diffuse reflectance measurements. First-principles calculations showed that the conduction band minimum mainly consists of Ti 3 d orbitals, and the valence band maximum consists of S 3 p, O 2 p , and Li 2s orbitals. The electronic structures near the Fermi level are similar to those of the structurally related photocatalytic oxysulfides Y 2 Ti 2 S 2 O 5 and La 5 Ti 2 CuS 5 O 7 .

In this study, we successfully synthesized the double perovskite oxide Cd 2 FeReO 6 by using a high-temperature and high-pressure method. The crystal structure was confirmed to belong to the P 2 1 / n space group, exhibiting approximately 68% ordering of Fe 3+ and Re 5+ ions at the perovskite B-site with the remaining regions showing antisite disorder. The measured Curie temperature of Cd 2 FeReO 6 was 460 K, slightly lower than expected but still significantly above room temperature. Remarkably, Cd 2 FeReO 6 displayed a remarkable low-field butterfly type tunneling magnetoresistance of -23% (-37% between the lowest and the largest values) at 5 K and 90 kOe, the highest among the A 2 FeReO 6 ( A = Ca, Sr, Pb, Ba) family. First-principles calculations provided insight into the origin of this observed magnetoresistance behavior, revealing Cd 2 FeReO 6 's half-metallic ferrimagnetic nature. This research extends our understanding of the double perovskite family and emphasizes its potential significance in the domains of spintronics and materials science. The exploration of differing magnetoresistance behaviors between Cd 2 FeReO 6 and Ca 2 FeReO 6 , along with the influence of antisite disorder in Cd 2 FeReO 6 , opens intriguing avenues for further research.

Band gap engineering using multiple anions is an established approach to novel photocatalysts that exhibit suitable band gap energies for water splitting and high photocorrosion resistance. However, few studies have been conducted on photocatalysts with polyanions, including polychalcogenide ions. Here, we present a new quaternary gallium oxysulfide with disulfide pairs (S 2 ) 2- , La 4 Ga 2 S 8 O 3 , grown out of a KI molten salt. Single-crystal X-ray diffraction analysis revealed that the oxysulfide crystallizes in the orthorhombic space group Pbcn with lattice constants of a = 18.3330(6) Å, b = 13.0590(5) Å, and c = 5.9022(3) Å. In the crystal structure, the GaS 4 -based zigzag chains and OLa 4 -based fluorite-like strips are independently arranged in two dimensions, which alternately stack via the disulfide pairs along the third direction. The oxysulfide is a direct-type semiconductor with a band gap of 2.45 eV. First-principles calculations combined with X-ray photoemission spectroscopy measurements show that S 3p states derived from the disulfide pairs dominate the valence band maximum and conduction band minimum, and these band-edge positions are suitable for the oxidation and reduction of water. Our comprehensive study based on the electronic structure suggests that the disulfide pairs make La 4 Ga 2 S 8 O 3 a potential photocatalyst for water splitting under visible-light irradiation.

Under high-pressure and high-temperature conditions, doped Bi 3 Re 3 O 11 and Bi 3 Os 3 O 11 with Fe up to 29 atomic % were synthesized. The crystal structures and chemical compositions of Bi 3 Os 2.45 Fe 0.55 O 11 and Bi 3 Re 2.13 Fe 0.87 O 11 were determined by synchrotron powder X-ray diffraction and electron probe microanalysis. Both crystal structures were explained by a KSbO 3 -type model with the space group Pn 3̅. Magnetic and electronic transport property measurements showed that Bi 3 Os 2.45 Fe 0.55 O 11 exhibited a ferrimagnetic transition at the highest magnetic ordering temperature of 490 K in the KSbO 3 -type, while Bi 3 Re 2.13 Fe 0.87 O 11 exhibited a spin glassy behavior below 22 K. The magnetoresistance at 5 K and 90 kOe was almost zero for Bi 3 Os 2.45 Fe 0.55 O 11 , but -10% for Bi 3 Re 2.13 Fe 0.87 O 11 . These results suggest that KSbO 3 - type 5d oxides, which exhibit only weak temperature-dependent paramagnetism to date, are a group of compounds that can be converted into spintronic materials by doping with 3d elements, leading to the development of new KSbO 3 -type materials with both theoretical and practical significance.

A new ternary chromium disulfide, Ba 9 Cr 4 S 19 , has been grown out of BaCl 2 molten salt. Single-crystal structure analysis revealed that it crystallizes in the centrosymmetric space group C 2/ c with lattice parameters: a = 12.795(3) Å, b = 11.3269(2) Å, c = 23.2057(6) Å, β = 104.041(3)°, and Z = 4. Ba 9 Cr 4 S 19 comprises four face-sharing Cr-centered octahedra with disulfide ions occupying sites on each terminal face. The resulting Cr 4 S 15 tetramer units are isolated by nonmagnetic Ba-centered polyhedra in the ab plane and barium disulfide (=Ba 4 (S 2 ) 2 ) layers along the c -axis. Following the structure analysis, the title compound should be expressed as [Ba 2+ ] 9 [Cr 3+ ] 4 [(S 2 ) 2- ] 4 [S 2- ] 11 , which is also consistent with Cr2p X-ray photoemission spectra showing trivalent states of the Cr atoms. The unique Cr-based zero-dimensional structure with the formation of these disulfide ions can be achieved for the first time in ternary chromium sulfides, which adopt 1-3 dimensional frameworks of Cr-centered polyhedra., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

Polycrystalline Sr 3 OsO 6 , which is an ordered double-perovskite insulator, is synthesized via solid-state reaction under high-temperature and high-pressure conditions of 1200 °C and 6 GPa. The synthesis enables us to conduct a comparative study of the bulk form of Sr 3 OsO 6 toward revealing the driving mechanism of 1000 K ferromagnetism, which has recently been discovered for epitaxially grown Sr 3 OsO 6 films. Unlike the film, the bulk is dominated by antiferromagnetism rather than ferromagnetism. Therefore, robust ferromagnetic order appears only when Sr 3 OsO 6 is under the influence of interfaces. A specific heat capacity of 39.6(9) × 10 -3 J mol -1 K -2 is found at low temperatures (<17 K). This value is remarkably high, suggesting the presence of possible Fermionic-like excitations at the magnetic ground state. Although the bulk and film forms of Sr 3 OsO 6 share the same lattice basis and electrically insulating state, the magnetism is entirely different between them.

Crystallization that proceeds above the glass transition temperature upon heating the glassy or amorphous state is referred to as "cold crystallization", which has often been observed in supercooled phases of molecular materials followed by the transition to the thermodynamically stable crystalline phase. Although this behavior is common for the macromolecules with high structural flexibility among segments preserving the wide temperature range of corresponding glassy phases, cold crystallization of small molecules is relatively rare and there is still less knowledge on the design guideline of such molecules. Here we report a ferrocene-hinged molecule D C12 carrying two units of didodecyl-substituted pentathiophenes at the 1,1'-positions. Due to the rotational freedom of the ferrocene unit, D C12 forms amorphous solid on cooling from its isotropic melt. The amorphous state was realized even by slow cooling such as 0.1 °C min -1 . The possible reason for the easy formation of the amorphous phase is the coexistence of various conformations of D C12 originating from the open conformers of the ferrocene. On heating from the amorphous phase, D C12 shows cold crystallization with the estimated activation energy of 61 kJ mol -1 . The crystalline phase is composed of the closed form of D C12 molecules packed in a lamellar fashion, and the degree of crystallinity is remarkably high compared with the case of macromolecular materials. The crystallization is triggered by the intermolecular interactions among the dodecyl chains and rotational flexibility of the ferrocene unit. This work provides an unprecedented example that ferrocenes act as heat-controllable rotational hinges in condensed phases. Considering that the cold crystallization phenomenon is related to heat-storage materials, the design strategy presented in this work will be novel to realize both easily formed amorphous phases and highly crystalline phases formed through cold crystallization.

Hybridization of coordination polymers allows for combining two or more distinct structures into one material. Here, we explore the core/shell-type materials of Prussian blue analogues (PBAs) by heteroepitaxial growth and demonstrate how one phase structurally dominates the other. The volumetric ratio between the shell and core crystals determine the final structure of the hybrids. The outermost dominated the Na + ion insertion/extraction, illustrating how the hybridization can adjust the function of PBAs.

The crystal structure of HgPbO 3 was studied using single-crystal X-ray diffraction and powder synchrotron X-ray diffraction. The structure was well characterized as a centrosymmetric model with a space group of R-3 m [hexagonal setting: a = 5.74413(6) Å and c = 7.25464(8) Å] rather than as a noncentrosymmetric model as was expected. It was found that Pb 4+ is octahedrally coordinated by six oxygen atoms as usual, while Hg 2+ is coordinated by three oxygen atoms in a planar manner, this being a very rare coordination of Hg in a solid-state material. The magnetic and electronic transport properties were investigated in terms of the magnetic susceptibility, magnetization, Hall coefficient, and specific heat capacity of polycrystalline HgPbO 3 . Although HgPbO 3 has a carrier concentration (=7.3-8.5 × 10 20 cm -3 ) that is equal to that of metallic oxides, the very weak temperature dependence of the electrical resistivity (residual-resistivity ratio ∼1.5), the significant diamagnetism (= -1.02 × 10 -4 emu mol -1 at 300 K) that is in the same order of that of Bi powder and the remarkably small Sommerfeld coefficient [=1.6(1) × 10 -3 J mol -1 K -2 ] implied that it is semimetallic in nature. HgPbO 3 does not have a cage structure; nevertheless, at temperatures below approximately 50 K, it clearly exhibits phonon excitation of an anharmonic vibrational mode that is as significant as those of RbOs 2 O 6 . The mechanism of the anharmonic mode of the HgPbO 3 has yet to be identified, however.

We report the successful synthesis of three new Ruddlesden-Popper-type scandium oxychloride perovskites, Sr 2 ScO 3 Cl, Sr 3 Sc 2 O 5 Cl 2 , and Ba 3 Sc 2 O 5 Cl 2 , by conventional solid-state reaction. Small single crystals of Sr 2 ScO 3 Cl were obtained by a self-flux method, and the crystal structure was determined to belong to the tetragonal P4/ nmm space group ( a = 4.08066(14) Å, c = 14.1115(8) Å) by X-ray diffraction analysis. The scandium center forms a ScO 5 Cl octahedron with ordered apical oxygen and chlorine anions. The scandium cation, however, is shifted from the position of the octahedral center toward the apical oxygen anion, such that the coordination geometry of the Sc cation can be effectively viewed as an ScO 5 pyramid. These structural features in the oxychloride are different from those of octahedral ScO 5 F coordinated with a partial O/F anion order at the apical sites in the oxyfluoride Sr 2 ScO 3 F. Rietveld refinements of the neutron powder diffraction data of Sr 3 Sc 2 O 5 Cl 2 ( I4/ mmm: a = 4.107982(5) Å, c = 23.58454(7) Å) and Ba 3 Sc 2 O 5 Cl 2 ( I4/ mmm: a = 4.206920(5) Å, c = 24.54386(6) Å) reveal the presence of pseudo ScO 5 pyramids with the Cl anion being distant from the scandium cation, which is similar to the Sc-centered coordination geometry in Sr 2 ScO 3 Cl with the exception that the ScO 5 pyramids form double layers by sharing the apical oxygen. Density functional calculations on Sr 2 ScO 3 Cl indicate the strong covalency of the Sc-O bonds but almost nonbonding interaction between Sc and Cl ions.

An umpolung reaction of the α-imino thioester was examined, and we found that α-imino thioesters were more effective substrates for the umpolung N-alkylation than conventional α-imino esters and they gave N-alkylated amino thioesters in high yields under mild reaction conditions in a short time. A new type of C-C bond formation followed by an unexpected rearrangement of the alkylthio group took place with the unsaturated ketones to afford the β-alkylthio-α-amino thioesters in high yields with good diastereoselectivity.

We have successfully synthesized Sr2MnO3F, a new layered perovskite oxyfluoride with a n = 1 Ruddlesden-Popper-type structure using a high-pressure, high-temperature method. Structural refinements against synchrotron X-ray diffraction data collected from manganese oxyfluoride demonstrated that it crystallizes in a tetragonal cell with the space group I4/mmm, in which the Mn cation is located at the octahedral center position. This is in stark contrast to the related oxyhalides that have square-pyramidal coordination such as Sr2MO3X (M = Fe, Co, Ni; X = F, Cl) and Sr2MnO3Cl. There was no evidence of O/F site order, but close inspection of the anion environment centered at the Mn cation on the basis of bond-valence-sum calculation suggested preferential occupation of the apical sites by the F ion with one oxide ion in a random manner. Magnetic susceptibility and heat capacity measurements revealed an antiferromagnetic ordering at 133 K (=TN), which is much higher than that of the chloride analogue with corrugated MnO2 planes (TN = 80 K).

Double-perovskite oxides Ca2MgOsO6 and Sr2MgOsO6 have been synthesized under high-pressure and high-temperature conditions (6 GPa and 1500 °C). Their crystal structures and magnetic properties were studied by a synchrotron X-ray diffraction experiment and by magnetic susceptibility, specific heat, isothermal magnetization, and electrical resistivity measurements. Ca2MgOsO6 and Sr2MgOsO6 crystallized in monoclinic (P21/n) and tetragonal (I4/m) double-perovskite structures, respectively; the degree of order of the Os and Mg arrangement was 96% or higher. Although Ca2MgOsO6 and Sr2MgOsO6 are isoelectric, a magnetic-glass transition was observed for Ca2MgOsO6 at 19 K, while Sr2MgOsO6 showed an antiferromagnetic transition at 110 K. The antiferromagnetic-transition temperature is the highest in the family. A first-principles density functional approach revealed that Ca2MgOsO6 and Sr2MgOsO6 are likely to be antiferromagnetic Mott insulators in which the band gaps open, with Coulomb correlations of ∼1.8-3.0 eV. These compounds offer a better opportunity for the clarification of the basis of 5d magnetic sublattices, with regard to the possible use of perovskite-related oxides in multifunctional devices. The double-perovskite oxides Ca2MgOsO6 and Sr2MgOsO6 are likely to be Mott insulators with a magnetic-glass (MG) transition at ∼19 K and an antiferromagnetic (AFM) transition at ∼110 K, respectively. This AFM transition temperature is the highest among double-perovskite oxides containing single magnetic sublattices. Thus, these compounds offer valuable opportunities for studying the magnetic nature of 5d perovskite-related oxides, with regard to their possible use in multifunctional devices.

The polycrystalline MO2's (HP-PdF2-type MO2, M = Rh, Os, Pt) with high-pressure PdF2 compounds were successfully synthesized under high-pressure conditions for the first time, to the best of our knowledge. The crystal structures and electromagnetic properties were studied. Previously unreported electronic properties of the polycrystalline HP-PdF2-type RuO2 and IrO2 were also studied. The refined structures clearly indicated that all compounds crystallized into the HP-PdF2-type structure, M(4+)O(2-)2, rather than the pyrite-type structure, M(n+)(O2)(n-) (n < 4). The MO2 compounds (M = Ru, Rh, Os, Ir) exhibited metallic conduction, while PtO2 was highly insulating, probably because of the fully occupied t2g band. Neither superconductivity nor a magnetic transition was detected down to a temperature of 2 K, unlike the case of 3d transition metal chalcogenide pyrites.

5d and 3d hybrid solid-state oxide Ca2FeOsO6 crystallizes into an ordered double-perovskite structure with a space group of P2₁/n with high-pressures and temperatures. Ca2FeOsO6 presents a long-range ferrimagnetic transition at a temperature of ~320 K (T(c)) and is not a band insulator, but is electrically insulating like the recently discovered Sr2CrOsO6 (T(c) ~725 K). The electronic stat of Ca2FeOsO6 is adjacent to a half-metallic state as well as that of Sr2CrOsO6. In addition, the high-T(c) ferrimagnetism was driven by lattice distortion, which was observed for the first time among double-perovskite oxides and represents complex interplays between spins and orbitals. Unlike conventional ferrite and garnet, the interplays likely play a pivotal role of the ferrimagnetism. A new class of 5d-3d hybrid ferrimagnetic insulators with high-T(c) is established to develop practically and scientifically useful spintronic materials.

In continuation of the series of perovskite oxides that includes 3d(4) cubic BaFeO3 and 4d(4) cubic BaRuO3, 5d(4) cubic BaOsO3 was synthesized by a solid-state reaction at a pressure of 17 GPa, and its crystal structure was investigated by synchrotron powder X-ray diffraction measurements. In addition, its magnetic susceptibility, electrical resistivity, and specific heat were measured over temperatures ranging from 2 to 400 K. The results establish a series of d(4) cubic perovskite oxides, which can help in the mapping of the itinerant ferromagnetism that is free from any complication from local lattice distortions for transitions from the 3d orbital to the 5d orbital. Such a perovskite series has never been synthesized at any d configuration to date. Although cubic BaOsO3 did not exhibit long-range ferromagnetic order unlike cubic BaFeO3 and BaRuO3, enhanced feature of paramagnetism was detected with weak temperature dependence. Orthorhombic CaOsO3 and SrOsO3 show similar magnetic behaviors. CaOsO3 is not as conducting as SrOsO3 and BaOsO3, presumably due to impact of tilting of octahedra on the width of the t2g band. These results elucidate the evolution of the magnetism of perovskite oxides not only in the 5d system but also in group 8 of the periodic table.

Extended layered oxyhalide compounds, Sr2NiO3X (X = F, Cl), with the square pyramidal coordination around the trivalent nickel ions in the low spin state (S = 1/2), are successfully synthesized by a high-pressure and high-temperature reaction. Both these compounds crystallize in the n = 1 Ruddlesden-Popper type structure, but the difference of halogen anions incorporated dictate the anion-site ordering patterns and the magnetic ground states. Sr2NiO3F adopts the tetragonal cell in the space group I4/mmm (a = b = 3.79125(2) Å and c = 13.13754(9) Å), with O/F anions being disordered at the apical sites, while the crystal structure of Sr2NiO3Cl is described in the tetragonal space group P4/nmm (a = b = 3.85566(1) Å and c = 14.43240(6) Å) with O/Cl anions being fully ordered at the apical sites. Additionally, Sr2NiO3Cl undergoes a long-range antiferromagnetic order below TN = 33 K, while the fluorine counterpart does not exhibit a long-range ordering but spin glass transition at T(SG) = 11 K. In light of the positive Weiss temperatures for both X = F and Cl, the unpaired electron likely occupies a d(xy) orbital. Namely, the superexchange interaction mediated by d(xy)-Opπ-d(xy) in the NiO2 basal plane is antiferromagnetic, while the direct exchange interaction between d(xy)-d(xy) along the diagonal directions is ferromagnetic. The origin of spin glass behavior observed in X = F is probably due to randomness of the direct d(xy)-d(xy) bonds caused by off-centering nickel ions and O/F site disordering.

Carbon-for-nitrogen substitution (51 at% at most) was achieved in the antiferromagnetic metallic host material Mn(3)ZnN. The various carbon-doped compounds were studied using synchrotron X-ray diffraction, and their electrical resistivities, specific heats, and degrees of magnetization were measured for temperatures of 2-400 K. The sharp antiferromagnetic-to-paramagnetic transition of the host material at 185 K broadened markedly as the carbon content was increased, and a significant ferromagnetic character was found to coexist with the antiferromagnetism when the carbon concentration exceeded 27 at%. This critical magnetic behavior is likely in part due to the increase in the density of states at the Fermi level and the increase in the distance between neighboring Mn atoms. The exact mechanism responsible for the induction of the complicated magnetic state could not be determined. However, the results demonstrate clearly that the chemical tuning of the X site in antiperovskite Mn(3)AX materials is as useful as that of the A and Mn sites and can be used to develop the properties of these materials for practical applications.

The postspinel mineral MgAl(2)O(4) exists only under the severe pressure conditions in the subducted oceanic lithosphere in the Earth's deep interior. Here we report that its analogous oxide CdRh(2)O(4) exhibits a structural transition to a quenchable postspinel phase under a high pressure of 6 GPa at 1400 °C, which is within the general pressure range of a conventional single-stage multianvil system. In addition, the complex magnetic contributions to the lattice and metal nonstoichiometry that often complicate investigations of other analogues of MgAl(2)O(4) are absent in CdRh(2)O(4). X-ray crystallography revealed that this postspinel phase has an orthorhombic CaFe(2)O(4) structure, thus making it a practical analogue for investigations into the geophysical role of postspinel MgAl(2)O(4). Replacement of Mg(2+) with Cd(2+) appears to be effective in lowering the pressure required for transition, as was suggested for CdGeO(3). In addition, Rh(3+) could also contribute to this reduction, as many analogous Rh oxides of aluminous and silicic minerals have been quenched from lower-pressure conditions.

The crystal structure of the layered cobalt oxyfluoride Sr(2)CoO(3)F synthesized under high-pressure and high-temperature conditions has been determined from neutron powder diffraction and synchrotron powder diffraction data collected at temperatures ranging from 320 to 3 K. This material adopts the tetragonal space group I4/mmm over the measured temperature range and the crystal structure is analogous to n = 1 Ruddlesden-Popper type layered perovskite. In contrast to related oxyhalide compounds, the present material exhibits the unique coordination environment around the Co metal center: coexistence of square pyramidal coordination around Co and anion disorder between O and F at the apical sites. Magnetic susceptibility and electrical resistivity measurements reveal that Sr(2)CoO(3)F is an antiferromagnetic insulator with the Néel temperature T(N) = 323(2) K. The magnetic structure that has been determined by neutron diffraction adopts a G-type antiferromagnetic order with the propagation vector k = (1/2 1/2 0) with an ordered cobalt moment μ = 3.18(5) μ(B) at 3 K, consistent with the high spin electron configuration for the Co(3+) ions. The antiferromagnetic and electrically insulating states remain robust even against 15%-O substation for F at the apical sites. However, applying pressure exhibits the onset of the metallic state, probably coming from change in the electronic state of square-pyramidal coordinated cobalt., (© 2012 American Chemical Society)

Single-crystal Ca(10)(Pt(4)As(8))(Fe(1.8)Pt(0.2)As(2))(5) superconducting (SC) nanowhiskers with widths down to hundreds of nanometers were successfully grown in a Ta capsule in an evacuated quartz tube by a flux method. Magnetic and electrical properties measurements demonstrate that the whiskers have excellent crystallinity with critical temperature of up to 33 K, upper critical field of 52.8 T, and critical current density of J(c) of 6.0 × 10(5) A/cm(2) (at 26 K). Since cuprate high-T(c) SC whiskers are fragile ceramics, the present intermetallic SC whiskers with high T(c) have better opportunities for device applications. Moreover, although the growth mechanism is not understood well, the technique can be potentially useful for growth of other whiskers containing toxic elements., (© 2012 American Chemical Society)

CaFeO(2), a material exhibiting an unprecedented layered structure containing 3d(6) iron in a high-spin distorted square-planar coordination, is reported. The new phase, obtained through a low-temperature reduction procedure using calcium hydride, has been characterized through powder neutron diffraction, synchrotron X-ray diffraction, Mossbauer spectroscopy, XAS experiments as well as first-principles DFT calculations. The XAS spectra near the Fe-K edge for the whole solid solution (Sr(1-x)Ca(x))FeO(2) supports that iron is in a square-planar coordination for 0

The recently discovered SrFeO2 prepared by a soft chemical route from a precursor SrFeO3 has the "infinite layer" (IL) structure with an unprecedented FeO4 square-planar coordination. We show that the IL structure has significant solubility to yield Sr1-xCaxFeO2 (0