Self-flux-grown BaFeClO crystals exhibiting structures with tunable modulation.

The synthesis and X-ray structural study of the new family of compounds BaFeClO with tunable structural modulation are reported. The framework of the structure has the BaFeO composition, with open hexagonal channels extending along the -axis. The channels are filled with linear [Ba-Cl-Ba] triplets.

Ultrasensitive 3D Aerosol-Jet-Printed Perovskite X-ray Photodetector.

X-ray photon detection is important for a wide range of applications. The highest demand, however, comes from medical imaging, which requires cost-effective, high-resolution detectors operating at low-photon flux, therefore stimulating the search for novel materials and new approaches. Recently, hybrid halide perovskite CHNHPbI (MAPbI) has attracted considerable attention due to its advantageous optoelectronic properties and low fabrication costs.

High-Pressure Synthesis of Rare-Earth Borate-Nitrate Crystals for Second Harmonic Generation.

The crystals of a novel family of rare-earth borate-nitrate compounds, (BO)(NO)NO ( = Pr, Nd), were grown at high-pressure in KAs flux and their crystal structure was determined. The new type of the crystalline structure consists of parallel chains of octahedra connected by common faces and forming the channels with the NO triangular planar motifs in the center, and isolated O tetrahedra separated from each other by N triangular motifs. Each NO triangle is in fact a part of rather unusual (NBO) block consisting of 3 distorted BO tetrahedra around central nitrogen atom.

Incommensurate crystal structure of PbHfO.

Controversy in the description/identification of so-called intermediate phase(s) in PbHfO, stable in the range ∼420-480 K, has existed for a few decades. A synchrotron diffraction experiment on a partially detwinned crystal allowed the structure to be solved in the superspace group Imma(00γ)s00 (No. 74.

Pressure-induced transformation of CHNHPbI: the role of the noble-gas pressure transmitting media.

The photovoltaic perovskite, methylammonium lead triiodide [CHNHPbI (MAPbI)], is one of the most efficient materials for solar energy conversion. Various kinds of chemical and physical modifications have been applied to MAPbI towards better understanding of the relation between composition, structure, electronic properties and energy conversion efficiency of this material. Pressure is a particularly useful tool, as it can substantially reduce the interatomic spacing in this relatively soft material and cause significant modifications to the electronic structure.

SrPt As: a layered incommensurately modulated metal with saturated resistivity.

The high-pressure synthesis and incommensurately modulated structure are reported for the new compound SrPt As, with = 0.715 (5). The structure consists of SrPtAs layers alternating with Pt-only corrugated grids.

Incommensurate atomic density waves in the high-pressure IVb phase of barium.

The host-guest structures of elements at high pressure discovered a decade ago still leave many open questions due to the lack of precise models based on full exploitation of the diffraction data. This concerns in particular Ba IV, which is stable in the range 12-45 GPa. With the example of phase Ba IVb, which is characterized here for the first time, a systematic analysis is presented of possible host-guest structure models based on high-quality single-crystal diffraction data obtained with synchrotron radiation at six different pressures between 16.

Optically switched magnetism in photovoltaic perovskite CHNH(Mn:Pb)I.

The demand for ever-increasing density of information storage and speed of manipulation boosts an intense search for new magnetic materials and novel ways of controlling the magnetic bit. Here, we report the synthesis of a ferromagnetic photovoltaic CHNH(Mn:Pb)I material in which the photo-excited electrons rapidly melt the local magnetic order through the Ruderman-Kittel-Kasuya-Yosida interactions without heating up the spin system. Our finding offers an alternative, very simple and efficient way of optical spin control, and opens an avenue for applications in low-power, light controlling magnetic devices.

CHNHPbI: precise structural consequences of water absorption at ambient conditions.

The crystal structure of the pristine (I) and aged (II) crystals of CHNHPbI (hereafter MAPbI) hybrid organic-inorganic lead iodide has been studied at 293 K with high-precision single-crystal X-ray diffraction using a synchrotron light source. We show that (I) and (II) are characterized by an identical tetragonal unit cell but different space groups: I422 for (I) and P422 for (II). Both space groups are subgroups of I4/mcm, which is widely used for MAPbI.

Crystal Structure, Transport, and Magnetic Properties of an Ir(6+) Compound Ba8Al2IrO14.

The novel iridate Ba8Al2IrO14 was prepared as single crystals by self-flux method, thereby providing a rare example of an all-Ir(VI) compound that can be synthesized under ambient pressure conditions. The preparation of all-Ir(6+) iridate without using traditional high-pressure techniques has to our knowledge previously only been reported in Nd2K2IrO7 and Sm2K2IrO7. The monoclinic crystal structure (space group C2/m, No.

Na(2/7)Gd(4/7)MoO4: a modulated scheelite-type structure and conductivity properties.

Scheelite-type compounds with the general formula (A1,A2)(n)[(B1,B2)O(4)](m) (2/3 ≤ n/m ≤ 3/2) are the subject of large interest owing to their stability, relatively simple preparation, and optical properties. The creation of cation vacancies (□) in the scheelite-type framework and the ordering of A cations and vacancies can be a new factor in controlling the scheelite-type structure and properties. For a long time, cation-deficient Nd(3+):M(2/7)Gd(4/7)□(1/7)MoO(4) (M = Li, Na) compounds were considered as potential lasers with diode pumping.

Crystal structure and optical and magnetic properties of Pr(2)(MoO(4))(3).

Praseodymium molybdate Pr(2)(MoO(4))(3) was synthesized using the standard ceramic route. The crystal structure of the material has been successfully solved in superspace group I2/b(alphabeta0)00 with lattice constants a = 5.30284(4), b = 5.

KSm(MoO(4))(2), an incommensurately modulated and partially disordered scheelite-like structure.

The incommensurately modulated scheelite-like KSm(MoO(4))(2) structure has been refined in the monoclinic superspace group I2/b(alphabeta0)00 by the Rietveld method on the basis of synchrotron radiation powder diffraction data. The systematic broadening of satellite reflections has been accounted for by applying anisotropic microstrain line-broadening. The microstructure has been studied by transmission electron microscopy (TEM).

Capabilities and limitations of a (3 + d)-dimensional incommensurately modulated structure as a model for the derivation of an extended family of compounds: example of the scheelite-like structures.

The previously reported incommensurately modulated scheelite-like structure KNd(MoO(4))(2) has been exploited as a natural (3 + 1)-dimensional superspace model to generate the scheelite-like three-dimensional structure family. Although each member differs in its space-group symmetry, unit-cell parameters and compositions, in (3 + 1)-dimensional space, they share a common superspace group, a common number of building units in the basic unit cell occupying Wyckoff sites with specific coordinates (x, y, z) and specific basic unit-cell axial ratios (c/a, a/b, b/c) and angles. Variations of the modulation vector q, occupation functions and t(0) are exploited for the derivation.

Hexagonal ferrites: a unified model of the (TS)nT series in superspace.

Hexagonal ferrites represent an extensive family of mixed-layer magnetic materials with periods up to 1500 A along the stacking direction, probably constituting the largest unit cells in the inorganic realm. The (TS)(n)T subfamily includes P3m1 and R3m structures that can be derived from Y ferrite Ba(2)M(2)Fe(12)O(22) (M = Zn, Fe, Co, Mg, Mn) by introducing stacking faults. A unified (3 + 1)-dimensional superspace model is proposed for all members of the (TS)(n)T family.

The room-temperature superstructure of ZrP2O7 is orthorhombic: there are no unusual 180 degrees P-O-P bond angles.

The structure of room-temperature ZrP2O7 is shown to be orthorhombic by a combination of high-resolution synchrotron powder diffraction and single-crystal synchrotron diffraction data. Small nontwinned single crystals were obtained by synthesizing the compound using solvothermal methods at temperatures below the cubic to orthorhombic phase transition. The average P-O-P angle is 146 degrees.

Getting more out of an incommensurately modulated structure: the example of K5Yb(MoO4)4.

A method based on the superspace approach is presented with the aim of generating a family of modular structures from a single incommensurately modulated structure. This approach based on the variation of the modulation vector q is applied to the generation of the K5Yb(MoO4)4, potassium ytterbium tetramolybdate, family of modular structures. The beta coefficient of the modulation vector q = betab* is a temperature-dependent variable which determines the modification.

A reinterpretation of the phase transitions in Na2CO3.

Based on the structural data of phases alpha (hexagonal; 756-972 K), beta (monoclinic; 605-751 K), gamma (incommensurate, monoclinic; 295 K) and delta (lock-in, monoclinic; 110 K) of sodium carbonate, Na2CO3, we could draw a parallel between the phase transitions and the evolution of the second coordination sphere of the C atoms. The temperature-dependent structures observed in the beta phase are reproduced in the incommensurate gamma phase as a modulation wave, which relates to the content of the symmetrically equivalent {110} lattice planes in the alpha phase. By decreasing the temperature, the phase transitions are associated with a stepwise increase in the number of Na ions participating in the second coordination sphere of the C atoms.

The role of second coordination-sphere interactions in incommensurately modulated structures, using beta-K5Yb(MoO4)4 as an example.

The incommensurate palmierite-like structure of beta-K5Yb(MoO4)4, potassium ytterbium tetramolydate, has been refined in the (3 + 1)-dimensional monoclinic superspace group X2/m(0rho0)00, with X = [0 0 0 0; (1/2) (1/2) 0 0; 0 0 (1/2) (1/2); (1/2) (1/2) (1/2) (1/2)] and the unit-cell parameters a = 10.4054 (16), b = 6.1157 (12), c = 19.

The commensurate composite sigma-structure of beta-tantalum.

The single-crystal investigation of the self-hosting sigma-structure of beta-tantalum (beta-Ta) at 120 K (low-temperature, LT, structure) and at 293 K (RT-I before cooling and RT-II after cooling and rewarming; RT represents room temperature) shows that this structure is indeed a specific two-component composite where the components have the same (or an integer multiple) lattice constants but different space groups. The space groups of both host (H) and guest (G) components cause systematic absences, which result from their intersection. The highest symmetry of a sigma-structure can be described as [H: P4(2)/mnm; G: P4/mbm (c(G) = 0.

The modulated structure of Ba0.39Sr0.61Nb2O6. I. Harmonic solution.

The structure of a crystal of Sr(0.61)Ba(0.39)Nb(2)O(6) has been solved and refined as an incommensurate structure in five-dimensional superspace.

The incommensurate structure of K3InPO42.

The incommensurately modulated structure of K(3)In(PO(4))(2) has been solved and refined. The origin of the modulation relates to the ordering of K cations within the hexagonal close packing of the PO(4) anions. The driving forces for the modulation of the other cations are In-P and K-P interactions.

The self-hosting structure of beta-Ta.

Using electrodeposition from a bath of molten fluorides, single crystals of tetragonal beta-tantalum have been obtained for the first time at normal pressure. The unit-cell parameters are a = 10.211 (3), c = 5.

A novel perovskite-like Ta-bronze KTa1+zO3: preparation, stoichiometry, conductivity and crystal structure studies.

A new cubic Ta-bronze (1) KTa(1+z)(+(5-delta))O(3) [z approximately 0.107 (3)] was obtained on a cathode by molten salt electrolysis of the system K(2)TaOF(5)-K(3)TaO(2)F(4)-(KF + NaF + LiF)(eutectic). Black, metallic cubic crystals of (1) are formed together with tetragonal beta-Ta.