CsLnCuS (Ln = La-Nd, Sm-Tb): Synthesis, Crystal Structure, and Magnetic and Optical Properties.

This work reports the preparation of new quaternary sulfides CsLnCuS (Ln = La-Nd, Sm-Tb), their original crystal and electronic structures, and their magnetic properties. The sulfides were prepared using a reactive flux method from mixtures of LnS (EuS), CsS, CuS, and S. They crystallize in a new type of structure (2/ space group) and exhibit a layer-like crystal structure, which is a hybrid of those of the ACeCuS series (A = Cs, K) and that of KCeCuS.

Discovery of a Low Thermal Conductivity Oxide Guided by Probe Structure Prediction and Machine Learning.

We report the aperiodic titanate Ba Y Ti O with a room-temperature thermal conductivity that equals the lowest reported for an oxide. The structure is characterised by discontinuous occupancy modulation of each of the sites and can be considered as a quasicrystal. The resulting localisation of lattice vibrations suppresses phonon transport of heat.

Detection and Crystal Structure of Hydrogenated Bipentacene as an Intermediate in Thermally Induced Pentacene Oligomerization.

6,6',13,13'-Tetrahydro-6,6'-bipentacene (HBP), the intermediate molecule connecting pentacene to previously observed peripentacene and extended pentacene oligomers through the formation of a carbon-carbon bond, is synthesized and crystallographically characterized. Heating pentacene to 300 °C under vacuum for 200 h results in pale golden crystals of HBP and amorphous material containing pentacene oligomers, offering experimental evidence that pentacene preferentially dimerizes at the 6,6'-position. Continued heating of HBP results in co-crystals of 6,13-dihydrogenated pentacene and pentacene and further amorphous pentacene oligomers.

Structure determination and crystal chemistry of large repeat mixed-layer hexaferrites.

Hexaferrites are an important class of magnetic oxides with applications in data storage and electronics. Their crystal structures are highly modular, consisting of Fe- or Ba-rich close-packed blocks that can be stacked in different sequences to form a multitude of unique structures, producing large anisotropic unit cells with lattice parameters typically >100 Å along the stacking axis. This has limited atomic-resolution structure solutions to relatively simple examples such as BaZnFeO, whilst longer stacking sequences have been modelled only in terms of block sequences, with no refinement of individual atomic coordinates or occupancies.

BiOCuSeX (X = Cl, Br): A Three-Anion Homologous Series.

Both layered multiple-anion compounds and homologous series are of interest for their electronic properties, including the ability to tune the properties by changing the nature or number of the layers. Here we expand, using both computational and experimental techniques, a recently reported three-anion material, BiOCuSeCl, to the homologous series BiOCuSeX (X = Cl, Br), composed of parent blocks that are well-studied thermoelectric materials. All of the materials show exceptionally low thermal conductivity (0.

Magnetodielectric Effect in Crystals of the Noncentrosymmetric CaOFeS at Low Temperature.

Single crystals of the stoichiometric iron calcium oxysulfide CaOFeS have been grown by a solid-state reaction. Structural analysis of CaOFeS at room temperature by combining single-crystal X-ray diffraction data and transmission electron microscopy leads to a stoichiometric hexagonal noncentrosymmetric P63mc layered structure isostructural to CaOZnS. It is built from alternating layers made of FeOS3 tetrahedra sharing sulfur apexes and stacked with Ca(2+) planes.

Structural transition at 360 K in the CaFe₅O₇ ferrite: toward a new charge ordering distribution.

An efficient synthesis route is proposed to obtain single phase powder ceramic of CaFe5O7. This complex structure can be described as an intergrowth between one CaFe2O4 unit and n = 3 slices of FeO Wüstite-type structure. A detailed structural study has been carried out at room temperature combining transmission electron microscopy (TEM) observations (ED, HREM), scanning transmission electron microscopy (STEM-HAADF), and X-ray diffraction data.