Capillary rheometry is combined with small-angle neutron scattering to simultaneously measure the viscosity and nanostructure of complex fluids containing proteins, surfactants, polymers, and inorganic nanoparticles at shear rates up to 106 s−1.

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The discovery of new low-dimensional transition-metal chalcogenides is contributing to the already prosperous family of these materials. In this study, needleshaped single crystals of a quasi-one-dimensional (1D) material, (Nb 4 Se 15 I 2 )I 2 , were grown by chemical vapor transport, and the structure was solved by single-crystal X-ray diffraction (XRD). The structure has 1D (Nb 4 Se 15 I 2 ) n chains along the [101] direction, with two I − ions per formula unit directly bonded to Nb 5+ . The other two I − ions are loosely coordinated and intercalated between the chains. Individual chains are chiral and stack along the b axis in opposing directions, giving space group P2 1 /c. The phase purity and crystal structure were verified by powder XRD. Density functional theory calculations show (Nb 4 Se 15 I 2 )I 2 to be a semiconductor with a direct band gap of around 0.6 eV. Resistivity measurements of bulk crystals and micropatterned devices demonstrate that (Nb 4 Se 15 I 2 )I 2 has an activation energy of around 0.1 eV, and no anomaly or transition was seen upon cooling. Low-temperature XRD shows that (Nb 4 Se 15 I 2 )I 2 does not undergo a structural phase transformation from room temperature to 8.2 K, unlike related compounds (NbSe 4 ) n I (n = 2, 3, or 3.33), which all exhibit charge-density waves. This compound represents a well-characterized and valenceprecise member of a diverse family of anisotropic transition-metal chalcogenides.

Single crystals of rhombohedral KBiS 2 were synthesized for the first time, and the structure, growth habit, and properties of this layered semiconductor are presented. The single crystals form from a reactive K 2 S 5 salt flux and are still embedded in the residual flux, without removal from the reaction vessel throughout the whole study. Laboratory diffraction contrast tomography (LabDCT) was used to identify the crystalline phase, orientation, and microstructure of the crystals. Meanwhile, powder and single-crystal X-ray diffraction were used to determine detailed crystallographic information. The morphology of the crystalline assemblies observed by absorption contrast tomography reveals screw-dislocation-driven growth to be the dominant mechanism. First-principles electronic structure simulations predict rhombohedral KBiS 2 to be a semiconductor with an indirect band gap, which was confirmed by experiment. This study demonstrates how nondestructive tomographic imaging and 3D crystallography methods can lead to advances in discovering new materials and studying crystal growth mechanisms.