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Li 3 Y 1- x In x Cl 6 undergoes a phase transition from trigonal to monoclinic via an intermediate orthorhombic phase. Although the trigonal yttrium containing the end member phase, Li 3 YCl 6 , synthesized by a mechanochemical route, is known to exhibit stacking fault disorder, not much is known about the monoclinic phases of the serial composition Li 3 Y 1- x In x Cl 6 . This work aims to shed light on the influence of the indium substitution on the phase evolution, along with the evolution of stacking fault disorder using X-ray and neutron powder diffraction together with solid-state nuclear magnetic resonance spectroscopy, studying the lithium-ion diffusion. Although Li 3 Y 1- x In x Cl 6 with x ≤ 0.1 exhibits an ordered trigonal structure like Li 3 YCl 6 , a large degree of stacking fault disorder is observed in the monoclinic phases for the x ≥ 0.3 compositions. The stacking fault disorder materializes as a crystallographic intergrowth of faultless domains with staggered layers stacked in a uniform layer stacking, along with faulted domains with randomized staggered layer stacking. This work shows how structurally complex even the "simple" series of solid solutions can be in this class of halide-based lithium-ion conductors, as apparent from difficulties in finding a consistent structural descriptor for the ionic transport.

The structure of the first lithium-containing bismuth ortho ( o )-thiophosphate was determined using a combination of powder X-ray, neutron, and electron diffraction. Li 60-3 x Bi 16+ x (PS 4 ) 36 with x in the range of 4.1-6.5 possesses a complex monoclinic structure [space group C 2/ c (No. 15)] and a large unit cell with the lattice parameters a = 15.4866 Å, b = 10.3232 Å, c = 33.8046 Å, and β = 85.395° for Li 44.4 Bi 21.2 (PS 4 ) 36 , in agreement with the structure as observed by X-ray and neutron pair distribution function analysis. The disordered distribution of lithium ions within the interstices of the dense host structure and the Li ion dynamics and diffusion pathways have been investigated by solid-state nuclear magnetic resonance (NMR) spectroscopy, pulsed field gradient NMR diffusion measurements, and bond valence sum calculations. The total lithium ion conductivities range from 2.6 × 10 -7 to 2.8 × 10 -6  S cm -1 at 20 °C with activation energies between 0.29 and 0.32 eV, depending on the bismuth content. Despite the highly disordered nature of lithium ions in Li 60-3 x Bi 16+ x (PS 4 ) 36 , the underlying dense host framework appears to limit the dimensionality of the lithium diffusion pathways and emphasizes once more the necessity of a close inspection of the structure-property relationships in solid electrolytes.

The development of novel, intrinsic two-dimensional (2D) antiferromagnets presents the opportunity to vastly improve the efficiency of spintronic devices and sensors. The strong intrinsic antiferromagnetism and van der Waals layered structure exhibited by the bulk transition-metal oxychlorides provide a convenient system for the synthesis of such materials. In this work, we report the exfoliation of bulk FeOCl into and subsequent characterization of intrinsically antiferromagnetic thin-layer FeOCl nanosheets. The magnetic properties of bulk FeOCl, its lithium intercalate, and its nanosheet pellet are measured to determine the evolution of magnetic properties from the three-dimensional to the quasi-two-dimensional system. This work establishes FeOCl and isostructural compounds as a source for the development of two-dimensional intrinsic antiferromagnets.

Thiophosphate compounds have been studied extensively in the past for their rich structural variations and for a large variety of interesting properties. Here, we report 11 new phases with the composition ALnP 2 S 6 (A = Na, K, Rb, Cs; Ln = lanthanide). These new thiophosphates crystallize in four different structure types, with the space groups Fdd2, P1̅, P2 1 , and P2 1 /c, respectively. All phases are insulating and the calculated band gaps range between 3 eV and 3.5 eV. Magnetic measurements on the compounds with open f-shells show paramagnetic behavior and magnetic moments that match the expected free ion values of the respective lanthanide cations. We present a structural stability phase diagram for the ALnP 2 S 6 family of compounds, which reveals a clear relationship between ionic radii and the preferred crystal structure, as well as stability regions to form ALnP 2 S 6 -type phases.

Five new compounds in the Cu/P/Se phase diagram have been synthesized, and their crystal structures have been determined. The crystal structures of these compounds comprise four previously unreported zero-, one-, and two-dimensional selenidophosphate anions containing low-valent phosphorus. In addition to two new modifications of Cu4P2Se6 featuring the well-known hexaselenidohypodiphosphate(IV) ion, there are three copper selenidophosphates with low-valent P: Cu4P3Se4 contains two different new anions, (i) a monomeric (zero-dimensional) selenidophosphate anion [P2Se4](4-) and (ii) a one-dimensional selenidophosphate anion [Formula: see text], which is related to the well-known gray-Se-like [Formula: see text] Zintl anion. Cu4P4Se3 contains one-dimensional [Formula: see text] polyanions, whereas CuP2Se contains the 2D selenidophosphate [Formula: see text] polyanion. It consists of charge-neutral CuP2Se layers separated by a van der Waals gap which is very rare for a Zintl-type phase. Hence, besides black P, CuP2Se constitutes a new possible source of 2D oxidized phosphorus containing layers for intercalation or exfoliation experiments. Additionally, the electronic structures and some fundamental physical properties of the new compounds are reported. All compounds are semiconducting with indirect band gaps of the orders of around 1 eV. The phases reported here add to the structural diversity of chalcogenido phosphates. The structural variety of this family of compounds may translate into a variety of tunable physical properties.

The mechanism of the solid-solid transformation of NH(4)[N(CN)(2)] into NCN[double bond]C(NH(2))(2), which represents the isolobal analogue of Wöhler's historic conversion of ammonium cyanate into urea, has been investigated by temperature-dependent single-crystal and powder X-ray diffraction, neutron powder diffraction, and Raman and solid-state NMR spectroscopy as well as thermoanalytical measurements. The transformation of the ionic dicyanamide into its molecular isomer upon controlled thermal treatment was found to proceed topochemically in the solid state with little molecular motion, giving rise to a single-crystal to single-crystal transformation which manifests itself by a defined metric relation between the unit cells of the two isomers. The exothermic phase transition is thermally activated and was observed to commence at temperatures > or =80 degrees C. The pronounced temperature dependence of the onset of the transformation may be assessed as an indication for the metastability of ammonium dicyanamide at elevated temperatures. Thermal analyses reveal a decrease in the reaction enthalpy (56-13 kJ mol(-1)) at higher heating rates and an average mass loss of 10% gaseous ammonia. Evidence was found for crucial mechanistic steps of the transformation, which is likely to proceed via proton transfer from the ammonium ion to one of the terminal nitrogen atoms of the anion. The protonation is followed by nucleophilic attack of the in situ generated ammonia at the electrophilic nitrile carbon. The proposed mechanistic pathway is based on the results of combined Raman and solid-state NMR spectroscopic as well as neutron powder diffraction measurements.