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Lithium rare earth metal halides have emerged as attractive candidates for solid electrolytes in all-solid-state batteries due to their high ionic conductivities and stability against oxidation. Here, we study their electrochemical properties as a function of the synthesis procedure and post-synthetic treatment and report on the impact of iso- and aliovalent substitutions in the cation and anion sublattices of the lithium rare earth metal iodides Li3MI6. For selected compounds we have investigated the impact of the synthetic approach, i.e. of different solid-state synthesis protocols, and mechanochemical ball-milling without and with post-synthetic calcination on the resulting materials. Lithium rare earth metal iodides obtained from solid-state synthesis generally outperform the mechanochemical synthesized compounds in terms of ionic conductivity and activation energy for ion diffusion, but when mechanochemical ball-milling is combined with a post-synthetic calcination step, these iodides show similar ionic conductivites as their counterparts obtained from conventional solid-state synthesis. Furthermore, we report a series of new Li3MI6 compounds with M = Y, Sm, Gd–Lu, partially Cd2+-substituted Li3+yGd1−yCdyI6 and partially Cd2+-, Ca2+- and Zr4+-substituted Li3±yY1−yM II/IVy Br6−xIx phases. Using a combination of ssNMR, EIS and PFG-NMR we reveal the influence of structural parameters such as RE/Li radius ratio, intra-layer cation and stacking fault disorder on the ionic transport properties, obtained from in-depth PXRD analyses. We find that the ionic conductivity is strongly affected by the ratio of the RE/Li radius ratio as well as by the degree of intra-layer cation disorder. It ranges between 3.0 × 10−5 S cm−1 and 4.6 × 10−4 S cm−1 for M = Lu–Sm at 20 °C with activation energies between 0.20 eV to 0.33 eV. The combination of partial anion and cation substitution increases the ionic conductivity up to 3.0 × 10−3 S cm−1 and leads to a lower activation energy of 0.17 eV. This study highlights the impact of microstructural effects on the electrochemical properties of solid electrolytes. The rational design and modification of solid electrolytes, along with their comprehensive (micro)structural analysis is thus crucial to optimize their ionic transport properties for applications in all-solid-state batteries. [ABSTRACT FROM AUTHOR]

The water-in-salt (WIS) electrolyte represents a newly developed battery electrolyte system with high ionic conductivity that enables cells with a broader electrochemical window and improved cyclability. Several theories have been proposed to explain the co-existence of high conductivity and salt concentration in a WIS model system with lithium bis(trifluoromethanesulfonyl)imide salt — (LiTFSI)–H2O. However, experimental and theoretical studies focused on salt concentrations below 21 mol kg−1. Here, we have systematically measured the physical and electrochemical properties of the LiTFSI–H2O binary system in the salt concentration range from 21–55.5 mol kg−1 in the semi-solid regime. Based on the Raman spectroscopy and lithium transference number results, we propose that the majority of the species formed are neutral or negatively charged ion pairs or clusters in higher aggregation states. The transference number of elemental Li measured by pulsed-field gradient nuclear magnetic resonance (PFG)-NMR remains unexpectedly high (around 0.7) when the mole ratio of Li and H2O reaches 1 : 1. On the other hand, the lithium transference numbers measured by the galvanostatic polarization method for various concentrations are lower than 0.1. We show that charged associates can provide a qualitative explanation for the observed ion transport behavior. We also report the existence of local minima in temperature-dependent conductivity at various concentrations, and details of the phase transition of LiTFSI monohydrate. [ABSTRACT FROM AUTHOR]

In lithium thiocyanate Li(SCN), the temperature regime below the melting point (274 °C) is characterized by excess conductivities over the usual Arrhenius behavior (premelting regime). Here, the Schottky defect pair concentration is high, and the point defect chemistry can no longer be considered as dilute. Coulomb interactions of Schottky pairs are expected to occur lowering the formation energy of new carriers and hence leading avalanche-like to a transition into a fully defective superionic state. The respective non-linear behavior is investigated using the cube-root law approach characterized by a defect interaction parameter J, which is a measure of the effective defect-lattice energy. In the case of Li(SCN), the rather pronounced volume expansion is to be included in the model. A literature comparison with other materials emphasizes to what degree defect formation as well as defect interactions depend not only on the dominant mobile defect, but also on the respective sublattice. Overall, a quantitative description of the defect chemistry of Li(SCN) in the premelting regime is derived. [ABSTRACT FROM AUTHOR]

Specific aspects of the Li+ cation conductivity of anhydrous Li(SCN) are investigated, in particular the high migration enthalpy of lithium vacancies. Close inspection of impedance spectra and conductivity data reveals two bulk relaxation processes, with comparatively fast ion transport at high frequencies and slow ion migration at low frequencies. The impedance results are supported by solid state nuclear magnetic resonance (ssNMR), and pair distribution function (PDF) analysis. This behavior reflects a frequency dependent conductivity, which is related to the extremely slow thiocyanate (SCN)− anion lattice relaxation that occurs when a Li+ cation jumps to the next available site. Two possible migration models are proposed: the first model considers an asymmetric energy landscape for Li+ cation hopping, while the second model is connected to the jump relaxation model and allows for 180° rotational disorder of the (SCN)− anion. A complete kinetic analysis for the hopping of Li+ cations is presented, which reveals new fundamental insights into the ion transport mechanism of materials with complex anions. [ABSTRACT FROM AUTHOR]

This work reports on the ion transport properties and defect chemistry in anhydrous lithium thiocyanate Li(SCN), which is a pseudo-halide Li+ cation conductor. An extensive doping study was conducted, employing magnesium, zinc and cobalt thiocyanate as donor dopants to systematically vary the conductivity and derive a defect model. The investigations are based on impedance measurements and supported by other analytical techniques such as X-ray powder diffraction (XRPD), infrared (IR) spectroscopy, and density functional theory (DFT) calculations. The material was identified as Schottky disordered with lithium vacancies being the majority mobile charge carriers. In the case of Mg2+ as dopant, defect association with lithium vacancies was observed at low temperatures. Despite a comparably low Schottky defect formation enthalpy of (0.6 ± 0.3) eV, the unexpectedly high lithium vacancy migration enthalpy of (0.89 ± 0.08) eV distinguishes Li(SCN) from the chemically related lithium halides. A detailed defect model of Li(SCN) is presented and respective thermodynamic and kinetic data are given. The thiocyanate anion (SCN)− has a significant impact on ion mobility due to its anisotropic structure and bifunctionality in forming both Li–N and Li–S bonds. More details about the impact on ion dynamics at local and global scale, and on the defect chemical analysis of the premelting regime at high temperatures are given in separate publications (Part II and Part III). [ABSTRACT FROM AUTHOR]

We demonstrate the ability to controllably desolvate a crystal-solvate system in a step-wise fashion through polymer-assisted grinding by varying the type and proportion of polymer agent used. A plausible mechanistic explanation is proposed based on a combination of experimental evidence and computational analysis. Specifically, Raman spectroscopy, total scattering pair distribution function analysis and computed reaction energies suggest that the desolvation process is associated with preferred interactions between the solvent molecules and specific polymers. This approach could potentially be extended to any type of material, including heat-sensitive materials, where classical desolvation by thermal processes is not possible, and provides an additional route for formulation processing. [ABSTRACT FROM AUTHOR]

Li[SCN]·THF and Li[SCN]·2THF can be obtained from solutions of anhydrous Li[SCN] in tetrahydrofuran (C4H8O, THF). Both compounds are very hygroscopic and slowly decompose even at room temperature. At ambient conditions Li[SCN]·THF crystallizes in the monoclinic space group P21/c with the lattice parameters a = 574.41(2), b = 1643.11(6), c = 830.15(3) pm and β = 99.009(1)° for Z = 4 as determined by laboratory X-ray powder diffraction. Its crystal structure contains Li+ cations surrounded by one THF molecule and three thiocyanate anions [SCN]− forming {Li[NCS]2[SCN](OC4H8)}2− tetrahedra, which join together as pairs via shared N⋯N edges. CHNS combustion analysis and vibrational spectroscopy confirmed its composition, whereas differential scanning calorimetry and thermogravimetric analysis coupled with a mass spectrometer were applied to record its thermal behaviour. Li[SCN]·2THF crystallises in a primitive monoclinic lattice as well, but in the space group P21/n with the lattice parameters a = 1132.73(3), b = 1637.98(3), c = 1264.88(2) pm and β = 94.393(2)° for Z = 8 as determined from single-crystal X-ray diffraction data at 100 K. Its structure contains two crystallographically independent Li+-centred tetrahedra {Li[NCS]2(OC4H8)2}−, which form dimers {(C4H8O)2Li[μ2-NCS]2Li(OC4H8)2} via shared N⋯N edges. They are merely stabilised by weak agostic H⋯S interactions between some CH2-groups of the C4H8O molecules and the [NCS]− ligands. [ABSTRACT FROM AUTHOR]

Mg(SCN)2·4H2O can be converted into previously unknown compounds Mg(SCN)2·(4 − x) H2O·xTHF with x = 0, 2 and 4 by multiple recrystallization in tetrahydrofuran (THF). The phases were characterized by infrared spectroscopy (IR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), and their crystal structures were solved from X-ray powder diffraction (XRPD) data. In the crystal structures isolated Mg(NCS)2(H2O)4−x(THF)x units form layered motifs. The thermal behavior of Mg(SCN)2·4H2O and Mg(SCN)2·4THF was investigated by temperature dependent in situ XRPD, where Mg(SCN)2·4THF was found to acquire a room temperature (α-form) and high temperature modification (β-form). The phase transformation is associated with an order–disorder transition of the THF molecules and with a reversion of the stacking order of the layered motifs. Further heating eventually leads to the formation of Mg(SCN)2·2THF. There thiocyanate related sulfur atoms fill the voids in the coordination sphere of magnesium, which leads to the formation of one dimensional electroneutral ∞[Mg(NCS)2/2(SCN)2/2(THF)2] chains. All investigated Mg(SCN)2·(4 − x) H2O·xTHF phases exhibit a remarkable anisotropic thermal expansion, and Mg(SCN)2·4H2O and Mg(SCN)2·2THF were found to show both positive and negative thermal expansion coefficients. [ABSTRACT FROM AUTHOR]

The solid state assembly of two cyclic hexapeptoids decorated respectively with five and six carbon N-alkyl side chains is analyzed by single crystal X-ray diffraction, intermolecular energies and lattice energy calculations. Thermal analysis and variable temperature X-ray powder diffraction were also carried out to analyze their thermal behaviour. The crystal structures of the two compounds feature architectural similarities, but also small relevant differences due to side chains-to-side chains interactions, which can explain the observed differences in the thermal properties. The compound with N-pentyl side chains exhibits a phase transition upon cooling down from room temperature to 100 K, while that with N-hexyl side chains features no phase transformation on cooling, instead a phase transformation occurs at 335 K upon heating. [ABSTRACT FROM AUTHOR]

Time-resolved mechanochemical cocrystallisation studies have so-far focused solely on neat and liquid-assisted grinding. Here, we report the investigation of polymer-assisted grinding reactions using in situ X-ray powder diffraction, revealing that reaction rate is almost double compared to neat grinding and independent of the molecular weight and amount of the polymer additive used. [ABSTRACT FROM AUTHOR]

The reaction of Ni(NCS)2 with 3-ethylpyridine in water leads to the formation of two known modifications of Ni(NCS)2(3-ethylpyridine)4 (1-I and 1-II) as well as of Ni(NCS)2(3-ethylpyridine)2(H2O)2 (2) that consist of discrete complexes. If the synthesis is performed in ethyl acetate, the new compound [Ni(NCS)2(3-ethylpyridine)2]n (3-lc) formed that comprises linear and corrugated Ni(NCS)2 chains in one crystal. By changing the solvent to dichloromethane, a solvate of compound 3 is obtained that consists exclusively of corrugated chains (3c-CH2Cl2). 3c-CH2Cl2 is unstable and transforms immediately into 3-lc. Upon heating the precursor complexes 1-I, 1-II and 2, the 3-ethylpyridine ligands are removed in two steps leading to a mixture of 3-lc and an additional isomer of 3 (3-l) in the first step that decomposes upon further heating into a compound with the composition [Ni(NCS)2(3-ethylpyridine)]n (4). Ex and in situ XRPD measurements reveal that a mixture of two modifications (4-I and 4-II) is always formed, preventing their structure determination by XRPD. Time dependent investigations in solution prove that 3-l is formed under kinetic control and transforms into 3-lc within several hours that is thermodynamically stable at room-temperature. Structure analysis of 3-l shows that in contrast to 3-lc and 3c-CH2Cl2 this isomer consists exclusively of linear Ni(NCS)2 chains. Magnetic measurements of the new chain compounds 3-l and 3-lc shows χT values that are typical for Ni(II) cations with S = 1. For 3-l the exchange constant was determined by fitting of the magnetic data leading to a value that is similar to that of [Ni(NSC)2(2,2′-bipyridine)2]n. [ABSTRACT FROM AUTHOR]

Apatite-type silicates Y7.75Dy0.25Ca2(SiO4)6O2 and Dy8Ca2(SiO4)6O2 were prepared by high-temperature solid state synthesis. In the crystal lattice, Dy3+ partially substitutes Ca2+, preferably at the 6h Ca2-site, and forms a short bond of 2.2 Å with the intra-channel O2−. The imposed strong ligand field anisotropy provides large magnetic anisotropy, which manifests itself as slow relaxation of magnetization at low temperatures. The magnetic dynamics is characterized by three or two characteristic values of relaxation time, respectively, which may be attributed to a single Dy3+ center. A phenomenological model is proposed which explains this response in terms of single paramagnetic center multiple relaxation. [ABSTRACT FROM AUTHOR]

The reaction of Fe(NCS)2 with 4-picoline in solution leads to two new discrete complexes, Fe(NCS)2(4-picoline)4·solvate (1-Fe) and Fe(NCS)2(4-picoline)2(H2O)2 (2-Fe–H2O). Upon heating, both compounds transform into two isomers with the composition [Fe(NCS)2(4-picoline)2]n (2-Fe/I and 2-Fe/II) that consist of chains and that are related by monotropy, with 2-Fe/I as the thermodynamically stable form. Upon further heating, a transformation into a more condensed chain compound of unusual structure with the composition [Fe(NCS)2(4-picoline)]n (3-Fe) is observed. The crystal structures of 2-Fe/I and 2-Fe/II were determined by Rietveld refinements, as it was found that 2-Fe/I is isotypic to the corresponding Cd compound 2-Cd/I, whereas 2-Fe/II is isotypic to [Cu(NCS)2(4-cyanopyridine)2]n which was reported recently. To retrieve structural information on 3-Fe the corresponding Cd compound (3-Cd) was synthesized and was shown to be isotypic to 3-Fe. Finally, upon heating the already known compounds [Cd(NCS)2(4-picoline)4]·0.67·4-picoline·0.33·H2O solvate (1-Cd) and [Cd(NCS)2(4-picoline)2]n (2-Cd/I) a new thermodynamically metastable modification was found (2-Cd/III) that is isotypic to [Cd(NCS)2(4-cyanopyridine)2]n and behaves monotropically to 2-Cd/I with the latter as the thermodynamically stable phase. [ABSTRACT FROM AUTHOR]

During the systematic investigation of the ternary system Ca(CH3COO)2–Ca(HCOO)2–H2O at room temperature, the congruent crystallisation of two solid calcium acetate formates was observed: the hitherto unknown Ca3(CH3COO)4(HCOO)2·4H2O and the poorly characterised Ca(CH3COO)(HCOO)·H2O. The latter is a frequently observed efflorescence phase found on calcareous objects and it could be also identified as a corrosion phase in a natural history collection of birds' eggs. Elemental and thermal analyses were employed to determine the phase compositions and by Raman and IR spectroscopy the presence of acetate and formate anions in both solids was confirmed. Laboratory X-ray powder diffraction data were used to solve the crystal structures. Ca3(CH3COO)4(HCOO)2·4H2O crystallises in a primitive tetragonal unit cell with space group P41212 and lattice parameters of a = 6.8655(1) Å and c = 45.5454(6) Å, while Ca(CH3COO)(HCOO)·H2O crystallises in a primitive monoclinic unit cell with space group P21/c and lattice parameters of a = 9.2729(1) Å, b = 6.8002(1) Å, c = 11.2219(2) Å and β = 121.232(1)°. Calcium carboxylate zig-zag chains [Ca(μ2-RCOO)+]n (R = CH3 or H) are the main motif of both crystal structures. In Ca3(CH3COO)4(HCOO)2·4H2O these chains are exclusively composed of acetate anions, whereas in Ca(CH3COO)(HCOO)·H2O only formate anions are situated in the chains. The remaining places in the 7–8 fold coordination sphere of the calcium cations are filled by water molecules and additional carboxylate anions that interconnect neighbouring chains, which eventually leads to layered motifs in both structures. [ABSTRACT FROM AUTHOR]

Powder samples of Ag3LiIr2O6 and Ag3LiRu2O6 were synthesized from α-Li2IrO3 and Li2RuO3 respectively by ion exchange in an AgNO3 melt. The crystal structures of the title compounds were solved from high resolution laboratory X-ray powder diffraction (XRPD) patterns and from pair distribution function (PDF) analysis using synchrotron X-ray powder diffraction data. In both crystal structures edge sharing LiO6/3- and (Ir/Ru)O6/3-octahedra form honeycomb like layers that are stacked in a staggered fashion. Silver cations, situated in-between the layers mediate the interlayer interactions by linear O–Ag–O bonds. Anisotropic peak broadening in the XRPD patterns and diffuse scattering occurring as streaks in the precession electron diffraction (PED) patterns indicate the presence of stacking faults, which could be also visualized by high resolution transmission electron microscopy (HRTEM). Possible alternative stacking sequences were derived from the ideal crystal and incorporated into a microstructure model. By applying a supercell approach that randomly generates and averages stacking sequences based on transition probabilities and combining it with a grid search algorithm, the microstructures, i.e. the degrees of faulting in the structures of the title compounds were refined to the measured XRPD data. In result the crystal structures of Ag3LiIr2O6 and Ag3LiRu2O6 were found to be vastly faulted with almost no coherence of the stacked layers. [ABSTRACT FROM AUTHOR]

Long-term crystallisation from aqueous copper(ii)–acetate solution after the addition of ammonia at 25 °C led to the formation of a hitherto poorly characterised phase in the verdigris pigment system Cu(CH3COO)2–Cu(OH)2–H2O. Laboratory X-ray powder diffraction (XRPD) was successfully employed to solve the crystal structure. The structure solution reveals a phase composition of the Cu3(CH3COO)4(OH)2·5H2O ≡ 2-1-5 phase, which was also confirmed by thermal analysis. The 2-1-5 phase crystallises in space group P21/c (14) with lattice parameters of a = 12.4835(2) Å, b = 14.4246(2) Å, c = 10.7333(1) Å and β = 102.871(1)°. The crystal structure consists of Cu2(CH3COO)2(CH3COO)1/2(OH)4/3H2O1/6+ dimers that are interconnected by Cu(CH3COO)(CH3COO)1/2(OH)2/31/6− squares forming chains running in the c-direction. Non-coordinating hydrate water molecules are intercalated inbetween the chains and mediate the inter-chain interaction. IR and Raman spectroscopy techniques were also employed to confirm selected aspects of the determined crystal structure. The magnetic properties of the 2-1-5 phase decompose into two independent subsystems: a strongly antiferromagnetically spin exchange coupled magnetic Cu–Cu dimer and a significantly weaker coupled Cu monomer. The light blue colour of the sample originates from a reflectance maximum at 488 nm and significantly differs from the known verdigris phases. An investigation of several historic verdigris pigment samples revealed that this phase occurs both as a minor and a major component. Hence, our reference data for the title compound will help to improve the understanding of the multiphase mixtures occurring in historic verdigris samples. [ABSTRACT FROM AUTHOR]

The use of a dodecanuclear zirconium acetate cluster as a precursor enables the rapid, clean mechanochemical synthesis of high-microporosity metal–organic frameworks NU-901 and UiO-67, with surface areas up to 2250 m2 g−1. Real-time X-ray diffraction monitoring reveals that mechanochemical reactions involving the conventional hexanuclear zirconium methacrylate precursor are hindered by the formation of an inert intermediate, which does not appear when using the dodecanuclear acetate cluster as a reactant. [ABSTRACT FROM AUTHOR]

We demonstrate that the simultaneous substitution of calcium and aluminum for strontium and iron in strontium hexaferrite results in a significant increase of coercivity up to a record high of 21.3 kOe. We propose that the effect is originated from a crystal structure distortion causing an increase of the magnetocrystalline anisotropy. [ABSTRACT FROM AUTHOR]

A powder sample of pure H3LiIr2O6 was synthesized from α-Li2IrO3 powder by a soft chemical replacement of Li+ with H+. The crystal structure of H3LiIr2O6 consists of sheets of edge sharing LiO6- and IrO6-octahedra forming a honeycomb network with layers stacked in a monoclinic distorted HCrO2 type pattern. Heavy stacking faulting of the sheets is indicated by anisotropic peak broadening in the X-ray powder diffraction (XRPD) pattern. The ideal, faultless crystal structure was obtained by a Rietveld refinement of the laboratory XRPD pattern while using the LiIr2O63−-layers of α-Li2IrO3 as a starting model. The low radial distances of the PDF function, derived from synchrotron XRPD data, as constraints to stabilize the structural refinement. DIFFaX-simulations, structural considerations, high radial distances of the PDF function and a Rietveld compatible global optimization of a supercell were employed to derive a suitable faulting model and to refine the microstructure using the experimental data. We assumed that the overall stacking pattern of the layers in the structure of H3LiIr2O6 is governed by interlayer O–H…O contacts. From the constitution of the layers, different stacking patterns with similar amounts of strong O–H…O contacts are considered. Random transitions among these stacking patterns can occur as faults in the crystal structure of H3LiIr2O6, which quantitatively describe the observed XRPD. [ABSTRACT FROM AUTHOR]

Known synthesis approaches for basic copper(ii) acetates, the main components of historic verdrigis pigments were reinvestigated and revealed to be partially irreproducible. A modification of the reaction conditions led to the successful and reproducible synthesis of the 1–2–0 phase (Cu3(CH3COO)2(OH)4 = 1Cu(CH3COO)2·2Cu(OH)2·0H2O). The phase composition was derived from elemental and thermal analysis and confirmed by the crystal structure solution using synchrotron X-ray powder diffraction (XRPD) data. The 1–2–0 phase crystallises in space group Pbca with lattice parameters of a = 20.9742(1) Å, b = 7.2076(1) Å, and c = 13.1220(1) Å. The crystal structure consists of Cu2(CH3-COO)2(OH)4/3(OH)2/21/3− dimers, which are interconnected by corner sharing Cu(OH)2/3(OH)2/21/3+ squares forming layers perpendicular to the a-axis. The deep blue color of the solid originates from a reflectance maximum at 472 nm and from an absorbance maximum at 676 nm that is comparable with other historic blue pigments like azurite or Egyptian blue. IR- and Raman-spectroscopic properties of the solid were investigated as well, which demonstrated that the obtained product is identical with a previously synthesised verdigris phase that was obtained by applying historical procedures. Therefore, our reference data for the title compound will help to improve the understanding of the multiphase mixtures occurring in historic verdigris samples. The magnetic properties of the 1–2–0 phase were also investigated. At low temperatures the magnetic susceptibility is well described by a spin-1/2 Heisenberg chain with uniform antiferromagnetic nearest-neighbour spin exchange coupling of only one of three Cu magnetic moments. Due to the very strong antiferromagnetic coupling of the Cu2(CH3-COO)2(OH)4/3(OH)2/21/3− dimers their contribution to magnetism becomes relevant above ∼140 K, which results in the presence of two distinct temperature regions where Curie–Weiss behaviour of the magnetic susceptibility with different Curie constants and Weiss temperatures is found. [ABSTRACT FROM AUTHOR]

Reaction of cobalt(ii) and nickel(ii) thiocyanate with ethylisonicotinate leads to the formation of [M(NCS)2(ethylisonicotinate)2]n with M = Co (2-Co) and M = Ni (2-Ni), which can also be obtained by thermal decomposition of M(NCS)2(ethylisonicotinate)4 (M = Co (1-Co), Ni (1-Ni)). The crystal structure of 2-Ni was determined by single crystal X-ray diffraction. The Ni(ii) cations are octahedrally coordinated by two N and two S bonding thiocyanate anions and two ethylisonicotinate ligands and are linked by pairs of anionic ligands into dimers, that are connected into layers by single thiocyanate bridges. The crystal structure of 2-Co was refined by Rietveld analysis and is isostructural to 2-Ni. For both compounds ferromagnetic ordering is observed at 8.7 K (2-Ni) and at 1.72 K (2-Co), which was also confirmed by specific heat measurements. Similar measurements on [Co(NCS)2(4-acetylpyridine)2]n that exhibits the same layer topology also prove magnetic ordering at 1.33 K. Constrained DFT calculations (CDFT) support the ferromagnetic interactions within the layers. The calculated exchange constants in 2-Ni were used to simulate the susceptibility by quantum Monte Carlo method. The single-ion magnetic anisotropy of the metal ions has been investigated by CASSCF/CASPT2 calculations indicating significant differences between 2-Ni and 2-Co. [ABSTRACT FROM AUTHOR]

The primary adsorption sites for Kr and Xe within the large-pore metal-organic framework CuI-MFU-4i have been investigated by high-resolution synchrotron powder diffraction, revealing an enormous number of adsorption sites: in total, 10 crystallographically different positions for Xe and 8 positions for Kr were localized, the first five of which are located near metal atoms and the organic linker, and the remaining sites form a second adsorption layer in the pores. [ABSTRACT FROM AUTHOR]

An experimental technique for in situ and real-time monitoring of mechanochemical reactions in a shaker ball mill was recently described, which utilises highly penetrating X-ray radiation available at the ID15B beamline of the European Synchrotron Radiation Facility. Herein, we describe the first attempts to perform such reaction monitoring in a quantitative fashion, by introducing an internal X-ray diffraction standard. The use of silicon as an internal standard resolved the issue with variations of the amount of the sample in the X-ray beam due to the non-uniform distribution of the sample in the reaction jar and allowed, via Rietveld analysis, the first quantitative estimate of the amorphous phase content in a mechanochemical reaction as it is being milled. We also highlight problems associated with the non-ideal mixing of the reaction mixture. [ABSTRACT FROM AUTHOR]

Codeine phosphate forms three hydrates and two anhydrates. The sesquihydrate and hemihydrate, which differ by one water molecule, are stable at room temperature. The influence of this molecule on the internal crystal structure and how it translates into the external crystal shape are reported. [ABSTRACT FROM AUTHOR]

A bicyclobutyl that bears six carboxylic acid groups results from a trimerisation of a diene diacid in the solid state. Powder X-ray diffraction and a co-crystallisation are used to solve the structure of the diene and elucidate the stereochemistry of the bicyclobutyl, respectively. [ABSTRACT FROM AUTHOR]

A layered cobalt phosphonate, Co(2-pmp)(H2O)2 (1) (2-pmpH2 = 2-pyridylmethylphosphonic acid) is reported, which provides the first example of metamagnetic cobalt system that shows reversible changes in both structures and magnetic behaviors upon dehydration-hydration process. [ABSTRACT FROM AUTHOR]

A layered cobalt phosphonate, Co(2-pmp)(H2O)2(1) (2-pmpH2= 2-pyridylmethylphosphonic acid) is reported, which provides the first example of metamagnetic cobalt system that shows reversible changes in both structures and magnetic behaviors upon dehydration-hydration process. [ABSTRACT FROM AUTHOR]

Powder samples of Ag3LiIr2O6 and Ag3LiRu2O6 were synthesized from α-Li2IrO3 and Li2RuO3 respectively by ion exchange in an AgNO3 melt. The crystal structures of the title compounds were solved from high resolution laboratory X-ray powder diffraction (XRPD) patterns and from pair distribution function (PDF) analysis using synchrotron X-ray powder diffraction data. In both crystal structures edge sharing LiO6/3- and (Ir/Ru)O6/3-octahedra form honeycomb like layers that are stacked in a staggered fashion. Silver cations, situated in-between the layers mediate the interlayer interactions by linear O–Ag–O bonds. Anisotropic peak broadening in the XRPD patterns and diffuse scattering occurring as streaks in the precession electron diffraction (PED) patterns indicate the presence of stacking faults, which could be also visualized by high resolution transmission electron microscopy (HRTEM). Possible alternative stacking sequences were derived from the ideal crystal and incorporated into a microstructure model. By applying a supercell approach that randomly generates and averages stacking sequences based on transition probabilities and combining it with a grid search algorithm, the microstructures, i.e. the degrees of faulting in the structures of the title compounds were refined to the measured XRPD data. In result the crystal structures of Ag3LiIr2O6 and Ag3LiRu2O6 were found to be vastly faulted with almost no coherence of the stacked layers. [ABSTRACT FROM AUTHOR]

A powder sample of pure H3LiIr2O6 was synthesized from α-Li2IrO3 powder by a soft chemical replacement of Li+ with H+. The crystal structure of H3LiIr2O6 consists of sheets of edge sharing LiO6- and IrO6-octahedra forming a honeycomb network with layers stacked in a monoclinic distorted HCrO2 type pattern. Heavy stacking faulting of the sheets is indicated by anisotropic peak broadening in the X-ray powder diffraction (XRPD) pattern. The ideal, faultless crystal structure was obtained by a Rietveld refinement of the laboratory XRPD pattern while using the LiIr2O63−-layers of α-Li2IrO3 as a starting model. The low radial distances of the PDF function, derived from synchrotron XRPD data, as constraints to stabilize the structural refinement. DIFFaX-simulations, structural considerations, high radial distances of the PDF function and a Rietveld compatible global optimization of a supercell were employed to derive a suitable faulting model and to refine the microstructure using the experimental data. We assumed that the overall stacking pattern of the layers in the structure of H3LiIr2O6 is governed by interlayer O–H…O contacts. From the constitution of the layers, different stacking patterns with similar amounts of strong O–H…O contacts are considered. Random transitions among these stacking patterns can occur as faults in the crystal structure of H3LiIr2O6, which quantitatively describe the observed XRPD. [ABSTRACT FROM AUTHOR]

Known synthesis approaches for basic copper(ii) acetates, the main components of historic verdrigis pigments were reinvestigated and revealed to be partially irreproducible. A modification of the reaction conditions led to the successful and reproducible synthesis of the 1–2–0 phase (Cu3(CH3COO)2(OH)4 = 1Cu(CH3COO)2·2Cu(OH)2·0H2O). The phase composition was derived from elemental and thermal analysis and confirmed by the crystal structure solution using synchrotron X-ray powder diffraction (XRPD) data. The 1–2–0 phase crystallises in space group Pbca with lattice parameters of a = 20.9742(1) Å, b = 7.2076(1) Å, and c = 13.1220(1) Å. The crystal structure consists of Cu2(CH3-COO)2(OH)4/3(OH)2/21/3− dimers, which are interconnected by corner sharing Cu(OH)2/3(OH)2/21/3+ squares forming layers perpendicular to the a-axis. The deep blue color of the solid originates from a reflectance maximum at 472 nm and from an absorbance maximum at 676 nm that is comparable with other historic blue pigments like azurite or Egyptian blue. IR- and Raman-spectroscopic properties of the solid were investigated as well, which demonstrated that the obtained product is identical with a previously synthesised verdigris phase that was obtained by applying historical procedures. Therefore, our reference data for the title compound will help to improve the understanding of the multiphase mixtures occurring in historic verdigris samples. The magnetic properties of the 1–2–0 phase were also investigated. At low temperatures the magnetic susceptibility is well described by a spin-1/2 Heisenberg chain with uniform antiferromagnetic nearest-neighbour spin exchange coupling of only one of three Cu magnetic moments. Due to the very strong antiferromagnetic coupling of the Cu2(CH3-COO)2(OH)4/3(OH)2/21/3− dimers their contribution to magnetism becomes relevant above ∼140 K, which results in the presence of two distinct temperature regions where Curie–Weiss behaviour of the magnetic susceptibility with different Curie constants and Weiss temperatures is found. [ABSTRACT FROM AUTHOR]

Li[SCN]·THF and Li[SCN]·2THF can be obtained from solutions of anhydrous Li[SCN] in tetrahydrofuran (C 4 H 8 O, THF). Both compounds are very hygroscopic and slowly decompose even at room temperature. At ambient conditions Li[SCN]·THF crystallizes in the monoclinic space group P 2 1 / c with the lattice parameters a = 574.41(2), b = 1643.11(6), c = 830.15(3) pm and β = 99.009(1)° for Z = 4 as determined by laboratory X-ray powder diffraction. Its crystal structure contains Li + cations surrounded by one THF molecule and three thiocyanate anions [SCN] - forming {Li[NCS] 2 [SCN](OC 4 H 8 )} 2- tetrahedra, which join together as pairs via shared N⋯N edges. CHNS combustion analysis and vibrational spectroscopy confirmed its composition, whereas differential scanning calorimetry and thermogravimetric analysis coupled with a mass spectrometer were applied to record its thermal behaviour. Li[SCN]·2THF crystallises in a primitive monoclinic lattice as well, but in the space group P 2 1 / n with the lattice parameters a = 1132.73(3), b = 1637.98(3), c = 1264.88(2) pm and β = 94.393(2)° for Z = 8 as determined from single-crystal X-ray diffraction data at 100 K. Its structure contains two crystallographically independent Li + -centred tetrahedra {Li[NCS] 2 (OC 4 H 8 ) 2 } - , which form dimers {(C 4 H 8 O) 2 Li[μ 2 -NCS] 2 Li(OC 4 H 8 ) 2 } via shared N⋯N edges. They are merely stabilised by weak agostic H⋯S interactions between some CH 2 -groups of the C 4 H 8 O molecules and the [NCS] - ligands.

Mg(SCN)2·4H2O can be converted into previously unknown compounds Mg(SCN)2·(4 - x) H2O·xTHF with x = 0, 2 and 4 by multiple recrystallization in tetrahydrofuran (THF). The phases were characterized by infrared spectroscopy (IR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), and their crystal structures were solved from X-ray powder diffraction (XRPD) data. In the crystal structures isolated Mg(NCS)2(H2O)4-x(THF)x units form layered motifs. The thermal behavior of Mg(SCN)2·4H2O and Mg(SCN)2·4THF was investigated by temperature dependent in situ XRPD, where Mg(SCN)2·4THF was found to acquire a room temperature (α-form) and high temperature modification (β-form). The phase transformation is associated with an order-disorder transition of the THF molecules and with a reversion of the stacking order of the layered motifs. Further heating eventually leads to the formation of Mg(SCN)2·2THF. There thiocyanate related sulfur atoms fill the voids in the coordination sphere of magnesium, which leads to the formation of one dimensional electroneutral ∞[Mg(NCS)2/2(SCN)2/2(THF)2] chains. All investigated Mg(SCN)2·(4 - x) H2O·xTHF phases exhibit a remarkable anisotropic thermal expansion, and Mg(SCN)2·4H2O and Mg(SCN)2·2THF were found to show both positive and negative thermal expansion coefficients.

Tb-diluted and Tb-rich apatite-type silicates with compositions Y 7.75 Tb 0.25 Ca 2 (SiO 4 ) 6 O 2 and Tb 8 Ca 2 (SiO 4 ) 6 O 2 , respectively, exhibit field induced multiple slow relaxation of magnetization. The former reveals two slow relaxation paths, the latter only one with a longer relaxation time of several seconds. The relaxation features of the Tb-diluted one are comparable with those of analogue compounds, where Tb is replaced by Dy, as well as with those of a Tb-doped calcium phosphate apatite. The relaxation parameters of the Tb-rich compound virtually match those of the Dy-based analogue Dy 8 Ca 2 (SiO 4 ) 6 O 2 . The latter represents the first instance of independence of magnetization relaxation on the nature of a paramagnetic rare-earth metal ion in single ion magnet like materials., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Apatite-type silicates Y7.75Dy0.25Ca2(SiO4)6O2 and Dy8Ca2(SiO4)6O2 were prepared by high-temperature solid state synthesis. In the crystal lattice, Dy3+ partially substitutes Ca2+, preferably at the 6h Ca2-site, and forms a short bond of 2.2 Å with the intra-channel O2-. The imposed strong ligand field anisotropy provides large magnetic anisotropy, which manifests itself as slow relaxation of magnetization at low temperatures. The magnetic dynamics is characterized by three or two characteristic values of relaxation time, respectively, which may be attributed to a single Dy3+ center. A phenomenological model is proposed which explains this response in terms of single paramagnetic center multiple relaxation.

During the systematic investigation of the ternary system Ca(CH 3 COO) 2 -Ca(HCOO) 2 -H 2 O at room temperature, the congruent crystallisation of two solid calcium acetate formates was observed: the hitherto unknown Ca 3 (CH 3 COO) 4 (HCOO) 2 ·4H 2 O and the poorly characterised Ca(CH 3 COO)(HCOO)·H 2 O. The latter is a frequently observed efflorescence phase found on calcareous objects and it could be also identified as a corrosion phase in a natural history collection of birds' eggs. Elemental and thermal analyses were employed to determine the phase compositions and by Raman and IR spectroscopy the presence of acetate and formate anions in both solids was confirmed. Laboratory X-ray powder diffraction data were used to solve the crystal structures. Ca 3 (CH 3 COO) 4 (HCOO) 2 ·4H 2 O crystallises in a primitive tetragonal unit cell with space group P4 1 2 1 2 and lattice parameters of a = 6.8655(1) Å and c = 45.5454(6) Å, while Ca(CH 3 COO)(HCOO)·H 2 O crystallises in a primitive monoclinic unit cell with space group P2 1 /c and lattice parameters of a = 9.2729(1) Å, b = 6.8002(1) Å, c = 11.2219(2) Å and β = 121.232(1)°. Calcium carboxylate zig-zag chains [Ca(μ 2 -RCOO) + ] n (R = CH 3 or H) are the main motif of both crystal structures. In Ca 3 (CH 3 COO) 4 (HCOO) 2 ·4H 2 O these chains are exclusively composed of acetate anions, whereas in Ca(CH 3 COO)(HCOO)·H 2 O only formate anions are situated in the chains. The remaining places in the 7-8 fold coordination sphere of the calcium cations are filled by water molecules and additional carboxylate anions that interconnect neighbouring chains, which eventually leads to layered motifs in both structures.

Powder samples of Ag3LiIr2O6 and Ag3LiRu2O6 were synthesized from α-Li2IrO3 and Li2RuO3 respectively by ion exchange in an AgNO3 melt. The crystal structures of the title compounds were solved from high resolution laboratory X-ray powder diffraction (XRPD) patterns and from pair distribution function (PDF) analysis using synchrotron X-ray powder diffraction data. In both crystal structures edge sharing LiO6/3- and (Ir/Ru)O6/3-octahedra form honeycomb like layers that are stacked in a staggered fashion. Silver cations, situated in-between the layers mediate the interlayer interactions by linear O-Ag-O bonds. Anisotropic peak broadening in the XRPD patterns and diffuse scattering occurring as streaks in the precession electron diffraction (PED) patterns indicate the presence of stacking faults, which could be also visualized by high resolution transmission electron microscopy (HRTEM). Possible alternative stacking sequences were derived from the ideal crystal and incorporated into a microstructure model. By applying a supercell approach that randomly generates and averages stacking sequences based on transition probabilities and combining it with a grid search algorithm, the microstructures, i.e. the degrees of faulting in the structures of the title compounds were refined to the measured XRPD data. In result the crystal structures of Ag3LiIr2O6 and Ag3LiRu2O6 were found to be vastly faulted with almost no coherence of the stacked layers.

Long-term crystallisation from aqueous copper(ii)-acetate solution after the addition of ammonia at 25 °C led to the formation of a hitherto poorly characterised phase in the verdigris pigment system Cu(CH3COO)2-Cu(OH)2-H2O. Laboratory X-ray powder diffraction (XRPD) was successfully employed to solve the crystal structure. The structure solution reveals a phase composition of the Cu3(CH3COO)4(OH)2·5H2O ≡ 2-1-5 phase, which was also confirmed by thermal analysis. The 2-1-5 phase crystallises in space group P21/c (14) with lattice parameters of a = 12.4835(2) Å, b = 14.4246(2) Å, c = 10.7333(1) Å and β = 102.871(1)°. The crystal structure consists of Cu2(CH3COO)2(CH3COO)1/2(OH)4/3H2O1/6+ dimers that are interconnected by Cu(CH3COO)(CH3COO)1/2(OH)2/31/6- squares forming chains running in the c-direction. Non-coordinating hydrate water molecules are intercalated inbetween the chains and mediate the inter-chain interaction. IR and Raman spectroscopy techniques were also employed to confirm selected aspects of the determined crystal structure. The magnetic properties of the 2-1-5 phase decompose into two independent subsystems: a strongly antiferromagnetically spin exchange coupled magnetic Cu-Cu dimer and a significantly weaker coupled Cu monomer. The light blue colour of the sample originates from a reflectance maximum at 488 nm and significantly differs from the known verdigris phases. An investigation of several historic verdigris pigment samples revealed that this phase occurs both as a minor and a major component. Hence, our reference data for the title compound will help to improve the understanding of the multiphase mixtures occurring in historic verdigris samples.

A powder sample of pure H 3 LiIr 2 O 6 was synthesized from α-Li 2 IrO 3 powder by a soft chemical replacement of Li + with H + . The crystal structure of H 3 LiIr 2 O 6 consists of sheets of edge sharing LiO 6 - and IrO 6 -octahedra forming a honeycomb network with layers stacked in a monoclinic distorted HCrO 2 type pattern. Heavy stacking faulting of the sheets is indicated by anisotropic peak broadening in the X-ray powder diffraction (XRPD) pattern. The ideal, faultless crystal structure was obtained by a Rietveld refinement of the laboratory XRPD pattern while using the LiIr 2 O 6 3- -layers of α-Li 2 IrO 3 as a starting model. The low radial distances of the PDF function, derived from synchrotron XRPD data, as constraints to stabilize the structural refinement. DIFFaX-simulations, structural considerations, high radial distances of the PDF function and a Rietveld compatible global optimization of a supercell were employed to derive a suitable faulting model and to refine the microstructure using the experimental data. We assumed that the overall stacking pattern of the layers in the structure of H 3 LiIr 2 O 6 is governed by interlayer O-HO contacts. From the constitution of the layers, different stacking patterns with similar amounts of strong O-HO contacts are considered. Random transitions among these stacking patterns can occur as faults in the crystal structure of H 3 LiIr 2 O 6 , which quantitatively describe the observed XRPD.

Known synthesis approaches for basic copper(ii) acetates, the main components of historic verdrigis pigments were reinvestigated and revealed to be partially irreproducible. A modification of the reaction conditions led to the successful and reproducible synthesis of the 1-2-0 phase (Cu 3 (CH 3 COO) 2 (OH) 4 = 1Cu(CH 3 COO) 2 ·2Cu(OH) 2 ·0H 2 O). The phase composition was derived from elemental and thermal analysis and confirmed by the crystal structure solution using synchrotron X-ray powder diffraction (XRPD) data. The 1-2-0 phase crystallises in space group Pbca with lattice parameters of a = 20.9742(1) Å, b = 7.2076(1) Å, and c = 13.1220(1) Å. The crystal structure consists of Cu 2 (CH 3 -COO) 2 (OH) 4/3 (OH) 2/2 1/3- dimers, which are interconnected by corner sharing Cu(OH) 2/3 (OH) 2/2 1/3+ squares forming layers perpendicular to the a-axis. The deep blue color of the solid originates from a reflectance maximum at 472 nm and from an absorbance maximum at 676 nm that is comparable with other historic blue pigments like azurite or Egyptian blue. IR- and Raman-spectroscopic properties of the solid were investigated as well, which demonstrated that the obtained product is identical with a previously synthesised verdigris phase that was obtained by applying historical procedures. Therefore, our reference data for the title compound will help to improve the understanding of the multiphase mixtures occurring in historic verdigris samples. The magnetic properties of the 1-2-0 phase were also investigated. At low temperatures the magnetic susceptibility is well described by a spin-1/2 Heisenberg chain with uniform antiferromagnetic nearest-neighbour spin exchange coupling of only one of three Cu magnetic moments. Due to the very strong antiferromagnetic coupling of the Cu 2 (CH 3 -COO) 2 (OH) 4/3 (OH) 2/2 1/3- dimers their contribution to magnetism becomes relevant above ∼140 K, which results in the presence of two distinct temperature regions where Curie-Weiss behaviour of the magnetic susceptibility with different Curie constants and Weiss temperatures is found.

An apatite-type barium phosphate with a high content of cobalt ions in the trigonal channels features slow relaxation of magnetization with an energy barrier U eff of up to 387 cm -1 , which is well above the values for all so far known d-metal based single-molecule magnets (SMMs).

Reaction of cobalt(ii) and nickel(ii) thiocyanate with ethylisonicotinate leads to the formation of [M(NCS) 2 (ethylisonicotinate) 2 ] n with M = Co (2-Co) and M = Ni (2-Ni), which can also be obtained by thermal decomposition of M(NCS) 2 (ethylisonicotinate) 4 (M = Co (1-Co), Ni (1-Ni)). The crystal structure of 2-Ni was determined by single crystal X-ray diffraction. The Ni(ii) cations are octahedrally coordinated by two N and two S bonding thiocyanate anions and two ethylisonicotinate ligands and are linked by pairs of anionic ligands into dimers, that are connected into layers by single thiocyanate bridges. The crystal structure of 2-Co was refined by Rietveld analysis and is isostructural to 2-Ni. For both compounds ferromagnetic ordering is observed at 8.7 K (2-Ni) and at 1.72 K (2-Co), which was also confirmed by specific heat measurements. Similar measurements on [Co(NCS) 2 (4-acetylpyridine) 2 ] n that exhibits the same layer topology also prove magnetic ordering at 1.33 K. Constrained DFT calculations (CDFT) support the ferromagnetic interactions within the layers. The calculated exchange constants in 2-Ni were used to simulate the susceptibility by quantum Monte Carlo method. The single-ion magnetic anisotropy of the metal ions has been investigated by CASSCF/CASPT2 calculations indicating significant differences between 2-Ni and 2-Co.