Illite is a common clay mineral that is found in a wide range of geological settings. The good thermal stability and non-swelling properties of illite make it valuable in ceramic materials, paints and coatings, drilling fluids, agriculture and geological studies. To gain a deeper understanding of the physical and chemical properties of illite, in the present paper the atomic and electronic structures of a typical trans-vacant 1M Al-rich illite were constructed and calculated using density functional theory. The calculated indirect band gap of Al-rich illite was 4.99 eV. The electronic analysis revealed that the interactions in the tetrahedral sheet were more stable than those in the octahedral sheet. The substitution of Al atoms noticeably reduced the stability of the tetrahedral sheet in Al-rich illite. Other properties of Al-rich illite, including the density of states, electron population/charge, electronic charge density and bonding interaction, are also discussed and analysed in detail.

Synthetic samples of krautite, Mn[AsO3(OH)]⋅H2O, koritnigite, Zn[AsO3(OH)]⋅H2O and cobaltkoritnigite, Co[AsO3(OH)]⋅H2O, were used for calorimetric experiments. For krautite and koritnigite, single-crystal X-ray diffraction was used to determine positions of all atoms, including the H atoms. These data allowed the hydrogen-bond network and the function of H2O molecules in these structures to be determined. The structural formulae are Mn4(H2[3]O)4[AsO3(OH)]4 and Zn4(H2[3]O)2[AsO3(OH)]4(H2[4]O)2, where [3]H2O and [4]H2O are the ‘transformer’ and ‘non-transformer’ H2O groups, respectively. Even though the principal features of these structures are identical, the details, especially those regarding the H2O groups, differ from one structure to another structure in this group. The solubility products (log Ksp) were determined from calorimetric data, that is, from the experimentally measured enthalpies of formation and entropies. They relate to the reaction M[AsO3(OH)]⋅H2O → M2+ + HAsO42– + H2O and are –6.10 for krautite, –6.88 for koritnigite and –6.83 for cobaltkoritnigite. We also estimated the log Ksp for magnesiokoritnigite as –2.0. Calculation of phase diagrams shows that all these phases originate under acidic conditions from solutions with high metal and arsenate concentration. They are restricted to local environments, to pockets that maintain such high concentrations over the time necessary for crystallisation of the krautite-group phases.

The structure, powder diffraction patterns and bandgap measurements of a series of manganese- and tungsten-containing alkaline-earth double perovskites (CaxSr2−x)MnWO6 (x = 0.25, 0.5, 0.75, 1.5, 1.75) have been investigated. Powder X-ray diffraction patterns of this series of compounds measured at room temperature have been submitted to be included in the Powder Diffraction File (PDF). These compounds crystallize in monoclinic space group P21/n (No.14). From (Ca1.75 Sr0.25)MnWO6 to (Ca0.25Sr1.75)MnWO6, lattice parameters a range from 5.6729(2) Å to 5.6774(4) Å, b from 5.5160(2) Å to 5.6638(4) Å, c from 7.8741(3) Å to 8.0051(4) Å, V from 240.39(2) Å3 to 257.410(12) Å3, and Z = 2. These compounds are pseudo-tetragonal. They all consist of distorted MnO6 and WO6 octahedra with rotational mismatch angles and tilt angles with respect to each other. For (CaxSr2−x)MnWO6, as x increases, the mismatch angles for MnO6 octahedra increase from 7.96 (6)° to 13.12(8)° and from 9.28(7)° to 14.87(9)° for WO6 octahedra. Correspondingly, the tilt angles range from 11.60(15)° to 14.20(3)° for MnO6, and from 13.34(2)° to 16.35(3)° for WO6. Bandgap measurements suggest that these compounds to be direct-allowed semiconductors with bandgaps ranging from 1.5 to 2.5 eV, indicating that members of (CaxSr2−x)MnWO6 are potential photocatalysts and photovoltaic materials that absorb visible light of the solar spectrum.

We report the crystal structures of eight new synthetic multinary Rb–Cu sulfates representing four new structure types: δ-Rb2Cu(SO4)2, γ-RbNaCu(SO4)2, γ-RbKCu(SO4)2, Rb2Cu2(SO4)3, Rb2Cu2(SO4)3(H2O), β-Rb2Cu(SO4)Cl2, β-Rb4Cu4O2(SO4)4⋅(Cu0.83Rb0.17Cl) and Rb2Cu5O(SO4)5. The determination of their crystal structures significantly expands the family of anhydrous copper sulfates. Some of the anhydrous rubidium copper sulfates obtained turned out to be isostructural to known compounds and minerals. Rb2Cu5O(SO4)5 is isostructural to cesiodymite, CsKCu5O(SO4)5 and cryptochalcite, K2Cu5O(SO4)5. Rb2Cu2(SO4)3 also shows an example of crystallisation in the already known structure type first observed for synthetic K2Cu2(SO4)3. ‘Hydrolangbeinite’, Rb2Cu2(SO4)3(H2O), was formed as a result of a minor hydration of the initial mixture of reagents.

The minerals and synthetic framework compounds of the A2Cu(SO4)2 series demonstrate a vivid example of morphotropism with the formation of structural types depending on the size of the cations residing in the cavities of the [Cu(SO4)2]2– open framework. To date, five types (α, β, γ, δ and ε) can be distinguished. We propose to call this series of compounds ‘saranchinaite-type’, as the stoichiometry A2Cu(SO4)2 was first encountered during the discovery and description of saranchinaite, Na2Cu(SO4)2.

The discovery of β-Rb2Cu(SO4)Cl2, a new monoclinic polymorph of chlorothionite, seems to be of particular interest considering the recently discovered interesting magnetic properties of synthetic K2Cu(SO4)X2 (X = Cl and Br) and Na2Cu(SO4)Cl2.

In these new structural architectures, a number of features have been revealed that were seldom observed previously. The first is the bidentate coordination of the sulfate tetrahedron via edge-sharing with the Cu2+-centred coordination polyhedron. Until recently, such coordination was known only for the chlorothionite structure. The second is formation of ‘high-coordinate’ CuO7 polyhedra. The structures of the new compounds suggest that such coordination is not in fact so uncommon, at least among anhydrous alkali copper sulfates. All of the described features clearly indicate the importance of further systematic studies of anhydrous copper-sulfate systems. Their exploration, particularly of the new copper-oxide substructures with new coordination environments, is highly likely to lead to new potentially interesting magnetic properties due to the unusual arrangements of magnetically active Cu2+ cations.

In addition to experimental details on the synthesis of rubidium analogues of anhydrous potassium and sodium sulfates, this work also provides an analysis and a brief review of the geochemistry of rubidium in volcanic environments.

The effect of zirconium alloying on the crystal structures and mechanical properties of binary tungsten–zirconium alloys is investigated in this study using the first-principles method. Firstly, we investigate the cell volumes, lattice constants, and formation energies of binary W1−xZrx (x = 0, 0.0625, 0.125, 0.1875, 0.25, and 0.5) alloys. It is shown that binary tungsten–zirconium alloys maintain BCC structures. When the concentration of zirconium atoms is lower than 12.5%, the structures of binary tungsten–zirconium alloys can be thermodynamically stable. The elastic constants of binary tungsten–zirconium alloys are calculated based on the optimized atomic lattice. Then, the elastic modulus and other mechanical parameters are deduced according to the relevant formulas. It is shown that the mechanical strength of binary tungsten–zirconium alloy decreases with an increasing concentration of zirconium atoms, which is lower than the mechanical strength of pure tungsten metal. However, the mechanical strength of binary tungsten–zirconium alloys is higher than that of pure zirconium metal. In addition, zirconium alloying can be effective in improving the ductility of pure tungsten metal.

(1 − x)Ba(Mg1/3Ta2/3)O3–xBa(Co1/3Nb2/3)O3 (BMT–BCN, x = 0.0, 0.20, 0.25, 0.30, 0.40) ceramics were prepared using the traditional solid-state reaction method. X-ray diffraction patterns have shown that the intensities of (001) and (100) super-lattices decrease with the increase in the BCN content. Seven main Raman vibrational modes are observed, assigned, and illustrated, in particular. Raman shifts of Eg(O) modes and the FWHM values of F2g(O)/A1g(O) modes have close relationship with the dielectric properties. The calculated values by the four-parameter semiquantum model based on IR reflectivity match well with the measured data (@3.8 GHz), which means that most of dielectric contribution to the system may be ascribed to the absorption of structural phononic oscillations at the infrared region, and the contribution from the scattering of the defective phonons is small. The contributions of each vibrational mode on the dielectric responses were investigated in detail, indicating that the low-frequency modes (A2u(1) and Eu(1)) have a decisive role to the dielectric properties.

Copiapite is a mineral of iron- and sulphate-rich acidic environments and has a general formula AFe3+4 (SO4)6(OH)2(H2O)20, where A = Fe2+, 2/3Fe3+, 2/3Al3+, Mg, Zn. The structure is built by infinite tetrahedral-octahedral chains and isolated octahedrally coordinated A sites. Our synthetic and natural copiapite samples can be divided into two large groups based on the orientation of the structural fragments. One group comprises copiapite phases where A = Al3+, Fe2+ or Fe3+ and we designate it as the structural type AL. The other group consists of copiapite with A = Mg2+, Zn2+ or Ni2+ and this is the structural type MG. The solid-solution series between Fe3+ and Al3+ copiapite is continuous. The series between Mg2+-Al3+, Mg2+-Fe3+ and Mg2+-Al3+-Fe3+ copiapite are not continuous; the samples with intermediate compositions contain two copiapite phases, one of the type AL and one of the type MG. The series between Mg2+ and Zn2+ copiapite is continuous only at 25°C. At 75°C, the Zn-rich portion of this systemcrystallizes a copiapite-like phase whose structure may be a superstructure of copiapite. The series between Al-Fe2+ and Mg-Fe2+ copiapite are not continuous and show complex behaviour of the intermediate compositions.

Two new members of the atacamite family were discovered recently in the Sadamisaki Peninsula, Ehime Prefecture, Japan. Iyoite, MnCuCl(OH)3, is an Mn-Cu ordered analogue of botallackite, while misakiite, Cu3Mn(OH)6Cl2, is an Mn-rich analogueof kapellasite. Both minerals occur in manganese ore crevices in close association with one another. Iyoite forms radial and dendritic aggregates consisting of pale green, bladed crystals. Misakiite commonly exists in emerald green, tabular, hexagonal crystals. The densities of iyoite andmisakiite were calculated to be 3.22 and 3.42 g cm–3 based on their empirical formulae and powder X-ray diffraction data. Under the same axial setting of botallackite, iyoite is monoclinic, space group P21/m, a = 5.717(2), b = 6.586(2), c= 5.623(3) Å, β = 88.45(3)° and V = 211.63(15) Å3. Misakiite is trigonal, space group P3m1, with a = 6.4156(4), c = 5.7026(5) Å and V = 203.27(3) Å3. The structures of both mineralsare classified as layer type and the two are closely related. These new minerals were formed by the reaction between seawater and naturally-occurring manganese ores including native copper. These minerals are challenging to produce synthetically. Misakiite was synthesized successfully usinga hydrothermal method, while iyoite could not be made.

Nucleotide excision repair (NER) is a highly versatile and efficient DNA repair process, which is responsible for the removal of a large number of structurally diverse DNA lesions. Its extreme broad substrate specificity ranges from DNA damages formed upon exposure to ultraviolet radiation to numerous bulky DNA adducts induced by mutagenic environmental chemicals and cytotoxic drugs used in chemotherapy. Defective NER leads to serious diseases, such as xeroderma pigmentosum (XP). Eight XP complementation groups are known of which seven (XPA–XPG) are caused by mutations in genes involved in the NER process. The eighth gene, XPV, codes for the DNA polymerase ɳ, which replicates through DNA lesions in a process called translesion synthesis (TLS). Over the past decade, detailed structural information of these DNA repair proteins involved in eukaryotic NER and TLS have emerged. These structures allow us now to understand the molecular mechanism of the NER and TLS processes in quite some detail and we have begun to understand the broad substrate specificity of NER. In this review, we aim to highlight recent advances in the process of damage recognition and repair as well as damage tolerance by the XP proteins.

Ongoing software developments for creating three-dimensional (3D) printed crystallographic models seamlessly from Crystallographic Information Framework (CIF) data (*.cif files) are reported. Color versus monochrome printing is briefly discussed. Recommendations are made on the basis of our preliminary printing efforts. A brief outlook on new materials for 3D printing is given.

The X-ray diffraction powder patterns were prepared and the crystal structures were refined for the double-perovskite series of compounds, Sr2RSbO6 (R = Pr, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, Tm, Yb, and Lu). We found the structures of the entire Sr2RSbO6 series to be monoclinic with space group P21/n (no. 14), and Z = 2. From R = Lu to Pr, the lattice parameters “a” range from 5.7779(2) to 5.879 05(8) Å, “b” range from 5.7888(2) to 5.969 52(9) Å, “c” range from 8.1767(3) to 8.369 20(12) Å, “β” range from 90.112(2)° to 90.313(1)°, and “V” range from 273.483(4) to 293.714(7) Å3. These lattice parameters follow the well-established trend of “lanthanide contraction”. The R 3+ and Sb5+ ions are found to be fully ordered in the double-perovskite arrangement of alternating corner-sharing octahedra in a zigzag fashion. The SrO12, RO6, and SbO6 cages are all found to have distorted coordination environments. Powder diffraction patterns of these compounds have been prepared, submitted, and published in the Powder Diffraction File.

The crystal structure of SiAl5O2N5 was characterized by laboratory X-ray powder diffraction (CuKα1). The title compound is hexagonal with space group P63/mmc (Z = 2). The unit-cell dimensions are a = 0.303153(3) nm, c = 3.28153(3) nm, and V = 0.261178(5)  nm3. The initial structural model was successfully derived by the direct methods and further refined by the Rietveld method. The final structural model showed the positional disordering of two of the four (Si,Al) sites. The maximum-entropy method-based pattern fitting (MPF) method was used to confirm the validity of the split-atom model, in which conventional structure bias caused by assuming intensity partitioning was minimized. The reliability indices calculated from the MPF were R wp = 5.00%, S (=R wp/R e) = 1.25, R p = 3.76%, R B = 1.26%, and R F  = 0.90%. The disordered crystal structure was successfully described by overlapping four types of domains with ordered atom arrangements. The distribution of atomic positions in each of the domains can be achieved in the space group P63 mc. Two of the four types of domains are related by a pseudo-symmetry inversion, and the two remaining domains also have each other the inversion pseudo-symmetry.

The crystal structure of the S642A mutant of mitochondrial aconitase (mAc) with citrate bound has been determined at 1.8 Å resolution and 100 K to capture this binding mode of substrates to the native enzyme. The 2.0 Å resolution, 100 K crystal structure of the S642A mutant with isocitrate binding provides a control, showing that the Ser → Ala replacement does not alter the binding of substrates in the active site. The aconitase mechanism requires that the intermediate product, cis-aconitate, flip over by 180° about the Cα–Cβ double bond. Only one of these two alternative modes of binding, that of the isocitrate mode, has been previously visualized. Now, however, the structure revealing the citrate mode of binding provides direct support for the proposed enzyme mechanism.