Strontium in the collinsite structure: Rietveld refinement

The crystal structure of a strontium variety of a rare phosphate—mineral collinsite (Ca_{2 ? x}Sr_x)₂Mg[PO₄] · 2H₂O was solved from powder X-ray diffraction data (λ CuK_α radiation, Ni filter, 12.36° ≤ 2θ ≤ 100.00°, scan step 0.02°, exposure time per step 15 s) by the Rietveld method (R_wp = 4.15%, R_F = 1.03%, R_B = 2.46%); a = 5.8219(1) Å, b = 6.8319(2) Å, c = 5.4713(1) Å, α = 96.965(2)°, β = 108.846(2)°, γ = 107.211(2)°, sp. gr., \(\bar P1\), Z = 1, ρ_calcd = 3.12 g/cm³ (at x = 0.72). The new mineral was discovered in carbonatites from the Kovdor alkaline-ultrabasic massif. The crystallochemical data for collinsite were analyzed and compared with those for isotypic minerals of the fairfieldite group. Characteristic features of the low-temperature geochemistry of strontium were established.     

Synthesis and crystal structure of <Emphasis Type="Italic">N</Emphasis>-(6methoxylbenzothiazol-2-yl)-1-(4-fluorophenyl)<Emphasis Type="Italic">O</Emphasis>,<Emphasis Type="Italic">O</Emphasis>-dipropyl-<Emphasis Type="Italic">α</Emphasis>-aminophosphonate

Molecular and crystal structure of N-(6-methoxybenzothiazol-2-yl)-1-(4-fluorophenyl)-O,O-dipropyl-α-aminophosphonate, C₂₁H₂₆FN₂O₄PS, have been determined by single-crystal X-ray diffraction study. The title compound is tetragonal, with a = 21.35(3) Å, c = 20.16(5) Å, Z = 16, D _x = 1.308 Mg/m³, μ(MoKα) = 0.247 mm^?1, and space group is I4₁/a. The structure was solved by direct method and refined to a final R = 0.0687 for 2370 reflections with I > 2σ(I). The compound shows a fully delocalized benzothiazole system with a sp² hybridization of the N(2). There is a strong intermolecular hydrogen bond between P=O and NH. The crystal structure is stabilized by a strong intermolecular N–H?sO hydrogen bond.     

Prediction of piezoelectric properties of crystal-ceramic composites

In the framework of the model of a piezoelectrically active ferroelectric crystal-ceramic composite of the 0–3 type, the concentration dependences of the effective piezoelectric properties of this composite are determined. Two examples of such composites are discussed: the single-domain PbTiO₃ crystal (Pb_{1 ? x}Ca _itx)TiO₃ ceramic and the polydomain PbTiO₃ crystal (Pb_{1 ? x}Ca_x)TiO₃ ceramic. Based on these examples, we analyzed the effect of the 90° domain structure, the form of crystalline inclusions, the remanent polarization of the ceramics, molar Ca concentration (x), and other factors of the effective piezoelectric coefficients e _3j ^* and d _3j ^* and and their anisotropy. The relation between the piezoelectric polarization of the composite to single-domain inclusions and the anisotropy of its piezoelectric coefficients is also studied.     

Boundary conditions for the formation of a ferromagnetic phase during the deposition of Ti<Subscript>1-<Emphasis Type="Italic">x</Emphasis></Subscript>Co<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>2-δ</Subscript> thin films

The conditions and the mechanism of the formation of a ferromagnetic phase in a Ti_1-xCo _x O_2-δ oxide semiconductor are studied. It is found that the ferromagnetism manifests itself at room temperature in the films of Co-doped TiO_2-δ oxide deposited on SrTiO₃ (100) substrates only within a limited range of charge carrier densities: 2 × 10¹⁸?3 × 10²² cm^?3. The minimum concentration of charge carriers corresponding to the formation of the ferromagnetic phase increases with a decrease in the cobalt content in the material under study. The ferromagnetism in Ti_1-xCo _x O_2-δ thin films can be attributed to Co-enriched clusters with above critical sizes.     

Crystal structure of <Emphasis Type="Italic">p</Emphasis>-carboxyphenylhydrazone benzoylacetone

The crystal structure of p-carboxyphenylhydrazone benzoylacetone is determined. The crystals are monoclinic, a = 13.614(4) Å, b = 11.388(2) Å, c = 20.029(6) Å, β = 104.82(2)°, V = 2339(9) ų, Z = 8, space group C2/c, and R = 0.038 for 1622 reflections with I > 2σ(I). The crystal is built of C₁₇H₁₄N₂O₄ neutral molecules that are linked by O-H?O hydrogen bonds between the carboxyl groups into centrosymmetric pseudodimers. The effect of carboxylation of the phenylhydrazone fragment and the position of the carboxyl group on the molecular packing in the crystal is determined. The N(1)-H(1N)?O(1) intramolecular hydrogen bond (N-H, 0.94 Å; H?O, 1.87 Å; N?O, 2.59 Å; and the N-H?O angle, 133°) is formed in the molecule.     

Na(H<Subscript>2</Subscript>O)[Mn(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>(BP<Subscript>2</Subscript>O<Subscript>8</Subscript>)]: Crystal structure refinement

The crystal structure of synthetic manganese sodium borophosphate hydrate Na(H₂O)[Mn(H₂O)₂(BP₂O₈)] was refined based on X-ray diffraction data. The compound was prepared by soft hydrothermal synthesis in the MnCl₂-Na₃PO₄-B₂O₃-H₂O system. The unit-cell parameters are a= 9.602(1) Å, c= 16.037(3) Å, sp. gr. P6₅22, Z= 6, D _x = 2.57 g/cm³. The water molecules were found to be statistically distributed in the channels of the mixed anionic paraframework consisting of (BO₄) and (PO₄) tetrahedra and [MnO₄(H₂O)₂] octahedra. The hydrogen atoms of the water molecules coordinated to the Mn²⁺ cations were located and their positional and thermal parameters were refined. The crystal-chemical features of borophosphates of the general formula A _x M(H₂O)₂(BP₂O₈)(H₂O) are considered.     

Crystal chemistry of elpidite from Khan Bogdo (Mongolia) and its K- and Rb-exchanged forms

Elpidite Na₂ZrSi₆O₁₅ · 3H₂O [space group Pbcm, a = 7.1312(12), b = 14.6853(12), and c = 14.6349(15) Å] from Khan Bogdo (Mongolia) and its K- and Rb-exchanged forms K_1.78Na_0.16H_0.06ZrSi₆O₁₅ · 0.85H₂O [Cmce, a = 14.054(3), b = 14.308(3), and c = 14.553(3) Å] and Na_1.58Rb_0.2H_0.22ZrSi₆O₁₅ · 2.69H₂O [Pbcm, a = 7.1280(10), b = 14.644(3), and c = 14.642(3) Å] that were obtained by cation exchange at 90°C, as well as K_1.84Na_0.11H_0.05ZrSi₆O₁₅ · 0.91H₂O [Cmce, a = 14.037(3), b = 14.226(3), and c = 14.552(3) Å] and Rb_1.78Na_0.06H_0.16ZrSi₆O₁₅ · 0.90H₂O [Cmce, a = 14.2999(12), b = 14.4408(15), and c = 14.7690(12) Å], obtained at 150°C are studied by single-crystal X-ray diffraction and IR spectroscopy. The base of the structures is a heteropolyhedral Zr-Si-O framework whose cavities accommodate Na (K, Rb) cations and H₂O molecules.     

Crystal structure of zinc(II) hydrated trinuclear complex with monoprotonated ethylenediaminetetraacetate anion(3−), [Zn<Subscript>3</Subscript>(H<Emphasis Type="Italic">Edta</Emphasis>)<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)<Subscript>6</Subscript>]

The crystal structure of the [Zn₃(HEdta)₂(H₂O)₆] complex (I) is determined by X-ray diffraction analysis. The crystals are orthorhombic, a = 14.780 Å, b = 29.699 Å, c = 7.032 Å, Z = 4, and space group Pna2₁. The structural units of crystals I are trinuclear linear molecules, in which the peripheral atoms Zn(1) and Zn(2) each coordinate two N atoms and three O atoms of the HEdta ^3? ligand and the O(w) atom of the H₂O molecule, whereas the central Zn(3) atom coordinates four O(w) atoms of the H₂O molecules and two terminal O atoms of the two HEdta ^3? ligands. The HEdta ^3? ligand fulfills a hexadentate chelating—bridging function. The bond lengths are as follows: Zn-O(HEdta), 2.006(4)–2.123(4) Å; Zn-N, 2.214(6) and 2.128(5) Å; and Zn-O(w), 2.006(6)–2.225(5) Å. In structure I, there is a specific contact formed by hydrogen bonds, owing to which the distance between the central atoms of individual molecules appears to be shorter than that in covalently bonded complexes.     

On the effect of structural and symmetrical features of potassium titanyl phosphate crystals with different contents of niobium,antimony, and zirconium on the second-harmonic intensity

A model is proposed, which shows that, at small deviations from the centrosymmetric state of the atomic structure, the quadratic nonlinear susceptibility of a crystal monotonically decreases with approach of the degree of central symmetry \(\eta _{\overline 1 } \)[φ(r)] of the electric potential function of the crystal structure to unity. The quadratic nonlinear susceptibility of K_{1 ? x} Ti_{1 ? x} Nb _x OPO₄ (x = 0, 0.02, 0.04, 0.11), K_{1 ? x} Ti_{1 ? x} Sb _x OPO₄ (x = 0.01, 0.07, 0.17), and KTi_{1 ? x} Zr _x OPO₄ (x = 0.03, 0.04) crystals has been measured. The degree of central symmetry \(\eta _{\overline 1 } \)[φ(r)] has been calculated for the structures of K_{1 ? x} Ti_{1 ? x} Nb _x OPO₄ (x = 0, 0.04, 0.11), K_{1 ? x} Ti_{1 ? x} Sb _x OPO₄ (x = 0.01, 0.07, 0.17), and KTi_{1 ? x} Zr _x OPO₄ (x = 0.03, 0.04) crystals. It is shown that, at \(\eta _{\overline 1 } \)[φ(r)] > 0.7, the relationship between the quadratic nonlinear susceptibility of the investigated crystals and the degree of their central symmetry \(\eta _{\overline 1 } \)[φ(r)] is in qualitative agreement with the proposed model.     

Crystallization,crystal-structure refinement,and IR spectroscopy of a synthetic hexahydroborite analog

The crystal structure of the hexahydroborite analog Ca[B(OH)₄]₂ · 2H₂O (a = 7.9941(3) Å, b = 6.6321(2) Å, c = 7.9871(3) Å, β = 104.166(4)°, V = 410.58(3) ų, sp. gr. P2/c, Z = 2, ρ_calc = 1.891 g/cm³; Xcalibur S CCD automated diffractometer, 1196 reflections with I > 2σ(I), λMoK _α), which was synthesized by the hydrothermal method via the recrystallization of calciborite CaB₂O₄ (M) in the M ? B₂O₃ ? H₂O system (t = 250°C and P = 70–80 atm), was refined by the least-squares method with anisotropic displacement parameters (H atoms were located; R ₁ = 0.0260). The structure of synthetic hexahydroborite consists of infinite columns running along the c axis. The columns are formed by Ca polyhedra linked together and to [B(OH)₄] orthotetrahedra by sharing edges. Along the two other axes, the translationally equivalent columns are linked only by hydrogen bonds. The presence of a stronger bond between the discrete (Ca-B-O) columns along the shortest (b = 6.6 Å) axis accounts for the possibility of the shift of the columns by 1/2T _b and the formation of the second modification of Ca[B(OH)₄]₂ · 2H₂O. The crystals of synthetic hexahydroborite were studied by IR spectroscopy. A crystal-chemical analysis was performed for a series of natural metaborates with the general formula CaB₂O₄ · nH₂O (CaO: B₂O₃ = 1: 1, n = 0–6), including calciborite CaB₂O₄ and hexahydroborite CaB₂O₄ · 6H₂O as the end members.     

Crystal structure of Rb<Subscript>2</Subscript>Mn<Subscript>3</Subscript>(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>[P<Subscript>2</Subscript>O<Subscript>7</Subscript>]<Subscript>2</Subscript>, a new representative of the family of hydrated diphosphates

The crystal structure of Rb₂Mn₃(H₂O)₂[P₂O₇]₂, a new phase obtained in the form of single crystals under hydrothermal conditions in the MnCl₂–Rb₃PO₄–H₂O system, is determined by X-ray diffraction (Xcalibur-S-CCD diffractometer, R = 0.0270): a = 9.374(2), b = 8.367(2), c = 9.437(2) Å, ß = 99.12(2)°, space group P2₁/c, Z = 2, D_x = 3.27 g/cm³. A correlation between the unit-cell parameters and the size of cations forming the crystal structures of isostructural A₂M₃(H₂O)₂[P₂O₇]₂ diphosphates (A = K, NH₄, Rb, or Na; _M = Mn, Fe, Co, or Ni) is revealed. It is shown that, due to the topological similarity, the structures of diphosphates and orthophosphates of the farringtonite structural type can undergo mutual transformations.     

Synthesis and characterization of 9-(4-nitrophenyl)3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahydro-1,8(2H,5H) acridinedione and its methoxyphenyl derivative

9-(4-Nitrophenyl)-3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahydro-1,8(2H,5H) acridinedione (NTHA) crystallizes in orthorhombic space group P2₁2₁2₁ with a = 5.9716(1) Å, b = 18.0476(3) Å, c = 19.2445(2) Å, V = 2074.04(5) ų, Z = 4, D_cal = 1.263 Mg m^?3 and R = 0.0521 (wR = 0.1326) for 4078 observed reflections. 9-(4-Nitrophenyl)-10-(4-methoxyphenyl)-3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahydro-1,8(2H,5H) acridinedione NMTHA, crystallizes in monoclinic space group P2₁/c with a = 15.669(5) Å, b = 10.652(4) Å, c = 18.337(6) Å, β = 108.25(1)^°, V = 2906.66(2) ų, Z = 4, D_cal = 1.245 Mg m^?3 and R = 0.0725 (wR = 0.1847) for 5105 observed reflections. The experimental values are compared with the theoretical values calculated based on the semiemperical methods. The structures are stabilized by N–H?sO and C–H?sO types of intermolecular interactions in addition to van der Waals forces.     

Molecular Dynamics Simulation of the Structure and Ion Transport in the Ce<Subscript>1 – <Emphasis Type="Italic">x</Emphasis></Subscript>Gd<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>2 – δ</Subscript>|YSZ Heterosystem

Molecular dynamics simulation has been used to develop a realistic atomistic model of two-layer Ce_{1 – x}Gd _x O_{2 – δ}|YSZ heterosystem. It is shown that Ce_{1 – x}Gd _x O_{2 – δ} and YSZ layers (about 15 and 16 Å thick, respectively) retain their crystal structure on the whole. The main structural distortions are found to occur near the Ce_{1 – x}Gd _x O_{2 – δ}|YSZ geometric interface, within a narrow interfacial region of few angstroms thick. Both the generalized diffusion characteristics of the system as a whole and the oxygen diffusion coefficients in the layers are calculated, and the diffusion activation energies are determined.     

X-ray diffraction study of Rb<Subscript>2</Subscript>[(UO<Subscript>2</Subscript>)<Subscript>2</Subscript>(CrO<Subscript>4</Subscript>)<Subscript>3</Subscript>(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>] · 4H<Subscript>2</Subscript>O

The compound Rb₂[(UO₂)₂(CrO₄)₃(H₂O)₂] · 4H₂O was studied by X-ray diffraction. The crystals are monoclinic, a = 10.695(2) Å, b = 14.684(3) Å, c = 14.125(3) Å, β = 108.396(4)°, sp. gr. P2₁/c, Z = 4, V = 2104.9(7) ų, and R = 0.0491. The main structural units are layers consisting of [(UO₂)₂(CrO₄)₃(H₂O)₂]^2? anions belonging to the crystal-chemical group A ₂ T ₂ ³ B ²M ₂ ¹ (A = UL ₂ ²⁺ , T ³ and B ² are CrO ₄ ^2? , and M ¹ is H₂O) of uranyl complexes. The uranium-containing layered groups are held together by electrostatic interactions with rubidium cations, as well as by hydrogen bonds with the participation of inner- and outer-sphere water molecules.     

The crystal structure of calcium aqua{ethylenediaminetetraacetato(3-)}nickelate(II) tetrahydrate,Ca[Ni(H<Emphasis Type="Italic">Edta</Emphasis>)(H<Subscript>2</Subscript>O)]<Subscript>2</Subscript>·4H<Subscript>2</Subscript>O

The crystal structure of Ca[Ni(HEdta)(H₂O)]₂ · 4H₂O (HEdta ^3?is a protonated anion of ethylenediaminetetraacetic acid) is determined. The unit-cell parameters are as follows: a = 7.706(1), b = 14.923(9), and c = 26.570(5) Å; V = 3055.6(2.4) ų; Z = 8; and space group Pbcn. Crystals are shaped as tetragonal prisms and colored green, which is not characteristic of this class of compounds. The structure is built of Ca²⁺ cations, octahedral [Ni(HEdta)(H₂O)]^? complex anions, and crystallization water molecules. In the complex anion, one of the acetate branches is free of coordination, whereas the remaining three branches coordinate the central atom forming glycinate metallocycles. The structure is based on sandwich layers, which are formed by networks of flat tetragonal Ca[Ni(HEdta)(H₂O)]₄(H₂O)₂ fragments adjoining one another by vertices.     

Crystal and molecular structure of 2-[(4-nitrophenyl)carbonyl]cyclohex-1-ene-1-yl 4-nitrobenzoate

The crystal structure of 2-[(4-nitrophenyl)carbonyl]cyclohex-1-ene-1-yl 4-nitrobenzoate is studied (T = 173 K, R1 = 0.0354 for 2713 observed reflections). This crystal is orthorhombic, a = 7.8367(8) Å, b = 9.6082(10) Å, c = 23.856(3) Å, V = 1796.3(3) ų, space group P2₁2₁2₁, and Z = 4. The molecule has a folded configuration, which is stabilized by π-π interactions between its two parts. A system of intermolecular C-H...O hydrogen bonds (H...O, 2.44–2.67 Å; CHO angles 122°–169°) and intramolecular C-H...O contacts closing five-membered cycles (H...O, 2.42–2.59 Å; CHO angles 96°–102°) are formed in the structure.     

Crystal structure of SrFe(<Emphasis Type="Italic">EDTA</Emphasis>)Cl · 5H<Subscript>2</Subscript>O

The crystal structure of the SrFe(Edta)Cl · 5H₂O (I) complex is determined. The crystals are monoclinic, a = 7.530(4) Å, b = 10.575(3) Å, c = 23.308(10) Å, β = 95.75(4)°, Z = 4, and space group P2₁/c. The structural units of I are infinite ribbons of the molecular type that are formed by tetranuclear fragments. A tetranuclear fragment involves the centrosymmetric positively charged dimer group [Sr(H₂O)₄Cl] ₂ ²⁺ at the center and the [Fe(Edta)(H₂O)]_? anionic complexes, which compensate for the positive charge of the dimer group, at the periphery. These constituents are bound via bridging oxygen atoms of the Edta ligands. The coordination number of the Sr atom is nine. The Sr-O bond lengths lie in the range between 2.552 and 2.766 Å, the Sr-Cl bond length is 3.216(3) Å, and the Sr?Sr distance is 4.371(1) Å. The parameters of the [Fe(Edta)(H₂O)]^? group are within the range of values observed in such complexes: Fe-O, 1.996–2.086(3) Å; Fe-O(w), 2.110(4) Å; and Fe-N, 2.289(4) and 2.327(4) Å. Separate ribbons are linked by hydrogen bonds involving all H₂O molecules and terminal oxygen atoms of the Edta ligand.     

Synthesis and structure of Cs[UO<Subscript>2</Subscript>(SeO<Subscript>4</Subscript>)(OH)] · <Emphasis Type="Italic">n</Emphasis>H<Subscript>2</Subscript>O (<Emphasis Type="Italic">n</Emphasis> = 1.5 or 1)

The synthesis and single-crystal X-ray diffraction study of Cs[UO₂(SeO₄)(OH)] · 1.5H₂O (I) and Cs[UO₂(SeO₄)(OH)] · H₂O (II) are performed. Compound I crystallizes in the monoclinic crystal system, a = 7.2142(2) Å, b = 14.4942(4) Å, c = 8.9270(3) Å, β = 112.706(1)°, space group P2₁/m, Z = 4, and R = 0.0222. Compound II is monoclinic, a = 8.4549(2) Å, b = 11.5358(3) Å, c = 9.5565(2) Å, β = 113.273(1)°, space group P2₁/c, Z = 4, and R = 0.0219. The main structural units of crystals I and II are [UO₂(SeO₄)(OH)]^? layers which belong to the AT ³ M ² crystal chemical group of uranyl complexes (A = UO ₂ ²⁺ , T ³ = SeO₄ ^2?, and M ² = OH^?). In structure I, johannite-like layers are found. Structure II is a topological isomer of I. The two structures differ in the number of U(VI) atoms bound to the central atom by all bridging ligands.     

Crystal structure of CoUO<Subscript>2</Subscript>(SO<Subscript>4</Subscript>)<Subscript>2</Subscript> · 5H<Subscript>2</Subscript>O at 293 K

Single crystals of cobalt uranyl sulfate are grown. The crystal structure is established by X-ray diffraction: the orthorhombic system, sp. gr. Pmc2₁, a = 6.452(2) Å, b = 8.295(2) Å, c = 11.288(3) Å, R₁ = 0.0303, wR₂ = 0.0735 for reflections with I > 2σ(I). The structure of CoUO₂(SO₄)₂ · 5H₂O consists of infinite two-dimensional uncharged [CoUO₂(SO₄)₂H₂O]_2∞ layers, which are linked to each other by hydrogen bonds.     

Crystal and molecular structure of barium cyclohexane-1,2-diamine-<Emphasis Type="Italic">N,N,N′,N′</Emphasis>-tetraacetatonickeloate decahydrate Ba[Ni(<Emphasis Type="Italic">Cdta</Emphasis>)] · 10H<Subscript>2</Subscript>O

The X-ray diffraction study of Ba[Ni(Cdta)] · 10H₂O is performed (R1 = 0.0441 for 5136 observed reflections). The crystals are triclinic, a = 8.833(2) Å, b = 9.025(2) Å, c = 16.922(3) Å, α = 80.56(3)°, β = 82.77(3)°, γ = 76.98(3)°, Z = 2, and space group \(P\bar 1\). The crystal is built of the [Ni(Cdta)]^2? anionic complexes, the [Ba(H₂O)₆]²⁺ hydrated cations, and crystallization water molecules. The distorted octahedral coordination of the Ni atom includes two N and four O atoms of the Cdta^4? ligand (mean Ni-N, Ni-O_G, and Ni-O_R re 2.080, 2.082, and 2.036 Å, respectively). The irregular nine-fold coordination of the Ba atom consists of six O atoms of water molecules and three O(Cdta) atoms from three anionic complexes (Ba—O, 2.715–3.090 Å). With consideration for the bonds with three Ba atoms, the Cdta^4? ligand is octadentate (2N + 6O) and fulfills the pentadentate μ₄-bridging function. The structural units are linked through an extended network of hydrogen bonds.