Space Group Ccca Research Articles

Structural, morphological, and photoluminescence properties of RE (RE = Dy3+ , Eu3+ , Sm3+ )-doped CaAlBO4 phosphor synthesized by combustion method.

The CaAlBO4 :RE (RE = Dy3+ , Eu3+ , Sm3+ ) phosphor were prepared via combustion synthesis and studied by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) analysis, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), photoluminescence (PL) spectra and CIE coordinates. The phase formation of the obtained phosphor was analyzed by XRD and the result was confirmed by standard PDF Card No. 1539083. XRD data successfully indicated pure phase of CaAlBO4 phosphor. The crystal structure of CaAlBO4 phosphor is orthorhombic with space group Ccc2 (37). The SEM image of CaAlBO4 phosphor reveals an agglomerated morphology and non-uniform particle size. The EDS image provides evidence of the elements present and the chemical makeup of the materials. Under the 350 nm excitation, the emission spectrum of Dy3+ activated CaAlBO4 phosphor consists of two main groups of characteristic peaks located at 484 and 577 nm which are ascribed to 4 F9/2 → 6 H15/2 and 4 F9/2 → 6 H13/2 transition of Dy3+ respectively. The PL emission spectra of CaAlBO4 :Eu3+ phosphor shows characteristics bands observed around 591 and 613 nm, which corresponds to 5 D0 → 7 F1 and 5 D0 → 7 F2 transition of Eu3+ respectively, upon 395 nm excitation wavelength. The emission spectra of Sm3+ activated CaAlBO4 phosphor shows three characteristic bands observed at 565, 601 and 648 nm which emits yellow, orange and red color. The prominent emission peak at the wavelength 601 nm, which is attributed to 4 G5/2 → 6 H7/2 transition, displays an orange emission. The CIE color coordinates of CaAlBO4 :RE (RE = Dy3+ , Eu3+ , Sm3+ ) phosphor are calculated to be (0.631, 0.368), (0.674, 0.325) and (0.073, 0.185). As per the obtained results, CaAlBO4 :RE (RE = Dy3+ , Eu3+ , Sm3+ ) phosphor may be applicable in eco-friendly lightning technology.

Crystal structure, hirshfeld surface analysis and phase transformation behaviour of diisopropylammonium chloride hemihydrate crystals

The phase stability of the rarely studied diisopropylammonium chloride hemihydrate (DPC-HH) was investigated in a range of temperature from 100 K to 503 K. The single crystals of DPC-HH grown from methanol solution belong to orthorhombic crystal system with space group Ccca at ambient conditions (296 K) and do not show any phase transformation till 100 K upon cooling whereas it is physically less stable when stored at room temperature due to host-guest nature of the diisopropylammonium chloride (DPC) and water in the DPC-HH lattices. While heating above room temperature dehydration of the hydrate molecules occurs which leads to the crystallization of anhydrous DPC in monoclinic crystal system with space group P21 at 342 K and further at 439.7 K the DPC undergoes a ferroelectric to paraelectric phase transition through a structural transformation from monoclinic P21 to P21/m which is reversible. The Hirshfeld surface and fingerprint plots were used to study the intermolecular interactions of DPC-HH. The intermolecular H⋯H contacts was most significant interactions present in the crystal with over 72% of the total Hirshfeld surface. Powder X-ray diffraction, Raman and FT-IR spectroscopy, TGA and DSC techniques were employed to monitor and confirm the phase stability of DPC-HH crystals and ferro-para transformations occur in the DPC crystal system.

A New Lithium‐Rich Zeolitic 10‐MR Zincolithosilicate MZS‐1 Hydrothermally Synthesized under High Pressure and Characterized by 3D Electron Diffraction

AbstractWe report the structure of a new high lithium content zincolithosilicate (MZS‐1) obtained after hydrothermal treatment under high pressure from a glass precursor. After synthesis microcrystalline mixture of phases was obtained among which the main phase was unknown. Due to the sub micrometric size of the crystallites its structure was determined from precession‐assisted 3D electron diffraction measured at 100 K and refined using the dynamical theory of diffraction. More accurate lattice parameters are obtained from Rietveld refinement of synchrotron powder data collected at the ambient temperature. The characteristic framework is described at the ambient temperature using an average unit cell a0=8.57999(5) Å, b0=14.12332(8) Å, c0=4.96827(3) Å in the space group Ccc2. The structure of the new zeolitic 10‐membered ring zincosilicate with chemical formula per unit cell (SiO2)2Zn0.408LiO(OH)2(Li,H)2.184 (Z=4) is composed of undulated silicate layers made of fused 6‐membered rings connected via vertices of (Zn,Li)O4 tetrahedra. A weak superstructure doubling the a0 parameter is observed and is explained by a Zn/Li ordering within the (Zn,Li)O4 layers.

Hydrothermal synthesis and investigation of optical properties of Nb5+-doped lithium silicate nanostructures

The hydrothermal synthesis and optical properties of Nb5+-doped lithium metasilicate and lithium disilicate nanomaterials were investigated. The microstructures and morphologies of the synthesized Li2 -2x Nb2x SiO3 + δ and Li2 -2x Nb2x Si2O5 + δ nanomaterials were studied by powder X-ray diffraction and scanning electron microscopy techniques, respectively. The synthesized niobium-doped lithium metasilicate and lithium disilicate nanomaterials, respectively, are isostructural with the standard bulk Li2SiO3 (space group Cmc21) and Li2Si2O5 (space group Ccc2) materials. The photoluminescence spectra of the synthesized materials are studied. The measured optical properties show dependence of the dopant amounts in the structure.

Hydrothermal synthesis and investigation of optical properties of Nb5+-doped lithium silicate nanostructures

The hydrothermal synthesis and optical properties of Nb5+-doped lithium metasilicate and lithium disilicate nanomaterials were investigated. The microstructures and morphologies of the synthesized Li2−2x Nb2x SiO3+ δ and Li2−2x Nb2x Si2O5+ δ nanomaterials were studied with powder X-ray diffraction and scanning electron microscopy techniques, respectively. The synthesized niobium-doped lithium metasilicate and lithium disilicate nanomaterials, respectively, are isostructural with the standard bulk Li2SiO3 (space group Cmc21) and Li2Si2O5 (space group Ccc2) materials. Photoluminescence spectra of the synthesized materials are studied. The measured optical properties show dependence on the dopant amounts in the structure.

Quantum Oscillations in Ultra Pure PtSn<sub>4</sub>

PtSn4 is a non-congruently melting compound in the Pt-Sn binary phase diagram, crystallizing in the centrosymmetric space group Ccca. We report on single crystal growth, temperature dependent electrical resistivity, isothermal field-dependent magnetization and magnetostriction, and on band structure calculations of this transition metal compound. The high quality of the sample makes it possible to observe clearly resolved quantum oscillations in the magnetization data for temperatures as high as 20 K and in magnetic fields as low as 10 kOe. We found several frequencies along the three crystallographic directions and could relate them to several extremal orbits on the Fermi surface.

Hydrothermal synthesis, characterization, and investigation of optical properties of Sb3+-doped lithium silicates nanoparticles

Abstract The hydrothermal synthesis and optical properties of undoped and Sb3+-doped lithium metasilicate and lithium disilicate nanomaterials were investigated. The microstructures and morphologies of the synthesized Li2−2x Sb2x SiO3 and Li2−2x Sb2x Si2O5 nanoparticles were studied with powder X-ray diffraction and scanning electron microscopy techniques, respectively. The synthesized undoped and doped lithium metasilicate and lithium disilicate nanomaterials, respectively, are isostructural with the standard bulk Li2SiO3 (space group Cmc21) and Li2Si2O5 (space group Ccc2) materials. The electronic absorption and photoluminescence spectra of the synthesized materials are studied. The measured optical properties show dependence on the dopant amounts in the structure.

Synthesis, Crystal Structure, and Properties of a Cadmium(II) Complex with the Flexible Ligand (1′H‐[2, 2′]Biimidazoly‐1‐yl)‐acetic Acid

AbstractA novel coordination polymer {[Cd(BDAC)]2·H2O}n (1) [HBDAC = (1′H‐[2, 2′]biimidazoly‐1‐yl)‐acetic acid] was synthesized under hydrothermal conditions and characterized by elemental analysis and single‐crystal X‐ray diffraction. Complex 1 crystallizes in the acentric orthorhombic space group Ccc2. The Cd1 atoms and BDAC2– ligands construct [Cd1(BDAC)] rhomboid grid (4, 4)‐topology layer motifs, whereas the Cd2 atoms and BDAC2– ligands form [Cd2(BDAC)] 1D coordination polymer ribbons. Furthermore, adjacent lay motifs are linked into 3D net structures by 1D coordination polymer ribbons with 4‐connected 3D trinodal {4282102}{4462}{43628}2 topology. The measurement of electric hysteresis loops indicated that complex 1 displays a ferroelectric characteristic.

Cluster self-organization of silicate and germanate systems: Suprapolyhedral precursor nanoclusters and self-assembly of tetrahedral structures of the family A2T2O5 (A = Li, Na; T = Si, Ge): Li2T2O5, Li4Ge3SiO10, Li2Si2O5, and A2Si2O5

Modeling of atomic species (An clusters in the form of atoms or Kn polyhedra, where n is the number of atoms or polyhedra) corresponding to the initial stage of evolution of a chemical system has been carried out. Three series of K4 clusters built of different T tetrahedra (L and T) have been recognized. For L2T2 clusters, six geometrically and symmetrically different types of suprapolyhedral clusters have been discovered. The model has been used to identify precursor clusters in A2T2O5 (A = Li, Na; T = Si, Ge) framework structures: A-type Li2T2O5 with space group Cc, B-type Li4Ge3SiO10 with space group Abm2, C-type Li2Si2O5 with space group Ccc2, and D-type A2Si2O5 with space group Pbcn. Three (of the six possible) types of suprapolyhedral precursor nanoclusters K4 in the four structures have been identified. The full 3D reconstruction of the self-assembly scenario of crystal structures is as follows: precursor nanocluster → primary chain → microlayer → microframework → … framework. The bifurcation of structural evolution pathways (structural branching points) at the suprapolyhedral level for type A and B structures is found to occur only when a microframework is formed of equivalent microlayers.

Mechanochemical synthesis in copper(ii) halide/pyridine systems: single crystal X-ray diffraction and IR spectroscopic studies

Whereas complexes of divalent metal halides (X = Cl, Br, I) with/from pyridine commonly crystallise as trans-[M(py)(4)X(2)]·2py, M on a site of 222 symmetry in space group Ccca, true for CuCl(2) and CuBr(2) in particular, the copper(II) iodide adduct is of the form [Cu(py)(4)I]I·2py, Cu on a site of mm2 symmetry in space group Cmcm, and five-coordinate (square-pyramidal), the same cationic species also being found in 2[Cu(py)(4)I](I(3))·[(py)(2)Cu(μ-I)(2)Cu(py)(2)] (structurally defined). Bromide or N-thiocyanate may be substituted for the unbound iodide ion in the solvated salt, resulting in complexes which crystallize in space group Ccca, but with both anions and the metal atom disordered. In [Cu(py)(4)(I(3))(2)], a pair of long Cu···I contacts approach a square-planar Cu(py)(4) array. Assignments of the ν(CuN) and ν(CuX) (X = Br, I, SCN) bands in the far-IR spectra are made, the latter with the aid of analogous assignments for [Cu(py)(2)X(2)] (X = Cl, Br), which show a dependence of ν(CuX) on the Cu-X bond length that is very similar to that determined previously for copper(i) halide complexes. The structure of the adventitious complex [(trans-)(H(2)O)(py)(4)CuClCu(py)(4)](I(3))(3)·H(2)O is also recorded, with six- and five-coordinate copper atoms; rational synthesis provides [{Cu(py)(4)}(2)(μ-Cl)](I(3))(3)·H(2)O with one water molecule less. In [{Cu(py)(4)Cl}((∞|∞))](I(3))·3py, square pyramidal [Cu(py)(4)Cl](+) cations, assisted by Cl···Cu interactions, stack to give rise to infinite polymeric strings. Several of these compounds were prepared mechanochemically, illustrating the applicability of this method to syntheses involving redox reactions as well as to complex syntheses involving up to five components. The totality of results demonstrates that the [Cu(II)(py)(4)] entity can be stabilized in an unexpectedly diverse range of mononuclear and multinuclear complexes through the presence of lattice pyridine molecules, the bulky triiodide ion, or a combination of both.

X-Ray Diffraction and μ-Raman Investigation of the Monoclinic-Orthorhombic Phase Transition in Th1−xUx(C2O4)2·2H2O Solid Solutions

A complete Th(1-x)U(x)(C(2)O(4))(2).2H(2)O solid solution was prepared by mild hydrothermal synthesis from a mixture of hydrochloric solutions containing cations and oxalic acid. The crystal structure has been solved from twinned single crystals for x = 0, 0.5, and 1 with monoclinic symmetry, space group C2/c, leading to unit cell parameters of a approximately 10.5 A, b approximately 8.5 A, and c approximately 9.6 A. The crystal structure consists of a two-dimensional arrangement of actinide centers connected through bis-bidentate oxalate ions forming squares. The actinide metal is coordinated by eight oxygen atoms from four oxalate entities and two water oxygen atoms forming a bicapped square antiprism. The connection between the layers is assumed by hydrogen bonds between the water molecules and the oxygen of oxalate of an adjacent layer. Under these conditions, the unit cell contains two independent oxalate ions. From high-temperature mu-Raman and X-ray diffraction studies, the compounds were found to undergo a transition to an orthorhombic form (space group Ccca). The major differences in the structural arrangement concern the symmetry of uranium, which decreases from C2 to D2, leading to a unique oxalate group. Consequently, the nu(s)(C-O) double band observed in the Raman spectra recorded at room temperature turned into a singlet. This transformation was then used to make the phase transition temperature more precise as a function of the uranium content of the sample.

Phase diagram of the Bi 2O 3–Cr 2O 3 system

Phase diagram of the pseudo-binary system Bi 2O 3–Cr 2O 3 has been reconstructed based upon X-ray diffraction measurement and differential thermal analysis. Four intermediate phases have been determined in this system: Bi 14CrO 24-based solid solution (β 1, space group I4/ m), Bi 10Cr 2O 21-based high-temperature solid solution (β 2, orthorhombic symmetry), a new compound Bi 2CrO 6 (X, monoclinic symmetry) and the stoichiometric compound Bi 6Cr 2O 15 (η phase, orthorhombic symmetry, space group Ccc2).

Solid-State Structures of 4-Carboxyphenylboronic Acid and Its Hydrates

Solid-state structures of 4-carboxyphenylboronic acid (1a) and its mono- and quarter-hydrates (1b and 1c, respectively) obtained by crystallization from different solvents, acetone, methanol, and 2-proponal, respectively, have been reported. In the anhydrous and monohydrate structures (1a and 1b), the H-atoms on the −B(OH)2 functional group exist in syn−syn conformation, but syn−anti conformation was found in the quarter-hydrate structure. While 1a and 1b crystallize through interactions between −B(OH)2 and −COOH groups (heteromeric), homomeric interactions of the functional groups (COOH···COOH and B(OH)2···B(OH)2) were observed in 1c. In addition, although similar interactions prevail in 1a and 1b, the latter crystallizes in a noncentrosymmetric space group Ccc2, registering itself as a unique structure with unusual catenation features with the aid of water molecules. However, 1a and 1c show many common features in the molecular arrangement in the crystal lattices with the formation of sheet structures.

On the Preparation of Coordination Polymers by Controlled Thermal Decomposition: Synthesis, Crystal Structures, and Thermal Properties of Zinc Halide Pyrazine Coordination Compounds

The five zinc(II) halide pyrazine coordination compounds poly-bis(mu2-pyrazine)-dichloro-zinc(II) (I), poly-(mu2-pyrazine-N,N')-dichloro-zinc(II) (II), poly-bis(mu2-pyrazine-N,N')-dibromo-zinc(II) (III), catena-(mu2-pyrazine-N,N')-dibromo-zinc(II) (IV), and catena-(mu-pyrazine)-diiodo-zinc(II) (V) were prepared by the reaction of ZnX2 (X = Cl, Br, I) with pyrazine in acetonitrile. In the crystal structure of compound I, the zinc atoms are coordinated by two chlorine atoms and two pyrazine ligands within distorted tetrahedra. The zinc atoms are linked by the N-donor ligands into layers. The crystal structure of compound III is very similar to that of compound I. The structure of compound III was originally reported in space group Ccca with similar a and b axes, but it was proved that the correct space group is I4/mmm. Ligand-poor compound V is isotypic to compound IV, in which ZnX2 units (X = Br, I) are connected by the pyrazine ligands into chains. It was originally reported in the noncentrosymmetric space group P2(1), but we found that the correct space group is P2(1)/m. If ligand-rich 1:2 compounds I and III are heated in a thermobalance, different mass steps are observed. We have proven that in the first step, ligand-poor compounds II and IV are formed in quantitative yields. On further heating, a second mass step occurs that leads to the formation of two new compounds of composition (ZnCl2)2(pyrazine) (VI) and (ZnBr2)2(pyrazine) (VII). However, the mass step is not well-resolved. and the new compounds are not phase-pure after the thermal event. If ligand-poor 1:1 compound V is investigated by thermogravimetry, a not-well-resolved single mass step is observed in which new ligand-poor 2:1 compound (ZnI2)2(pyrazine) (VIII) is formed. On further heating, all 2:1 compounds lose their remaining ligands and transform into the pure zinc(II) halides.

Preparation, crystal structure and chemical bonding analysis of the new binary compounds Rh 4Ga 21 and Rh 3Ga 16

The two new binary compounds Rh 4Ga 21 (space group Cmca ( Cmce), a = 40.135 ( 6 ) Å , b = 6.470 ( 2 ) Å , c = 6.473 ( 1 ) Å , Pearson symbol oC136) and Rh 3Ga 16 (space group Ccca ( Ccce), a = 30.424 ( 7 ) Å , b = 6.476 ( 2 ) Å , c = 6.468 ( 2 ) Å , Pearson symbol oC76) were synthesised and their crystal structures were solved from single-crystal X-ray diffraction data. From a topological point of view, both these two crystal structures and the crystal structure of PdGa 5 can be described either as inhomogeneous intergrowth structures containing three different kinds of segments, or as built up by layers of capped square antiprisms condensed via their capping atoms. Bonding analysis with bonding indicators revealed that the crystal structures of Rh 4Ga 21 and Rh 3Ga 16 have to be considered as framework polyanions formed by covalently bonded gallium atoms with embedded rhodium cations.

Calcium chlorite, Ca(ClO2)2, from X-ray powder diffraction data

The structure of calcium chlorite, Ca(ClO2)2, has been refined from X-ray powder diffraction data using the Rietveld method. The compound crystallizes in the ortho­rhom­bic space group Ccca (Ccce), with Z = 4. The structure is based on separate layers parallel to the ac plane, consisting of calcium cations that are coordinated by chlorite anions; the O atoms form almost ideal square antiprisms. Within the layers, each anion bridges four metal cations. The Ca atoms are located on special positions of 222 symmetry, the Cl atoms lie on twofold axes and the O atoms are in general positions. The compound is isostructural with strontium chlorite, Sr(ClO2)2, and lead chlorite, Pb(ClO2)2.

Strontium chlorite, Sr(ClO2)2, from X-ray powder diffraction data

The structure of strontium chlorite, Sr(ClO2)2, has been refined from X-ray powder diffraction data using the Rietveld method. The compound crystallizes in the ortho­rhom­bic space group Ccca (Ccce), with Z = 4. The structure is based on separate layers parallel to the ac plane, consisting of strontium cations that are coordinated by chlorite anions; the O atoms form almost ideal square antiprisms. Within the layers, each anion bridges four metal cations. The Sr atoms are located on special positions of 222 symmetry, the Cl atoms lie on twofold axes and the O atoms are in general positions. The compound is isostructural with calcium chlorite, Ca(ClO2)2, and lead chlorite, Pb(ClO2)2.

Vanadiocarpholite, Mn2+V3+Al(Si2O6)(OH)4, a new mineral from the Molinello mine, northern Apennines, Italy

Vanadiocarpholite, Mn2+V3+Al(Si2O6)(OH)4, occurs at the Molinello mine (Liguria, Italy) in mm-thick veins and in open fissures in a silicified wood sample from Mn-ore bearing cherts. Vanadiocarpholite is found as millimetric aggregates of acicular crystals associated with coatings and crystals of dark-green volborthite and quartz; rarely strongly elongated (001) pris- matic crystals up to 400 µm are also found. The crystals vary in colour from honey yellow-brown and brown (prismatic crystals) to pale straw-yellow (acicular crystal aggregates); they are brittle (prismatic crystals) to flexible (acicular crystals), transparent and non-fluorescent, with vitreous to silky lustre (prismatic crystals and acicular crystal aggregates, respectively) and nearly white streak; they show a perfect {010} cleavage; parting and twinning were not observed. The empirical formula of vanadiocarpholite, derived from microprobe analyses and structural refinement, approaches the ideal formula, Mn2+V3+Al(Si2O6)(OH)4; however, a wide compositional range is detected, mainly due to a solid solution with carpholite (V3+ vs Al substitution). X-ray single crystal data give the refined cell parameters a = 13.830(2) A, b = 20.681(3) A, c = 5.188(1) A and V = 1483.86 A3 in the space group Ccca. Micrometric crystals of vanadiocarpholite were also investigated by transmission and analytical electron microscopy. TEM analyses show a good agreement with WDS and XRD data, but disordered layer stacking sequences are observed. The crystal structure refinement indicates vanadiocarpholite to be isotypic with carpholite, therefore it belongs to the carpholite group together with carpholite, magnesiocarpholite, ferrocarpholite, balipholite and potassic-carpholite.

Preparation and crystal structural characterization of Cu(II) complex with piperidine-4-carboxylic acid

Copper(II) complex with piperidine-4-carboxylic acid (HPipe-4), Cu(HPipe-4)4(ClO4)2 (I) was prepared and characterized by IR, X-ray diffraction, and thermal analysis. The crystal is orthorhombic with space group Ccca, Z = 8, a =17.415(3) A, b =17.399(2) A, c = 21.426(3) A. The copper atom has a square surrounding and is coordinated by four carboxylato oxygen atoms in monodentate coordination mode. Full-matrix least-squares refinements gave a final R value of 0.0723 for 22169 reflections. The complex consists of two perpendicularly arranged molecules differing slightly in conformations and shows a three-dimensional polymeric structure formed by hydrogen bonds.

POTASSIC-CARPHOLITE, A NEW MINERAL SPECIES FROM THE SAWTOOTH BATHOLITH, BOISE COUNTY, IDAHO, U.S.A.

Potassic-carpholite, ideally (K,) (Li,Mn 2+ )2 Al4 Si4 O12 (OH)4 (F,OH)4, is a new mineral species from the Sawtooth batholith, an anorogenic Tertiary granite pluton near Centerville, Boise County, Idaho, U.S.A. It occurs as irregular tufts (up to 2 mm across) of radiating acicular-to-fibrous crystals in miarolitic cavities in the granite, associated with quartz, microcline, albite, beryl, topaz, bertrandite, hellandite, zinnwaldite, fluorite, hematite and apatite. Individual crystals of potassic-carpholite are white to straw yellow with a white streak and a vitreous luster, and are non-fluorescent in ultraviolet light. Crystals are generally 20‐40 m across and approximately 500 m long and elongate along [100]. Potassic-carpholite is brittle with an irregular fracture on ends of the acicular crystals, and has a perfect cleavage parallel to {010}. Twinning was not observed. The Mohs hardness is ~5, and the observed and calculated densities are 3.08(2) and 3.06 g/cm 3 , respectively. Potassic-carpholite is biaxial negative, with 1.578, 1.592, 1.598, all ±0.002, 2V(obs.) = 57(2)°, 2V(calc.) = 66°, weakly pleochroic with X pale yellow, Y = Z colorless, with X > Y, Z and X = b, Y = a and Z = c. Potassic-carpholite is orthorhombic, space group Ccca, a 13.715(5), b