2D-network of inorganic-organic hybrid material built on Keggin type polyoxometallate and amino acid: [L-C2H6NO2]3[(PO4)Mo12O36]·5H2O

A new inorganic-organic hybrid material based on polyoxometallate, [L-C₂H₆NO₂]₃[(PO₄)Mo₁₂O₃₆]·5H₂O, has been successfully synthesized and characterized by single-crystal X-ray analysis, elemental analysis, infrared and ultraviolet spectroscopy, proton nuclear magnetic resonance and differential thermal analysis techniques. The title compound crystallizes in the monoclinic space group, P2₁/c_, with a = 12.4938 (8) Å, b = 19.9326 (12) Å, c = 17.9270 (11) Å, β = 102.129 (1)°, V = 4364.8 (5) Å³, Z = 4 and R₁(wR₂) = 0.0513, 0.0877. The most remarkable structural feature of this hybrid can be described as two-dimensional inorganic infinite plane-like (2D/∞ [(PO₄)Mo₁₂O₃₆]³⁻) which forming via weak Van der Waals interactions along the z axis. The characteristic band of the Keggin anion [(PO₄)Mo₁₂O₃₆]³⁻ appears at 210 nm in the UV spectrum. Thermal analysis indicates that the Keggin anion skeleton begins to decompose at 520 °C.     

Reinvestigation of the binary diagram Na3PO4-FePO4 and crystal structure of a new iron phosphate Na3Fe3(PO4)4

A new iron(III) phosphate Na₃Fe₃(PO₄)₄ has been synthesized and characterized. It decomposes before melting at 860°C into FePO₄ and Na₃Fe₂(PO₄)₃. The structure of the compound was determined by single-crystal X-ray diffraction. The unit cell is monoclinic with the following parameters: a=19.601(8) Å, b=6.387(1) Å, c=10.575(6) Å and β=91.81(4)°; Z=4; space group: C2/c. Na₃Fe₃(PO₄)₄ exhibits a layered structure involving corner-linkage between FeO₆ octahedra, and corner- and edge-sharing between FeO₆ octahedra and PO₄ tetrahedra. The Na⁺ cations occupying the interlayer space are six- and seven-fold coordinated by oxygen atoms. The relationship between the structure of Na₃Fe₃(PO₄)₄ and the previous reported hydrate K₃Fe₃(PO₄)₄·H₂O will be discussed.     

Synthesis and crystal structure of a novel lithium bismuth phosphate, Li2Bi14.67(PO4)6O14

A lithium bismuth phosphate, Li₂Bi_14.67(PO₄)₆O₁₄, has been synthesized for the first time by the solid-state method. The crystal structure was determined by single crystal X-ray diffraction at 150 K. Li₂Bi_14.67(PO₄)₆O₁₄ crystallizes in the monoclinic system C2/c (No. 15), with a = 30.8189(4) Å, b = 5.2691(3) Å, c = 24.5302(3) Å, β = 122.84(2)°, V = 3346.81(1) Å³ and Z = 2. The structure along the b axis consists of layers of [Bi₂O₂] units as the basic building block. These are separated by isolated PO₄ and LiO₄ tetrahedra. The oxygen co-ordination around two of the phosphorus atoms is disordered. Solid-state ⁷Li NMR studies confirm the presence of lithium in the structure. The material shows ionic conductivity of the order of 10⁻⁵ S cm⁻¹ at 600 °C.     

Hydrothermal synthesis, structural and physico-chemical characterizations of two Nasicon phosphates: M0.50Ti2(PO4)3 (M = Mn, Co)

The family of titanium Nasicon-phosphates of generic formula M_0.5^IITi₂(PO₄)₃ has been revisited using hydrothermal techniques. Two phases have been synthesized: Mn_0.5^IITi₂(PO₄)₃ (MnTiP) and Co_0.5^IITi₂(PO₄)₃ (CoTiP). Single crystal diffraction studies show that they exhibit two different structural types. Mn_0.5^IITi₂(PO₄)₃ phosphate crystallizes in the R-3 space group, with the cell parameters a = 8.51300(10) Å and c = 21.0083(3) Å (V = 1318.52(3) Å³ and Z = 6). The Co_0.5^IITi₂(PO₄)₃ phosphate crystallizes in the R-3c space group, with a = 8.4608(9) Å and c = 21.174(2) Å (V = 1312.7(2) Å³ and Z = 6). These two compounds are clearly related to the parent Nasicon-type rhombohedral structure, which can be described using [Ti₂(PO₄)₃] framework composed of two [TiO₆] octahedral interlinked via three [PO₄] tetrahedra. ³¹P magic-angle spinning nuclear magnetic resonance (MAS-NMR) data are presented as supporting data. Curie-Weiss-type behavior is observed in the magnetic susceptibility. The phases are also characterized by IR spectroscopy and UV-visible.     

Synthesis, crystal structure and infrared study of LiEr(PO3)4

A single-crystal X-ray diffraction analysis has been performed on LiEr(PO₃)₄ prepared by the flux method. The compound crystallizes in the monoclinic system with space group C2/c and cell parameters: a = 16.262(2), b = 7.032(1), c = 9.549(2) Å and β = 125.95(1)°. The crystal structure was refined based on 1272 independent reflections with I > 2σ(I). Final values of the reliability factors were improven considerably: R(F²) = 0.0180 and wR(F²) = 0.0490. The LiEr(PO₃)₄ structure is characterized by infinite chains (PO₃)_n, extending parallel to the b direction. The ErO₈ dodecahedra and LiO₄ tetrahedra alternate on two-fold axes in the middle of four (PO₃)_n chains. The vibrational study by infrared absorption spectroscopy is reported.     

Synthesis, crystal structure and magnetic properties of a new lithium cobalt metaphosphate, LiCo(PO3)3

A new lithium cobalt metaphosphate, LiCo(PO₃)₃, is reported for the first time, which was discovered during the exploratory synthesis in Li-Co-P-O system by solid state reaction. The structure has been refined by powder X-ray Rietveld refinement method (P2₁2₁2₁, a = 8.5398(2) Å, b = 8.6326(2) Å and c = 8.3520(2) Å, Z = 4, R_p = 13.6%, R_wp = 19.4%, R_exp = 17.7%, S = 1.11, χ² = 1.23). It is isostructural with LiM(PO₃)₃ (M = Fe, Cu). It contains (PO₃)¹⁻ chains with the Co atoms localized in the octahedral sites, bridging four neighboring chains. The magnetic susceptibility measurement showed a typical paramagnetic behavior of high spin of Co²⁺, following the Curie-Weiss law in the temperature range of 5-300 K. Unlike the olivine type lithium cobalt phosphate, LiCoPO₄, cyclic voltammetry of LiCo(PO₃)₃ assembled in the coin-type cell showed no electrochemical activity in the voltage region of 1-5 V versus Li/Li⁺.     

Synthesis and characterization of a new monophosphate (5-Cl-2,4-(OCH3)2C6H2NH3)H2PO4

Chemical preparation, crystal structure and NMR spectroscopy of a new organic cation 5-chloro(2,4-dimethoxy)anilinium monophosphate H₂PO₄ are given. This new compound crystallizes in the monoclinic system, with the space group P2₁/c and the following parameters: a = 5.524(2) Å, b = 9.303(2) Å, c = 23.388(2) Å, β = 90.66(4), V = 1201.8(2) Å³, Z = 4 and D_x = 1.573 g cm⁻³. Crystal structure has been determined and refined to R = 0.031 and R_w = 0.080 using 1702 independent reflections. Structure can be described as an infinite (H₂PO₄)_nⁿ⁻ corrugated chains in the a-direction. The organic groups (5-Cl-2,4-(OCH₃)₂C₆H₂NH₃)⁺ are anchored between adjacent polyanions through multiple hydrogen bonds. This compound is also investigated by IR, thermal, and solid-state, ¹³C, ³¹P MAS NMR spectroscopies.     

Synthesis and crystal sructure of a new dihydrogenomonophosphate (4-C2H5C6H4NH3)H2PO4

Chemical preparation, crystal structure, calorimetric, and spectroscopic investigations are given for a new organic-cation dihydrogenomonophosphate, (4-C₂H₅C₆H₄NH₃)H₂PO₄ in the solid state. This compound crystallizes in the orthorhombic space group Pbca with the following unit cell parameters: a=8.286(3) Å, b=9.660(2) Å, c=24.876(4) Å, Z=8, V=1991.2(7) Å³, and D_X=1.442 g cm⁻³. Crystal structure was solved with a final R=0.054 for 3305 independent reflections. The atomic arrangement coaled described as H₂PO₄⁻ layers between which are located the 4-ethylanilinium cations.     

Preparation, structure and luminescent properties of a new potassium yttrium borate K3Y3(BO3)4

A new yttrium borate compound K₃Y₃(BO₃)₄ has been obtained in the K₂O-Y₂O₃-B₂O₃ ternary system. Its structure, determined from single crystal X-ray diffraction data, shows that it belongs to space group P2₁/c with unit cell dimensions of a = 10.4667(16) Å, b = 17.361(3) Å, c = 13.781(2) Å and β = 110.548(8)°. The structure consists sheets of [Y₈B₈O₂₄]_∞ linked by out of sheet BO₃ groups and Y ions to form a three-dimensional framework. The luminescent properties of Eu³⁺ and Tb³⁺ doped K₃Y₃(BO₃)₄ materials have also been studied.     

New lead vanadium phosphate with langbeinite-type structure: Pb1.5V2(PO4)3

The new lead vanadium phosphate Pb_1.5V₂(PO₄)₃ was synthesized by solid state reaction and characterized by X-ray powder diffraction, electron microscopy, and magnetic susceptibility measurements. The crystal structure of Pb_1.5V₂(PO₄)₃ (a = 9.78182(8) Å, S.G. P2₁3, Z = 4) was determined from X-ray powder diffraction data and belongs to the langbeinite-type structures. It is formed by corner-linked V³⁺O₆ octahedra and tetrahedral phosphate groups resulting in a three-dimensional framework. The lead atoms are situated in the structure interstices and only partially occupy their positions. An electron microscopy study confirmed the structure solution. Magnetic susceptibility measurements revealed Curie-Weiss (CW) behavior for Pb_1.5V₂(PO₄)₃ at high temperature whereas at around 14 K an abrupt increase on the susceptibility was observed.     

Phase transitions, structure and ion conductivity of zirconium hydrogen phosphates, H1±XZr2−XMX(PO4)3·H2O (M = Nb, Y)

Structure transformations and proton conductivity of hydrogen zirconium phosphates with the NASICON structure, H_1±XZr_2−XM_X(PO₄)₃·H₂O (X = 0, 0.02 and 0.1, M = Nb, Y), were studied by X-ray powder diffraction, calorimetry, IR- and impedance spectroscopy. Substitution of zirconium by niobium leads to decrease of the lattice parameters, while yttrium doping leads to their increase. H_0.9Zr_1.9Nb_0.1(PO₄)₃ structure was determined at 493 and 733 K. This phase crystallizes in rhombohedral space group with lattice parameters a = 8.8564(5) Å, c = 22.700(1) Å at 493 K and a = 8.8470(2) Å, c = 22.7141(9) Å at 733 K. The a parameter and lattice volume were found to decrease with temperature increasing. Structure transformations upon heating are caused mainly by the decrease of the M1 site and C cavities. Ion conductivity of obtained materials was found to increase in humid atmosphere. Activation energies of conductivity were calculated. Rhombohedral-triclinic phase transition found by X-ray powder diffraction was proved by calorimetry data. According to XRD and IR spectroscopy data hydrogen bond in HZr₂(PO₄)₃ was found to be weaker than in hydrated material.     

Synthesis and characterization of a new organic dihydrogenomonophosphate [3,5-(CH3O)2C6H3NH3]2(H2PO4)2

Chemical preparation, crystal structure, calorimetric studies and spectroscopic investigation are given for a new organic cation dihydrogenomonophosphate [3,5-(CH₃O)₂C₆H₃NH₃]₂(H₂PO₄)₂. This compound is triclinic with the following unit cell parameters: a=9.030(6) Å, b=16.124(5) Å, c=8.868(3) Å, α=75.04(3)°, β=110.71(4)°, γ=104.61(1)°, Z=4, V=1148.0(1) Å³, Z=2 and ρ_cal.=1.454 g cm⁻³. Crystal structure was solved and refined to R=0.04, 2752 independent reflections. The atomic arrangement can be described as inorganic layers of H₂PO₄⁻ anions parallel to planes, between which are located the organic groups. Solid-state and MAS-NMR spectroscopies are in agreement with the X-ray structure. Ab initio calculations allow the attribution of the phosphorous and carbon signals to the independent crystallographic sites and to the various atoms of the organic groups.     

Crystal growth and structure refinement of monoclinic Li2TiO3

Colorless platelet crystals of monoclinic Li₂TiO₃ with a maximum size of 5.0 mm × 5.0 mm × 0.5 mm were successfully grown by a flux method at 1373 K using a LiBO₂-Li₂O system flux. The stoichiometric chemical composition of Li₂TiO₃ was determined by the SEM-EDX, ICP-AES and density measurement using the single crystal samples. The thermal conductivity of the Li₂TiO₃ single crystals was evaluated using hot-disk method. A single-crystal X-ray diffraction study confirmed the monoclinic Li₂SnO₃-type structure, space group C2/c and the lattice parameters of a = 5.0623(5) Å, b = 8.7876(9) Å, c = 9.7533(15) Å, β = 100.212(11)°, and V = 427.01(9) Å³. The crystal structure was refined to the conventional values of R = 2.4% and wR=3.3% for 2187 independent observed reflections. The cationic arrangement of (LiTi₂) layers in Li₂TiO₃ was precisely revealed by the structure analysis.     

Co0.5TiOPO4: Crystal structure, magnetic and electrochemical properties

The new titanium oxyphosphate Co_0.5TiPO₅ has been prepared by solid state reaction. Its structure has been determined by single crystal X-ray diffraction and was further investigated by FT-IR spectroscopy and magnetic measurements. The compound crystallizes in the monoclinic system, S.G: P2₁/c [a = 7.358(1) Å, b = 7.378(2) Å, c = 7.383(3) Å, β = 119.66(3)°, Z = 4, R₁ = 0.0142, wR₂ = 0.0429]. The structure can be described as a network of very distorted TiO₆ octahedra, in which the Ti⁴⁺ ions are displaced from the centres of the octahedra, and slightly distorted PO₄ tetrahedra. Half of the octahedral cavities are occupied by Co atoms. The other half of octahedral sites is vacant and favourable for the electrochemical insertion of lithium. The insertion of lithium was studied by galvanostatic charging and discharging between different voltage limits.     

A new borophosphate chain anion in an organo-templated iron(III) borophosphate: Synthesis, crystal structure and magnetic properties of (C4H12N2)3Fe6(H2O)4[B6P12O50(OH)2]·2H2O

The organo-templated iron(III) borophosphate (C₄H₁₂N₂)₃Fe^III₆(H₂O)₄[B₆P₁₂O₅₀(OH)₂]·2H₂O was prepared under mild hydrothermal conditions (443 K). The crystal structure was determined from single-crystal X-ray data at 295 K (orthorhombic, Pbca (No. 61), Z=4, a=17.8023(7) Å, b=16.1037(5) Å, c=19.1232(6) Å, V=5482.3(3) Å³, R1=0.055, wR2=0.104, 6576 observed reflections with I>2σ(I)) and contains a new type of borophosphate anion: a mixed open- and loop-branched zehner single chain, , built from heptamers [B₂P₅O₂₁] interconnected by BO₃(OH) tetrahedra sharing their third oxygen corners with additional (terminal) PO₄ tetrahedra to form open branchings. The mixed open- and loop-branched single chains running along [0 0 1] are interconnected by three crystallographically independent iron coordination octahedra to form a 3D framework structure containing eight-membered ring channels running along [0 1 0] and cages, which are occupied by two crystallographically independent piperazine cations and H₂O molecules. The displacement parameters of C and N atoms in the piperazine cations are dramatically influenced by the strength of the hydrogen bond reflecting the shape of the cavities. The magnetic investigations indicate the existence of antiferromagnetic interactions as the major components. A narrow hysteresis at low temperatures indicates a weak ferromagnetic component, due to a non-cancellation of spins.     

Synthesis, structure refinement and characterisation of a new oxyphosphate Mg0.50TiO(PO4)

A new titanium oxyphosphate Mg_0.50TiO(PO₄) has been synthesized and characterized by several physical techniques: X-ray diffraction, ³¹P MAS-NMR, Raman diffusion, infrared absorption and diffuse reflectance spectroscopy. It crystallizes in the monoclinic system with unit cell parameters: a = 7.367(9), b = 7.385(8), c = 7.373(9) Å, β = 120.23(1), with the space group P2₁/c (no. 14), Z = 4. The crystal structure has been refined by the Rietveld method using X-ray powder diffraction. The conventional R indices obtained are R_wp = 0.138, R_p = 0.096 and R_B = 0.0459. The structure of Mg_0.50TiO(PO₄) consists of infinite chains of corner-shared [TiO₆] octahedra parallel to the c-axis, crosslinked by corner-shared [PO₄] tetrahedra. These infinite chains have alternating short (1.74 Å) and long (2.26 Å) TiO bonds and are similar to those found in titanium oxyphosphate M^II_0.50TiO(PO₄) (M²⁺ = Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺). The magnesium atom is located in an antiprism between two [TiO₆] octahedra. ³¹P MAS NMR showed only a single ³¹P resonance line, in a good agreement with the crystal structure. Raman and IR spectra show strong bands respectively at 765 and 815 cm⁻¹, attributed to the vibration of TiOTiO bonds in the infinite chains. The gap due to the Oxygen-Titanium(IV) charge transfer is 3.37 eV.     

Synthesis, structure and magnetic properties of a new iron phosphonate-oxalate with 3D framework: [Fe(O3PCH3)(C2O4)0.5(H2O)]

A new iron phosphonate-oxalate [Fe(O₃PCH₃)(C₂O₄)_0.5(H₂O)] (1), has been synthesized under hydrothermal condition. The single-crystal X-ray diffraction studies reveal that 1 consists of layers of vertex-linked FeO₆ octahedra and O₃PC tetrahedra, which are further connected by bis-chelate oxalate bridges, giving to a 3D structure with 10-membered channels. Crystal data: monoclinic, P2₁/n (no. 14), a = 4.851(2) Å, b = 16.803(7) Å, c = 7.941(4) Å, β = 107.516(6)°, V = 617.2(5) Å³, Z = 4, R₁ = 0.0337 and wR₂=0.0874 for 1251 reflections [I > 2σ(I)]. Mössbauer spectroscopy measurement confirms the existence of high-spin Fe(III) in 1. Magnetic studies show that 1 exhibits weak ferromagnetism with T_N = 30 K due to a weak spin canting.     

Synthesis and characterization of a layered chlorozincophosphate Zn(HPO4)Cl·[C4H10NO]

A chlorozincophosphate of the composition Zn(HPO₄)Cl·[C₄H₁₀NO] has been synthesised under mild condition water medium in the presence of morpholine as organic template. Its unit cell is monoclinic P2₁/a with parameters a = 8.655(6) Å, b = 9.302(5) Å, c = 12.180(5) Å, β = 101.10(4)°, Z = 4 and V = 962.1(9) Å³. The structure was determinated by single crystal X-ray diffraction. The structure involves a network of ZnO₃Cl and PO₃(OH) tetrahedra forming macroanionic inorganic layers with four- and eight-membered rings. Charge balance is achieved by the protonated amine which is trapped in the interlayers space and interacts with the organic framework through hydrogen bonding. Solid state ³¹P and ¹³C MAS-NMR spectroscopies are in agreement with the X-ray structure.     

Synthesis and crystal structure of triphosphate RbPrHP3O10

Crystals of RbPrHP₃O₁₀ have been grown by the flux technique and characterized by single-crystal X-ray diffraction. RbPrHP₃O₁₀ crystallizes in the triclinic space group with lattice parameters: a = 7.0655(5), b = 7.7791(4), c = 8.6828(6) Å, α = 74.074(3), β = 74.270(3), γ = 82.865(2)°, V = 441.09(5) ų, Z = 2. The crystal structure has been solved yielding a final R(F²) = 0.0443 and R_w(F²) = 0.1426 for 1955 independent reflections (F_o² ≥ 2σ(F_o²)). The structure of RbPrHP₃O₁₀ consists of PrO₈ polyhedra and P₃O₁₀⁵⁻ groups sharing oxygen atoms to form a two-dimensional framework; the PrO₈ polyhedra form infinite chains by edge-sharing. Each Rb⁺ ion is bonded to 10 oxygen atoms, these ions are located between chains formed of (HP₃O₁₀)⁴⁻. The energies of the vibrational modes of the crystal were obtained from measurements of the infrared spectrum.     

Phase relations of the Li2O-Ta2O5-B2O3 and Li2O-WO3-B2O3 systems and promising nonlinear optical compounds in K2O-Ta2O5-B2O3 system

The subsolidus phase equilibria of the Li₂O-Ta₂O₅-B₂O₃, K₂O-Ta₂O₅-B₂O₃ and Li₂O-WO₃-B₂O₃ systems have been investigated mainly by means of the powder X-ray diffraction method. Two ternary compounds, KTaB₂O₆ and K₃Ta₃B₂O₁₂ were confirmed in the system K₂O-Ta₂O₅-B₂O₃. Crystal structure of compound KTaB₂O₆ has been refined from X-ray powder diffraction data using the Rietveld method. The compound crystallizes in the orthorhombic, space group Pmn2₁ (No. 31), with lattice parameters a = 7.3253(4) Å, b = 3.8402(2) Å, c = 9.3040(5) Å, z = 2 and D_calc = 4.283 g/cm³. The powder second harmonic generation (SHG) coefficients of KTaB₂O₆ and K₃Ta₃B₂O₁₂ were five times and two times as large as that of KH₂PO₄ (KDP), respectively.