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At least 397 records · Page 22
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DOE OSTI2015

Oxygen trapped by rare earth tetrahedral clusters in Nd{sub 4}FeOS{sub 6}: Crystal structure, electronic structure, and magnetic properties

Single crystals of Nd{sub 4}FeOS{sub 6} were grown from an Fe–S eutectic solution. Single crystal X-ray diffraction analysis revealed a Nd{sub 4}MnOSe{sub 6}-type structure (P6{sub 3}mc, a=9.2693(1) Å, c=6.6650(1)Å, V=495.94(1) Å{sup 3}, Z=2), featuring parallel chains of face-sharing [FeS{sub 6×1/2}]{sup 4−} trigonal antiprisms and interlinked [Nd{sub 4}OS{sub 3}]{sup 4+} cubane-like clusters. Oxygen atoms were found to be trapped by Nd{sub 4} clusters in the [Nd{sub 4}OS{sub 3}]{sup 4{sub +}} chains. Structural differences among Nd{sub 4}MnOSe{sub 6}-type Nd{sub 4}FeOS{sub 6} and the related La{sub 3}CuSiS{sub 7}− and Pr{sub 8}CoGa{sub 3}-type structures have been described. Magnetic susceptibility measurements on Nd{sub 4}FeOS{sub 6} suggested the dominance of antiferromagnetic interactions at low temperature, but no magnetic ordering down to 2 K was observed. Spin-polarized electronic structure calculations revealed magnetic frustration with dominant antiferromagnetic interactions. - Graphical abstract: Trapping of oxygen in Nd{sub 4} tetrahedral clusters results in the formation of the Nd{sub 4}MnOSe{sub 6}-type Nd{sub 4}FeOS{sub 6}, in contrast to the La{sub 3}CuSiS{sub 7}-type oxygen-free Nd{sub 4}FeS{sub 7} and related Pr{sub 8}CoGa{sub 3}-type structures. Complex magnetic frustration inhibits magnetic ordering at low temperature. - Highlights: • Single crystals of Nd{sub 4}FeOS{sub 6} were grown using self-flux method. • Oxygen was found trapped by Nd{sub 4} tetrahedral clusters. • Comparison with two closely related structural types were discussed. • Magnetic measurements revealed antiferromagnetic (AFM) interaction. • VASP calculations confirmed strong magnetic frustration in AFM model.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Synthesis, structures and properties of two new chiral rare earth-organic frameworks constructed by L/D-tartaric acid

Hydrothermal reactions of rare earth cerium with L- or D- tartaric acid afford a pair of novel chiral enantiomer coordination polymers, namely, [Ce(L-tart)(CH{sub 2}OHCH{sub 2}OH)(H{sub 2}O)]Cl (L-1) and [Ce(D-tart)(CH{sub 2}OHCH{sub 2}OH)(H{sub 2}O)]Cl (D-1). Their structures were determined by single crystal X-ray diffraction analyses and further characterized by elemental analyses, XRD, IR spectra, and TG analyses. The circular dichroism (CD) spectra and second-harmonic generation (SHG) efficiency measurements proved that they are of structural chirality in the bulk samples. To the best of our knowledge, the enantiomers of L-1 and D-1 are the first 2D chiral dilayer frameworks constructed from L/D-tartrate ligands, ancillary ligand ethanediol and lanthanide ion Ce. - Graphical abstract: Hydrothermal reactions of rare earth cerium with L- or D- tartaric acid afford a pair of novel chiral enantiomer coordination polymers, namely, [Ce(L-tart)(CH{sub 2}OHCH{sub 2}OH)(H{sub 2}O)]Cl (L-1) and [Ce(D-tart)(CH{sub 2}OHCH{sub 2}OH)(H{sub 2}O)]Cl (D-1). Structural analysis indicates that the enantiomers of L-1 and D-1 are the first 2D chiral dilayer frameworks constructed from L/D-tartrate ligands and ancillary ligands ethanediol reacted with lanthanide ions Ce.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

RFe{sub 2}Mg{sub x}Al{sub 8−x} (R=La–Nd and Sm; x≈0.8): Flux synthesis, structure, magnetic and electrical properties

Single crystals of Mg-substituted CeFe{sub 2}Al{sub 8} type intermetallics RFe{sub 2}Mg{sub x}Al{sub 8–x} (R=La–Nd and Sm; x≤1) were grown by reacting iron and rare earth metals in 1:1 Mg/Al mixed flux. The structure features mono-capped and bi-capped trigonal prismatic FeAl{sub 6} units. Electronic structure calculations indicate that magnesium substitution reduces the valence electron count, shifting the Fermi level away from a pseudo-gap. This changes the electronic nature of the cerium analog; the previously reported ternary CeFe{sub 2}Al{sub 8} shows strong hybridization between the cerium states and the conduction electrons, resulting in no magnetic moment on Ce atoms. On the other hand, magnetic susceptibility measurements on CeFe{sub 2}Mg{sub x}Al{sub 8–x} indicates a localized moment on cerium. The newly synthesized Pr, Nd and Sm analogs exhibit antiferromagnetic ordering at 2.8 K, 7.8 K and 12 K respectively. Solid state {sup 27}Al NMR of LaFe{sub 2}Mg{sub x}Al{sub 8–x} exhibits a broad Knight shift at ~1200 ppm, consistent with the metallic behavior shown by electrical resistivity data. - Graphical abstract: Mg substitution into CeFe{sub 2}Al{sub 8} modifies cerium valence due to changing valence electron count. - Highlights: • RFe{sub 2}Mg{sub x}Al{sub 8−x} (R=La–Nd, Sm) grow as large crystals from reactions in Mg/Al flux. • Products are magnesium-substituted variants of CeFe{sub 2}Al{sub 8}, with CaCo{sub 2}Al{sub 8} structure. • Ce magnetic moment in CeFe{sub 2}Mg{sub x}Al{sub 8−x} varies from that in CeFe{sub 2}Al{sub 8} due to VEC change. • Antiferromagnetic ordering observed for Pr, Nd, Sm analogs of RFe{sub 2}Mg{sub x}Al{sub 8−x}.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Structure and physical properties of RE{sub 2}AgGe{sub 3} (RE=Ce, Pr, Nd) compounds

We have synthesized the compounds RE{sub 2}AgGe{sub 3} (RE =Ce, Pr, Nd) by arc melting. The crystal structure obtained from single crystal and powder X-ray diffraction suggests that these compounds crystallize in the α-ThSi{sub 2} structure type. The magnetic susceptibility data of Ce{sub 2}AgGe{sub 3} follows Curie–Weiss (CW) law above 25 K without any magnetic ordering down to 2 K. The effective magnetic moment (μ{sub eff}) was calculated as 2.53 μ{sub B}/Ce and negative Curie paramagnetic temperature (θ{sub p})=−2.4 K hint weak antiferromagnetic coupling among the adjacent spins. Pr{sub 2}AgGe{sub 3} shows a complex magnetic behavior wherein the magnetic susceptibility at field cooled and zero field cooled modes bifurcates at 11.5 K with the latter undergoing a cusp like maxima, probably due to weak ferromagnetic interaction. The θ{sub p} and μ{sub eff} obtained are 4 K and 4.33 μ{sub B}/Pr, respectively. Nd{sub 2}AgGe{sub 3} undergoes multiple magnetic transitions. Temperature dependent resistivity data reveals that three compounds are metallic in nature. - Graphical abstract: The compounds Ce{sub 2}AgGe{sub 3}, Pr{sub 2}AgGe{sub 3} and Nd{sub 2}AgGe{sub 3} have been synthesized by arc melting. X-ray diffraction suggests tetragonal α-ThSi{sub 2} type structure and diverse magnetic properties exhibited in the magnetic measurements. - Highlights: • Two new compounds Ce{sub 2}AgGe{sub 3}, Nd{sub 2}AgGe{sub 3} and known Pr{sub 2}AgGe{sub 3} synthesized by arc melting. • Crystal structure of the compounds derived from X-ray diffraction. • Ce{sub 2}AgGe{sub 3} and Pr{sub 2}AgGe{sub 3} exhibit antiferromagnetic ordering. • Nd{sub 2}AgGe{sub 3} shows multiple magnetic transition with ferrimagnetic like behavior.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Structure and ionic conductivity of well-aligned polycrystalline sodium titanogallate grown by reactive diffusion

We prepared the b-axis-oriented polycrystalline Na{sub 0.85}Ti{sub 0.51}Ga{sub 4.37}O{sub 8} (NTGO) embedded in Ga{sub 2}O{sub 3}-doped Na{sub 2}Ti{sub 4}O{sub 9} matrix using the reactive diffusion technique. When the sandwich-type Ga{sub 2}TiO{sub 5}/NaGaO{sub 2}/Ga{sub 2}TiO{sub 5} diffusion couple was heated at 1323 K for 24 h, the NTGO polycrystal was readily formed in the presence of a liquid phase. The resulting polycrystalline material was characterized by X-ray diffractometry, electron microscopy and impedance spectroscopy. We mechanically processed the annealed diffusion couple and obtained the thin-plate electrolyte consisting mostly of the grain-aligned NTGO polycrystal. The ionic conductivity (σ) of the electrolyte along the common b-axis direction steadily increased from 1.3×10{sup −4} to 7.3×10{sup −3} S/cm as the temperature increased from 573 to 1073 K. There was a slope change at ca. 792 K for the Arrhenius plot of σ; the activation energies were 0.39 eV above this temperature and 0.57 eV below it. The NTGO showed the crystal structure (space group C2/m) with substantial positional disordering of one of the two Ga sites. The Na{sup +} ions occupied ca. 43% of the Wyckoff position 4i site, the deficiency of which would contribute to the relatively high ionic conductivity along the b-axis. The reactive diffusion could be widely applicable as the novel technique to the preparation of grain-aligned ceramics of multi-component systems. - Graphical abstract: We have prepared the b-axis-oriented Na{sub 0.85}Ti{sub 0.51}Ga{sub 4.37}O{sub 8} polycrystal embedded in Ga{sub 2}O{sub 3}-doped Na{sub 2}Ti{sub 4}O{sub 9} matrix by the heat treatment of sandwich-type diffusion couple of Ga{sub 2}TiO{sub 5}/NaGaO{sub 2}/Ga{sub 2}TiO{sub 5}. The resulting Na{sub 0.85}Ti{sub 0.51}Ga{sub 4.37}O{sub 8} electrolyte showed the ionic conductivity ranging from 1.3×10{sup −4} S/cm at 573 K to 7.3×10{sup −3} S/cm at 1073 K. - Highlights: • The b-axis-oriented polycrystalline Na{sub 0.85}Ti{sub 0.51}Ga{sub 4.37}O{sub 8} is successfully prepared. • Crystal structure of Na{sub 0.85}Ti{sub 0.51}Ga{sub 4.37}O{sub 8} is determined by single-crystal XRD. • The polycrystal shows relatively high Na{sup +} ion conductivity along the common b-axis. • Reactive diffusion is successfully used for the preparation of grain-aligned ceramics.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

High-pressure crystallography and compression behavior of the alkali-scandium-germanate end-members LiScGe{sub 2}O{sub 6} and NaScGe{sub 2}O{sub 6}

Synthetic single-crystal samples of the monoclinic pyroxene-type compounds LiScGe{sub 2}O{sub 6} and NaScGe{sub 2}O{sub 6} have been investigated by means of in-situ high-pressure Raman spectroscopy and X-ray diffraction techniques. Crystal-structure investigations at hydrostatic high-pressure conditions were carried out in addition to 10{sup −4} GPa measurements using the diamond-anvil cell technique up to ∼9.5 GPa. Both samples, LiScGe{sub 2}O{sub 6} (space group P2{sub 1}/c, a=9.9999(8) Å, b=9.1040(2) Å, c=5.4610(2) Å, β=109.240(2)° at 10{sup −4} GPa) and NaScGe{sub 2}O{sub 6} (space group C2/c, a=10.1678(5) Å, b=9.1583(5) Å, c=5.5672(3) Å, β=107.257(3)° at 10{sup −4} GPa), did not undergo any compression-induced change of symmetry as confirmed by single-crystal diffraction patterns. Series of high-pressure Raman spectra confirm the absence of any symmetry-related structural phase transition with band positions shifting in a smooth fashion on increasing pressure. High-precision lattice parameters, as determined from X-ray diffraction profile analyzes, were used to monitor both the compressibilities of lattice directions and the evolution of the unit-cell volume with pressure. The experimental data was fitted using a third-order Birch–Murnaghan equation-of-state approach and parameterized fits yield V{sub 0}=469.60(11) Å{sup 3}, K{sub 0}=85.6(1.3) GPa and K′=5.9(4) for LiScGe{sub 2}O{sub 6} and V{sub 0}=495.95(19) Å{sup 3}, K{sub 0}=79(3) GPa and K′=3.9(1.1) for NaScGe{sub 2}O{sub 6}. The systematic comparison of volume properties and compression behavior shows that both pyroxene-type compounds follow established trend lines with similar slopes in comparing volumes versus bulk moduli, and confirm that the position of trend lines in this systematics describing variations with M1 critically depend on the type of M2 and T cations, independent on the space-group symmetry. - Graphical abstract: Polyhedral model of the LiScGe{sub 2}O{sub 6} crystal structure at 9.51 GPa. Red and blue: crystallographic distinctive germanium-tetrahedral chains; Green: scandium-octahedral chains; Purple: lithium atoms. - Highlights: • High-quality high-pressure data of previously uninvestigated germanate compounds. • Results confirmed through complementing sXRD with Raman spectroscopy. • Comparison and relation of high-pressure pyroxene-type compounds.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

A 3D chiral metal-organic framework based on left-handed helices containing 3-amino-1 H-1,2,4-triazole ligand

A chiral metal-organic framework, [Cu(atr)(OH)]·0.5H{sub 2}O·0.5en (1) (Hatr=3-amino-1 H-1,2,4-triazole, en=ethylenediamine), was constructed via diffusion reaction of the achiral Hatr ligand and CuSO{sub 4} as starting materials. Compound 1 crystallizes in the chiral space group P3{sub 2}21 and features a porous metal-organic framework with 44.1% solvent-accessible volume fabricated by left-handed helices with a pitch height of l{sub p}=10.442 Å. Six helices gather around in a cycle forming a large honeycomb channel with a 6.58 Å inner diameter. Cu(II) center and atr{sup ‒} ligand regarded as 3-connected nodes, compound 1 can be simplified to a 3-c uninodal (4.12{sup 2}) (qtz-h) topological network. A gradual decreasing in the magnetic moment depending on temperature decreasing indicates an antiferromagnetic interaction in 1. The powder XRD confirms the bulk sample is a single crystal pure phase, and the thermogravimetric analysis shows the thermal stability of 1 is up to ca. 240 °C. - Highlights: • The present 3D chiral MOF is built from achiral Hatr ligand. • Six left-handed helices gather into a honeycomb channel in chiral sp P3{sub 2}21. • Compound 1 shows a 3-c uninodal (4.12{sup 2}) or qtz-h topological network. • Compound 1 indicates an antiferromagnetic interaction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Series of coordination polymers based on 4-(5-sulfo-quinolin-8-yloxy) phthalate and bipyridinyl coligands: Structure diversity and properties

Reactions between later metal salts and conjugational N-hetrocyclic sulfonate/ carboxylic acid under the presence of bipyridyl auxiliary ligands afforded a series of manganese, nickel, zinc, silver, cadmium coordination polymers bearing with phenyl pendant arm attached to quinoline skeletons, and they have been characterized by elements analysis, thermogravimetry, infrared spectroscopy and single-crystal X-ray diffraction studying. The series of polymers show interesting structural diversity in coordination environment, dimensions and topologies. They are all built from 2-D networks constructed from metal cluster through sulfonate or carboxylate groups, as the secondary building unit (SBU). The thermalgravimetric analyses show that they display framework stabilities in solid state. Variable-temperature magnetic susceptibility studies reveal the existence of antiferromagnetic interactions between adjacent Mn (II) ions in 1, and ferromagnetic interactions between Ni(II) ions for 2, respectively. The photo-luminescence properties of 3-5 have also been investigated systemically. - Highlights: • A series of coordination polymers based on later transition metal ions have been obtained. • They contain conjugational N-hetrocyclic sulfonate-carboxylic acid and bipyridyl auxiliary ligands. • They have been characterized systemically. • They exhibit structure diversity and interesting properties.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13}: A new telluro-phosphate with S=1/2 Heisenberg chain

A new telluro-phosphate compound Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13} with S=1/2 Heisenberg chain has been successfully synthesized by solid state reaction and grown by flux method. Single crystal X-ray diffraction reveals that Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13} crystallizes into a monoclinic space group C2/c and cell parameters of a=17.647(3) Å, b=7.255(2) Å, c=9.191(2) Å and β=100.16 (3)°. In the structure of Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13}, one dimensional [CuTePO{sub 7}]{sup 3−} chains are formed by tetrahedral PO{sub 4} and trigonal bi-pyramidal TeO{sub 4} joining square planar CuO{sub 4} groups. Those [CuTePO{sub 7}]{sup 3−} chains are inter-connected by sharing one oxygen atom from the TeO{sub 4} group to form two dimensional layers. Magnetic susceptibility and specific heat measurements confirm that the title compound is a model one dimensional Heisenberg antiferromagnetic chain system. - Graphical abstract: Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13}, containing (CuTePO{sub 7}){sup 3−} chains formed by PO{sub 4} and TeO{sub 4} joining CuO{sub 4} groups, shows typical 1D Heisenberg antiferromagnetic chain model behavior as confirmed by magnetic measurements. - Highlights: • New telluro-phosphate Ba{sub 2}Cu{sub 2}Te{sub 2}P{sub 2}O{sub 13} has been grown. • It features layered structure composed of [CuTePO{sub 7}]{sup 3−} chains and TeO{sub 4} groups. • It shows the Heisenberg antiferromagnetic chain behavior. • It is transparent in the range of 1000–2500 nm with a UV absorption edge of 393 nm.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Synthesis, crystal structure and optical property of a novel metal chalcohalide: ZnHg{sub 3}Se{sub 2}Cl{sub 4}

A novel chalcohalide ZnHg{sub 3}Se{sub 2}Cl{sub 4} has been synthesized through a solid state method and structurally characterized by single-crystal X-ray diffraction. It crystallizes in the acentric space group Cmc2{sub 1} (No. 36) with cell parameters a=7.3262(8) Å, b=12.518(2) Å, c=11.3324(14) Å. The compound consists of 12-membered Hg{sub 6}Se{sub 6} rings edge-sharing with six neighbored rings to construct a 2D layered network and the ZnCl{sub 4} tetrahedra are sandwiched between layers. TG-DTA measurement shows that the compound is thermally stable up to 300 °C. The band gap of the crystal is about 2.23 eV, and the crystal exhibits a broad transparent range from 0.56 to 13.8 µm. - Highlights: • A novel chalcohalide ZnHg{sub 3}Se{sub 2}Cl{sub 4} was synthesized by a solid state method. • The structure contains 12-membered Hg{sub 6}Se{sub 6} rings and ZnCl{sub 4} tetrahedra. • The band gap of the as-prepared compound is about 2.23 eV.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Spectral, mechanical, thermal, optical and solid state parameters, of metal-organic bis(hydrogenmaleate)-CO(II) tetrahydrate crystal

Metal-organic bis(hydrogenmaleate)-Co(II) tetrahydrate single crystals have been grown by slow evaporation solution growth technique at room temperature. The crystal structure and the unit cell parameters were analyzed from the X-ray diffraction studies. Single-crystal X-ray diffraction analyses reveal that the grown crystal belongs to triclinic system with the space group P-1. Functional groups in bis(hydrogenmaleate)-Co(II) tetrahydrate were identified by Fourier transform infrared spectral analysis. The peak observed at 663 cm{sup −1} is assigned to the (Co–O) stretching vibrations. The optical transmission of the crystal was studied by UV–vis–NIR spectral analysis. The photoluminescence emission studies were carried out for the title compound in a wide wavelength range between 350 nm and 550 nm at 303 K. Mechanical strength was tested by Vickers microhardness test. The laser damage threshold value has been determined using Nd:YAG laser operating at 1064 nm. At various frequencies and temperatures the dielectric behavior of the material was investigated. Solid state parameters such as plasma energy, Penn gap, Fermi energy and electronic polarizability were evaluated. Photoconductivity measurements were carried out for the grown crystal in the presence of DC electric field at room temperature. Thermal stability and decomposition of the crystal were studied by TG–DTA. The weight loss of the title compound occurs in different steps. - Graphical abstract: Molecular structure of the bis(hydrogenmaleate)-Co(II) tetrahydrate drawn at 40% ellipsoid probability level. - Highlights: • Bis(hydrogenmaleate)-Co(II) tetrahydrate single crystal is grown by slow evaporation method. • Structural and optical properties were discussed. • The title complex crystal is thermally stable up to 91 °C. • Plasma energy, Fermi energy and electronic polarizability are evaluated. • It exhibits positive photoconductivity.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Crystal structures and compressibility of novel iron borides Fe{sub 2}B{sub 7} and Fe{sub x}B{sub 50} synthesized at high pressure and high temperature

We present here a detailed description of the crystal structures of novel iron borides, Fe{sub 2}B{sub 7} and Fe{sub x}B{sub 50} with various iron content (x=1.01(1), 1.04(1), 1.32(1)), synthesized at high pressures and high temperatures. As revealed by high-pressure single-crystal X-ray diffraction, the structure of Fe{sub 2}B{sub 7} possesses short incompressible B–B bonds, which make it as stiff as diamond in one crystallographic direction. The volume compressibility of Fe{sub 2}B{sub 7} (the bulk modulus K{sub 0}= 259(1.8) GPa, K{sub 0}′= 4 (fixed)) is even lower than that of FeB{sub 4} and comparable with that of MnB{sub 4}, known for high bulk moduli among 3d metal borides. Fe{sub x}B{sub 50} adopts the structure of the tetragonal δ-B, in which Fe atoms occupy an interstitial position. Fe{sub x}B{sub 50} does not show considerable anisotropy in the elastic behavior. - Graphical abstract: Crystal structures of novel iron borides, Fe{sub 2}B{sub 7} and Fe{sub x}B{sub 50} (x=1.01(1), 1.04(1), 1.32(1)). - Highlights: • Novel iron borides, Fe{sub 2}B{sub 7} and Fe{sub x}B{sub 50}, were synthesized under HPHT conditions. • Fe{sub 2}B{sub 7} has a unique orthorhombic structure (space group Pbam). • Fe{sub 2}B{sub 7} possesses short incompressible B–B bonds that results in high bulk modulus. • Fe{sub x}B{sub 50} adopts the structure of the tetragonal δ-B composed of B{sub 12} icosahedra. • In Fe{sub x}B{sub 50} intraicosahedral bonds are stiffer than intericosahedral ones.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Dye sensitized solar cell applications of CdTiO{sub 3}–TiO{sub 2} composite thin films deposited from single molecular complex

A heterobimetallic complex [Cd{sub 2}Ti{sub 4}(μ-O){sub 6}(TFA){sub 8}(THF){sub 6}]·1.5THF (1) (TFA=trifluoroacetato, THF=tetrahydrofuran) comprising of Cd:Ti (1:2) ratio was synthesized by a chemical reaction of cadmium (II) acetate with titanium (IV) isopropoxide and triflouroacetic acid in THF. The stoichiometry of (1) was recognized by single crystal X-ray diffraction, spectroscopic and elemental analyses. Thermal studies revealed that (1) neatly decomposes at 450 °C to furnish 1:1 ratio of cadmium titanate:titania composite oxides material. The thin films of CdTiO{sub 3}–TiO{sub 2} composite oxides were deposited at 550 °C on fluorine doped tin oxide coated conducting glass substrate in air ambient. The micro-structure, crystallinity, phase identification and chemical composition of microspherical architectured CdTiO{sub 3}–TiO{sub 2} composite thin film have been determined by scanning electron microscopy, X-ray diffraction, Raman spectroscopy and energy dispersive X-ray analysis. The scope of composite thin film having band gap of 3.1 eV was explored as photoanode for dye-sensitized solar cell application. - Graphical abstarct: Microspherical designed CdTiO{sub 3}–TiO{sub 2} composite oxides photoanode film has been fabricated from single source precursor [Cd{sub 2}Ti{sub 4}(μ-O){sub 6}(TFA){sub 8}(THF){sub 6}]·1.5THF via aerosol assisted chemical vapor deposition technique for dye sensitized solar cell application. - Highlights: • Synthesis and characterization of a heterobimetallic Cd–Ti complex. • Fabrication of CdTiO{sub 3}–TiO{sub 2} thin film photoelectrode. • Application as dye sensitized photoanode for solar application.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

High-pressure high-temperature crystal growth of equiatomic rare earth stannides RENiSn and REPdSn

The two series of equiatomic rare earth (RE) stannides RENiSn and REPdSn were systematically studied with respect to high-pressure modifications. The normal-pressure (NP) low-temperature (LT) modifications were synthesized by arc-melting and subsequently treated under high-pressure (P{sub max}=11.5 GPa) and high-temperature (T{sub max}=1570 K) conditions in a Walker-type multi-anvil press. The pressure and temperature conditions were systematically varied in order to improve the crystallization conditions. The new ZrNiAl-type high-pressure modifications HP-RENiSn (RE=Sc, Y, La, Gd–Lu) and HP-REPdSn (RE=Y, Sm–Dy) were obtained in 80 mg quantities, several of them in X-ray pure form. Some of the REPdSn stannides with the heavy rare earth elements show high-temperature (HT) modifications. The structures of HP-ScNiSn, HP-GdNiSn, HP-DyNiSn (both ZrNiAl-type), NP-YbNiSn, and HT-ErPdSn (both TiNiSi-type) were refined from single crystal diffractometer data, indicating full ordering of the transition metal and tin sites. TiNiSi-type NP-EuPdSn transforms to MgZn{sub 2}-type HP-EuPdSn: P6{sub 3}/mmc, a=588.5(2), c=917.0(3) pm, wR2=0.0769, 211 F{sup 2} values, 11 variables. The structure refinement indicated statistical occupancy of the palladium and tin sites on the tetrahedral network. The X-ray pure high-pressure phases were studied with respect to their magnetic properties. HP-YPdSn is a Pauli paramagnet. The susceptibility data of HP-TbNiSn, HP-DyNiSn, HP-GdPdSn, and HP-TbPdSn show experimental magnetic moments close to the free ion values of RE{sup 3+} and antiferromagnetic ordering at low temperature with the highest Néel temperature of 15.8 K for HP-TbPdSn. HP-SmPdSn shows the typical Van Vleck type behavior along with antiferromagnetic ordering at T{sub N}=5.1 K. HP-EuPdSn shows divalent europium and antiferromagnetic ordering at 8.9 K followed by a spin reorientation at 5.7 K. - Graphical abstract: Packing of the polyhedra in the high-pressure phase of EuPdSn. - Highlights: • High-pressure phases of the stannides RENiSn and REPdSn. • Crystal growth conditions. • Pressure- and temperature-driven phase transitions. • Magnetic properties.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Two new Co(II)-MOFs based on polymeric chain building units: Crystal structures, and magnetic properties

Two new Co(II) metal-organic frameworks, namely [Co{sub 2}(bpm)(H{sub 2}O){sub 3}(L)]{sub n} (1) and ([Co(bpe)(H{sub 2}O)(H{sub 2}L)]·(bpe){sub 0.5}·(H{sub 2}O)){sub n} (2), (H{sub 4}L=1,1′:2′,1″-terphenyl-3,3″,4′,5′-tetracarboxylic acid, bpm=bis(4-pyridyl)amine, bpe=1,2-bis(4-pyridyl)ethene), have been obtained under hydrothermal conditions. Both complexes 1 and 2 have been characterized by elemental analysis, IR spectra, single-crystal X-ray diffraction, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). Complexes 1 and 2 consist of 1D Co(II) chains bridging by carboxylate groups in syn-anti fashion. 1 shows a novel 3D tri-nodal (4,6,10)-connected net with a (3.4{sup 3}.5{sup 2}){sub 2}(3{sup 2}.4{sup 14}.5{sup 12}.6{sup 12}.7{sup 4}.8)(3{sup 2}.4{sup 2}.5{sup 5}.6{sup 4}.7{sup 2}) topology. While 2 exhibits a 2D sql layer. Magnetic susceptibility measurements indicate that both 1 and 2 show weak antiferromagnetic interactions between the adjacent Co(II) ions in 300–8 K for 1 and 300–16 K for 2, respectively, and then 2 also displays ferromagnetic coupling at lower temperatures. - Graphical abstract: Two Co(II) coordination polymers with similar metal chain bridging by carboxylates in syn-anti fashion have been synthesized. Both 1 and 2 show weak antiferromagnetic interactions in high temperature, and then 2 also displays ferromagnetic coupling at lower temperatures. - Highlights: • Two Co(II) coordination polymers with similar metal chain bridging by carboxylates. • A novel 3D (4,6,10)-connected net and a 2D sql layers. • A antiferromagnetic coupling at high temperature for 1 and 2. • A ferromagnetic coupling at lower temperature for 2.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

A novel second-order non-linear optical coordination polymer with three-fold interpenetrated CdSO{sub 4}-type network constructed by carboxylate–sulfonate ligands and strontium ions

A novel strontium carboxylate–sulfonate coordination polymer, [Sr(HSIP)(H{sub 2}O){sub 3}]{sub n·}nH{sub 2}O (1) (NaH{sub 2}SIP=5-sulfoisophthalic monosodium salt) has been synthesized by hydrothermal reaction. It was characterized by X-ray single crystal diffraction, infrared spectroscopy, elemental and thermogravimetric analysis. Each strontium atom is eight-coordinate with a distorted bicapped trigonal prismatic arrangement. The whole HSIP{sup 2−} ligand acts as a η{sup 5}μ{sup 4} bridge to generate three-fold interpenetrated CdSO{sub 4}-type network structure, which is constructed from the left- and right-handed helixes paralleled to each other bridged by the HSIP{sup 2−} ligands. The luminescence spectrum indicates an emission maximum at 459 nm. Compound 1 shows a second harmonic generation (SHG) response that is 4 times that of KH{sub 2}PO{sub 4}. - Graphical abstract: The whole HSIP{sup 2−} ligands act as η{sup 5}μ{sup 4} bridges with strontium ions, and the strontium ion is eight-coordinated, showing a distorted bicapped trigonal prism geometry. - Highlights: • A novel coordination polymer with a CdSO{sub 4}-type network structure was synthesized. • It shows a second harmonic generation response that is 4 times that of KH{sub 2}PO{sub 4}. • It is constructed from the helixes paralleled to each other.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Hydrothermal crystal growth, piezoelectricity, and triboluminescence of KNaNbOF{sub 5}

Single crystals of the noncentrosymmetric KNaNbOF{sub 5} polymorph were grown for piezoelectric and triboluminescent measurements. Piezoelectric measurements yielded a d{sub 33} value of ±6.3 pCN{sup −1} and an effective electromechanical coupling coefficient of up to 0.1565 in the frequency range 1960–2080 kHz. Crystals of KNaNbOF{sub 5} were found to exhibit a strong triboluminscence effect visible to the naked eye as blue sparks when crystals are crushed. This triboluminescence effect is uncommon in that it is likely independent from both the piezoelectric effect and atmospheric electrical discharge. Instead, triboluminescence may originate from crystal defects or be related to an electroluminescence effect. - Graphical abstract: An optical emission visible to the naked eye as blue sparks is observed when KNaNbOF{sub 5} single crystals are fractured. - Highlights: • Single crystals of KNaNbOF{sub 5} were grown under hydrothermal conditions. • Piezoelectric and triboluminescent properties were characterized. • Piezoelectric measurements yielded a d{sub 33} value of ±pCN{sup −1}. • KNaNbOF{sub 5} exhibits strong triboluminscence visible to the naked eye as blue sparks.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Structure and magnetic properties of the REAuBi{sub 2} (RE=La–Nd, Sm) phases

We present the crystal structures and basic magnetic properties of the REAuBi{sub 2} (RE=La–Nd, Sm) compounds. This isostructural family crystallizes in the tetragonal P4/nmm (no. 129) HfCuSi{sub 2}-type, as determined by single crystal X-ray diffraction. Three distinct substructures are present: an RE layer, a tetrahedral AuBi layer, and a Bi square net layer. Electronic structure calculations indicate that these compounds display bands which cross the Fermi level, derived from both the Bi square net and the covalent AuBi layer. The small size of LaAuBi{sub 2} crystals precluded detailed physical property measurements, whereas large single crystals could be grown for all other phases investigated here. Single crystal measurements of CeAuBi{sub 2}, PrAuBi{sub 2}, and NdAuBi{sub 2} show overall antiferromagnetic ordering and decreasing magnetic anisotropy with decreasing rare earth size. SmAuBi{sub 2} also shows signatures of magnetic ordering. - Graphical abstract: The crystal structures and basic electronic and magnetic properties of the five REAuBi{sub 2} (RE=La–Nd, Sm) phases are presented. These tetragonal structures have alternating layers of AuBi{sub 4} tetrahedra and a Bi square net balanced by RE cations. Measurements performed on single crystals show strong magnetic anisotropy for CeAuBi{sub 2} and PrAuBi{sub 2} and weak anisotropy for NdAuBi{sub 2}. SmAuBi{sub 2} is weakly magnetic. - Highlights: • We present the structures and basic properties of single crystals of the new, tetragonal REAuBi{sub 2} (RE=La–Nd, Sm) phases. • CeAuBi{sub 2}, PrAuBi{sub 2}, NdAuBi{sub 2}, and SmAuBi{sub 2} order magnetically. • CeAuBi{sub 2} and PrAuBi{sub 2} display magnetic anisotropy. • CeAuBi{sub 2} appears analogous to CeAuSb{sub 2} and may be worthy of further study as a potential system for quantum criticality.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗