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DOE OSTI2014

Synthesis and characterization of ASnF{sub 3} (A=Na{sup +}, K{sup +}, Rb{sup +}, Cs{sup +})

A family of alkali metal tin(II) fluorides, ASnF{sub 3} (A=Na{sup +}, K{sup +}, Rb{sup +}, or Cs{sup +}), has been synthesized through a low temperature solvothermal technique. A fluorine free solvent, methanol, was used in the synthesis. NaSnF{sub 3}, KSnF{sub 3}, and RbSnF{sub 3} have been reported previously; however for RbSnF{sub 3} the reported space group is incorrect. CsSnF{sub 3} is a new alkali tin(II) fluoride, and exhibits a ‘zero-dimensional’ crystal structure with isolated SnF{sub 3}{sup −} anions separated by Cs{sup +} cations. In addition to the synthesis, infrared, UV–vis, thermogravimetric and differential thermal analysis measurements were performed. - Graphical abstract: Ball-and-stick diagrams of CsSnF{sub 3}. Display Omitted - Highlights: • A family of ASnF{sub 3} (A=Na{sup +}, K{sup +}, Rb{sup +} or Cs{sup +}) has been synthesized solvothermally at low temperatures. • Fluorine-free solvent, methanol, was used instead of conventional fluorinating agents. • RbSnF{sub 3} described in the correct space group exhibits infinite chains of corner-sharing SnF{sub 4} polyhedra. • New CsSnF{sub 3} exhibits a ‘zero-dimensional’ crystal structure consisting of isolated SnF{sub 3}{sup −} anionic polyhedra.

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DOE OSTI2014

Synthesis and characterization of novel barium iron phosphates: Insight into new structure types tailored by hydrogen atoms

A significant gap in our knowledge of phosphate crystal chemistry is the lack of understanding of what controls the depolymerization of [PO{sub 4}] tetrahedra. A new route using phosphoric acid without any added water at 240 °C has been developed to synthesize two new compounds Ba{sub 2}Fe{sub 2}[H(PO{sub 3}OH){sub 2}][H(P{sub 2}O{sub 7}){sub 2}] and Ba{sub 2}Fe[H(P{sub 2}O{sub 7}){sub 2}], as well as a new polymorph β-BaFe{sub 2}(P{sub 2}O{sub 7}){sub 2} from annealing the former at ≥500 °C. Structural characterizations show that Ba{sub 2}Fe{sub 2}[H(PO{sub 3}OH){sub 2}][H(P{sub 2}O{sub 7}){sub 2}] features a novel 2D {sup 2}{sub ∞}([Fe{sub 2}[H(PO{sub 3}OH){sub 2}][H(P{sub 2}O{sub 7}){sub 2}]]{sup 4−}) layer structure containing both hydrogen-diphosphate [H(P{sub 2}O{sub 7}){sub 2}] and hydrogen-monophosphate [H(PO{sub 3}OH){sub 2}] groups, whereas Ba{sub 2}Fe[H(P{sub 2}O{sub 7}){sub 2}] and β-BaFe{sub 2}(P{sub 2}O{sub 7}){sub 2} possess an 1D chain structure and a 3D framework structure, respectively. These structures support a control of hydrogen on the depolymerization of [PO{sub 4}] groups and our work opens a new way for the synthesis of other novel phosphates using controlled water activities. - Graphical abstract: A new route of controlled water activities led to syntheses of three new compounds, indicating water plays a crucial role in the formation of novel phosphates. - Highlights: • A new mild thermal route for the synthesis of novel phosphates. • Water activities controlling the reaction: 2H{sub 3}PO{sub 4}↔H{sub 4}P{sub 2}O{sub 7}+H{sub 2}O. • Phosphate with mixed hydrogen-monophosphate and diphosphate groups. • H atoms in the structural backbone affect the depolymerization of PO{sub 4} groups.

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DOE OSTI2014

Influence of calcination parameters on the synthesis of N-doped TiO{sub 2} by the polymeric precursors method

In this paper, the influence of calcination parameters on the synthesis of N:TiO{sub 2} catalysts obtained through the polymeric precursors method was evaluated. The powders were prepared by annealing Ti{sup 4+} precursor resins at different temperature-time conditions in air, resulting in powders with different degrees of crystallinity for N doping, which was done by adding urea to the as-prepared powders and calcining in N{sub 2} atmosphere. The N doping process resulted in band gap narrowing of TiO{sub 2} and, varying annealing temperature and time, can be an alternative method for preferential formation of substitutional N or interstitial N. It was found that the percentage of interstitial N increased with an increase in annealing temperature, resulting in the complete absence of substitutional N at 400 °C. The photocatalytic performance of the powders was evaluated using Rhodamine-B and Atrazine solutions under ultraviolet and visible irradiations. The coefficients revealed that interstitial N had a positive correlation to both ultraviolet and visible photoactivity. In contrast, substitutional N showed a negative correlation. Further, the ratio of substitutional N to interstitial N indicated a strong negative correlation to ultraviolet light photoactivity and no correlation to visible light photoactivity. However, substitutional N should be controlled for better photocatalytic properties. - Graphical abstract: The temperature influences to promote higher quantities of Interstitial N doped TiO{sub 2} than Substitutional and due to difference between energies levels for substitutional N doped TiO{sub 2} and Interstitial N doped TiO{sub 2}, it is presented difference on photocatalytic activity. - Highlights: • Temperature and time of synthesis of N doping TiO{sub 2} could affect the type of N (interstitial and substitutional N). • The percentage of interstitial N increased with an increase in annealing temperature. • Interstitial N improves ultraviolet and visible light degradation of color and colorless substrates (Rhod and Atraz). • Visible photoactivity may not depend only on band gap narrowing but on several factors.

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DOE OSTI2014

Synthesis, crystal structure, and electrical and magnetic properties of BaMo{sub 6}Te{sub 6}: A novel reduced molybdenum telluride containing infinite chains of trans-face shared Mo{sub 6} octahedra

Powder samples and single crystals of the new ternary compound BaMo{sub 6}Te{sub 6} were obtained by solid state reaction. The structure was determined by single-crystal X-ray diffraction. BaMo{sub 6}Te{sub 6} crystallizes in the hexagonal space group P6{sub 3}/m (No. 176) with unit-cell parameters a=9.3941(2) Å, c=4.5848(1) Å and Z=1. Full-matrix least-squares refinement on F{sup 2} using 452 independent reflections for 17 refinable parameters resulted in R1=0.0208 and wR2=0.0539. The structure consists of one-dimensional infinite chains of trans-face shared Mo{sub 6} octahedra capped by Se atoms. These chains that are running along the c axis are separated from each other by nine-coordinate Ba atoms. Resistivity measurements on a single crystal indicated that the BaMo{sub 6}Te{sub 6} compound is metallic down to 160 K and semiconductor below. Magnetic susceptibility measurements showed that BaMo{sub 6}Te{sub 6} is weakly diamagnetic with no anomaly at the metal–semiconductor transition. - Graphical abstract: We present here the synthesis, the crystal structure, and the electrical and magnetic properties of the new compound BaMo{sub 6}Te{sub 6} containing infinite chains of trans-face shared Mo{sub 6} octahedra. - Highlights: • BaMo{sub 6}Te{sub 6} contains infinite chains of trans-face-sharing Mo{sub 6} octahedra |Mo{sub 6/2}|{sub ∞}{sup 1}. • Synthesis by solid state reaction. • Single-crystal X-ray study. • Continuous metal–nonmetal transition. • Anderson localization.

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DOE OSTI2015

Synthesis, X-ray crystal structure, optical properties and DFT studies of a new 2D layered iodide bridged Pb(II) coordination polymer with 2,3-bis(2-pyridyl)pyrazine

The synthesis of two dimensional (2D) coordination polymer [Pb{sub 2}(µ-I){sub 2}(µ-dpp-N,N,N,N)(µ-dpp-N,N)I{sub 2}]{sub n} (dpp=2,3-bis(2-pyridyl)pyrazine) is reported. As determined by X-ray diffraction of a twinned crystal, the dpp ligand simultaneously adopts a bis–bidentate and bis–monodentate coordination mode in the crystal structure of compound. The electronic band structure along with density of states (DOS) calculated by the DFT method indicates that the compound is an indirect band gap semiconductor. According to the DFT calculations, the observed emission of the compound at 600 nm in solid phase could be attributed to arise from an excited LLCT state (dpp-π{sup ⁎} [C-2p and N-2p states, CBs] to I-6p state [VBs]). The linear optical properties of the compound are also calculated by DFT method. The structure of the compound in solution phase is discussed based on the measured {sup 1}H NMR and fluorescence spectra in DMSO. TGA studies indicate that the compound is thermally stable up to 210 °C. - Graphical abstract: The synthesis, crystal structure and emission spectra of [Pb{sub 2}(µ-I){sub 2}(µ-dpp-N,N,N,N)(µ-dpp-N,N)I{sub 2}]{sub n} is presented. The electronic band structure and linear optical properties of the compound are calculated by the DFT method. - Highlights: • Two dimensional [Pb{sub 2}(µ-I){sub 2}(µ-dpp-N,N,N,N)(µ-dpp-N,N)I{sub 2}]{sub n} has been prepared. • The structure of the compound is determined by XRD of a twinned crystal. • DFT calculations indicate that the compound is an indirect band gap semiconductor. • As shown by DFT calculations, the emission band of the compound is LLCT. • Solution phase structure of compound is explored by {sup 1}H NMR and emission spectra.

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DOE OSTI2015

Synthesis and characterization of pure STW-zeotype germanosilicate, Cu- and Co-substituted STW-zeotype materials

Pure STW-type germanosilicate (denoted as GeSi-STW), Cu- and Co-containing STW-zeotype (denoted as Cu-STW and Co-STW) materials were synthesized by the hydrothermal method in the presence of an organic structure-directing agent (OSDA), N,N-diethylethylenediamine (DEEDA). The effects of the reaction mixture ratio and the incorporation of transition metals M (M=Cu and Co) on the synthesis of the pure product was investigated. The synthesized samples were characterized by powder and single-crystal X-ray diffraction (XRD), scanning electron microscopy (SEM), inductively coupled plasma analysis (ICP), thermogravimetric and differential scanning calorimetry (TG–DSC) analysis and UV–vis diffuse reflectance spectra (DRS). The results reveal that the crystallization time, the concentration of H{sub 2}O in the reaction mixture and the addition of HF all have an important impact on the synthesis of pure STW-type zeolite. GeSi-STW is stable up to 800 °C, and has much higher thermal stability than SU-32 (stable to 400 °C). Co and Cu have been introduced for the first time into STW-zeotype materials. - Graphical abstract: SEM images of GeSi-STW (A and B), Co-STW (C and D) and Cu-STW (E and F). - Highlights: • Pure STW-type germanosilicate materials were hydrothermally synthesized. • The STW-type germanosilicate has high thermal stability up to 800 °C. • Co and Cu have been introduced for the first time in the STW-zeotype materials.

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DOE OSTI2015

Hydrothermal synthesis of zinc(II)-phosphonate coordination polymers with different dimensionality (0D, 2D, 3D) and dimensionality change in the solid phase (0D→3D) induced by temperature

Three new zinc(II) coordination polymers, [Zn(HO{sub 3}PCH{sub 2}CH{sub 2}COO)(C{sub 12}H{sub 8}N{sub 2})(H{sub 2}O)] (1), [Zn{sub 3}(O{sub 3}PCH{sub 2}CH{sub 2}COO){sub 2}(C{sub 12}H{sub 8}N{sub 2})](H{sub 2}O){sub 3.40} (2) and [Zn{sub 5}(HO{sub 3}PCH{sub 2}CH{sub 2}COO){sub 2}(O{sub 3}PCH{sub 2}CH{sub 2}COO){sub 2}(C{sub 12}H{sub 8}N{sub 2}){sub 4}](H{sub 2}O){sub 0.32} (3), with different structural dimensionality (0D, 2D and 3D, respectively) have been prepared by hydrothermal synthesis, and their structures were determined by single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic system (P2{sub 1}/c) forming discrete dimeric units bonded through H-bonds, while compounds 2 and 3 crystallize in the triclinic (P−1) and the monoclinic (C2/c) systems, respectively. Compound 3, showing three different coordination numbers (4, 5 and 6) for the zinc atoms, has also been obtained by thermal treatment of 1 (probed by high-temperature XRPD experiments). The crystalline features of these compounds, related to the coordination environments for the zinc atoms in each structure, provoke the increase of the relative fluorescence for 2 and 3, compared to the free phenanthroline. Thermal analysis (TG and DSC) and XPS studies have been also carried out for all compounds. - Graphical abstract: Three new coordination compounds of zinc with 2-carboxyethylphosphonic acid (H{sub 2}PPA) and phenanthroline have been obtained by hydrothermal synthesis. The crystalline structure depends on the different coordination environments of the zinc atoms (see two comparative Zn{sub 6}-moieties). The influence of the different coordination modes of H{sub 2}PPA with the central atom in all structures have been studied, being found new coordination modes for this ligand. Several compounds show a significant increase in relative fluorescence with respect to the free phenanthroline. - Highlights: • Compounds have been obtained modifying the reaction time and the rate of reagents. • Dimensionality and crystalline structure is a function of the zinc environments. • New coordination modes for 2-carboxyethylphosphonic acid are reported. • 3D-compound presents three different coordination environments for the zinc atoms. • Fluorescence properties are related to the structural dimensionality.

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DOE OSTI2015

Hydrothermal synthesis and characterization of a two-dimensional piperazinium cobalt–zinc phosphate via a metastable one-dimensional phase

A two-dimensional piperazinium cobalt–zinc phosphate, formulated as (C{sub 4}N{sub 2}H{sub 12}){sub 1.5}(Co{sub 0.6}Zn{sub 0.4}){sub 2}(HPO{sub 4}){sub 2}(PO{sub 4})·H{sub 2}O (2D), was synthesized under hydrothermal conditions. The crystal structure was determined using single-crystal X-ray diffraction data (monoclinic P2{sub 1}/c, a=8.1165(3) Å, b=26.2301(10) Å, c=8.3595(4) Å, and β=110.930(5)°) and the hydrogen atom positions were optimized by DFT calculations. A single-crystal corresponding to one-dimensional metastable phase, (C{sub 4}N{sub 2}H{sub 12})Co{sub 0.3}Zn{sub 0.7}(HPO{sub 4}){sub 2}·H{sub 2}O (1D), was also isolated and the crystal structure was determined (monoclinic P2{sub 1}/c, a=8.9120(6) Å, b=14.0290(1) Å, c=12.2494(5) Å, and β=130.884(6)°). The bulk was characterized by chemical (C–H–N) analysis, powder X-ray diffraction (PXRD), powder X-ray thermodiffractometry (HT-XRD), transmission electron microscopy (STEM(DF)-EDX and EFTEM), and thermal analysis (TG/SDTA-MS), including activation energy data of its thermal decomposition. The magnetic susceptibility and magnetization measurements show no magnetic ordering down to 4 K. - Graphical abstract: Hydrothermal synthesis and structural characterization of a two-dimensional piperazinium cobalt–zinc phosphate, (C{sub 4}N{sub 2}H{sub 12}){sub 1.5}(Co{sub 0.6}Zn{sub 0.4}){sub 2}(HPO{sub 4}){sub 2}(PO{sub 4})·H{sub 2}O (2D), have been reported. The crystal structure of a one-dimensional piperazinium cobalt–zinc phosphate, (C{sub 4}N{sub 2}H{sub 12})Co{sub 0.3}Zn{sub 0.7}(HPO{sub 4}){sub 2}·H{sub 2}O (1D) a metastable phase during the hydrothermal synthesis, was also determined. The thermal behavior of 2D compound is strongly dependent on the selected heating rate and the magnetic susceptibility and magnetization measurements show no magnetic ordering down to 4 K. - Highlights: • A 2D piperazinium cobalt–zinc phosphate has been synthesized and characterized. • Crystal structure of 1D metastable phase was also determined. • Thermal behavior of 2D compound is strongly dependent on the selected heating rate. • Magnetic measurements show no magnetic ordering down to 4 K.

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DOE OSTI2015

Synthesis, characterization and alloying of Cu{sub 2}ZnSnQ{sub 4} (Q=S, Se and Te) nanocrystals

Cu{sub 2}ZnSnQ{sub 4} nanocrystals, with Q=S, Se and Te, were grown by a colloidal synthetic approach and characterized by X-ray diffraction, transmission electron microscopy, and optical absorbance. We also demonstrate that doping and alloying at the nanoscale is possible by this approach. The results are discussed in terms of developing a standardized synthetic approach for the synthesis of quaternary nanocrystals, including doping and alloying, in order to allow for bottom-up processing of these materials for energy-related applications. - Graphical abstract: We developed a standardized synthetic approach for the synthesis of quaternary stannite Cu{sub 2}ZnSnQ{sub 4} nanocrystals with Q=S, Se and Te including doping, alloying and Te-based compositions for the first time, in order to allow for bottom-up processing of these materials for energy-related applications. - Highlights: • Cu{sub 2}ZnSnQ{sub 4} nanocrystals, with Q=S, Se and Te, were grown by a colloidal synthetic approach. • Doping and alloying of these quaternary nanocrystals were demonstrated for the first time. • This standardized synthetic approach allows for bottom-up processing of these materials for energy-related applications.

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DOE OSTI2015

Comparative XRPD and XAS study of the impact of the synthesis process on the electronic and structural environments of uranium–americium mixed oxides

Uranium–americium mixed oxides are potential compounds to reduce americium inventory in nuclear waste via a partitioning and transmutation strategy. A thorough assessment of the oxygen-to-metal ratio is paramount in such materials as it determines the important underlying electronic structure and phase relations, affecting both thermal conductivity of the material and its interaction with the cladding and coolant. In 2011, various XAS experiments on U{sub 1−x}Am{sub x}O{sub 2±δ} samples prepared by different synthesis methods have reported contradictory results on the charge distribution of U and Am. This work alleviates this discrepancy. The XAS results confirm that, independently of the synthesis process, the reductive sintering of U{sub 1−x}Am{sub x}O{sub 2±δ} leads to the formation of similar fluorite solid solution indicating the presence of Am{sup +III} and U{sup +V} in equimolar proportions. - Graphical abstract: Formation of (U{sup IV/V},Am{sup III})O{sup 2} solid solution by sol–gel and by powder metallurgy. - Highlights: • Uranium–americium mixed oxides were synthesized by sol–gel and powder metallurgy. • Fluorite solid solutions with similar local environment have been obtained. • U{sup V} and Am{sup III} are formed in equimolar proportions.

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DOE OSTI2015

Kinetic control in the synthesis of metastable polymorphs: Bixbyite-to-Rh{sub 2}O{sub 3}(II)-to-corundum transition in In{sub 2}O{sub 3}

An example for kinetic control of a solid-state phase transformation, in which the system evolves via the path with the lowest activation barrier rather than ending in the thermodynamically most favorable state, has been demonstrated. As a case study, the phase transitions of indium sesquioxide (In{sub 2}O{sub 3}) have been guided by theoretical calculations and followed in situ under high-pressure high-temperature conditions in multi-anvil assemblies. The corundum-type rh-In{sub 2}O{sub 3} has been synthesized from stable bixbyite-type c-In{sub 2}O{sub 3} in two steps: first generating orthorhombic Rh{sub 2}O{sub 3}-II-type o′-In{sub 2}O{sub 3} which is thermodynamically stable at 8.5 GPa/850 °C and, thereafter, exploiting the preferred kinetics in the subsequent transformation to the rh-In{sub 2}O{sub 3} during decompression. This synthesis strategy of rh-In{sub 2}O{sub 3} was confirmed ex situ in a toroid-type high-pressure apparatus at 8 GPa and 1100 °C. The pressure–temperature phase diagrams have been constructed and the stability fields of In{sub 2}O{sub 3} polymorphs and the crystallographic relationship between them have been discussed. - Graphical abstract: In situ energy-dispersive XRD patterns in multi-anvil assemblies show the sequence of phase transition c-In{sub 2}O{sub 3}→o′-In{sub 2}O{sub 3}→rh-In{sub 2}O{sub 3} under particular pressure and temperature conditions. The tick marks refer to the calculated Bragg positions of bixbyite-type (c-In{sub 2}O{sub 3}), Rh{sub 2}O{sub 3}-II-type (o–-In2O{sub 3}) and corundum-type (rh-In{sub 2}O{sub 3}). - Highlights: • The solid-state synthesis methods can be employed for obtaining metastable phases. • The phase transition of In{sub 2}O{sub 3} was guided by DFT calculations. • The phase transition of In{sub 2}O{sub 3} was followed in situ under HP–HT conditions. • Orthorhombic o′-In{sub 2}O{sub 3} polymorph was synthesized from c-In{sub 2}O{sub 3} at 8.5 GPa/850 °C. • Metastable rh-In{sub 2}O{sub 3} was obtained from o′-In{sub 2}O{sub 3} at 5.5 GPa during decompression.

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DOE OSTI2015

Synthesis and utilization of a novel carbon nanotubes supported nanocables for the adsorption of dyes from aqueous solutions

Using multiwalled carbon nanotubes(MWCNTs) as mechanical support and glucose as carbon resource, a hydrothermal carbonization route was designed for the synthesis of MWCNTs@carbon nanocables with tunable diameter and length. MWCNTs are firstly used as templates for the formation of carbon-rich composite nanocables, and the diameter of the nanocables could be tailored through adjusting the hydrothermal time or the ratio of MWCNTs and glucose. Owing to abundant superficial oxygen-containing functional groups, porous surface and remarkable reactivity, the as-synthesized nanocables are capable of efficiently adsorbing cationic dye methylene blue (MB) and crystal violet (CV). Furthermore, the optimum adsorption conditions, kinetics, adsorption isotherms and adsorption thermodynamics of dyes were studied systematically. Additionally, the maximum adsorption capacities calculated from data analysis (298.5 mg/g for MB and 228.3 mg/g for CV) are significant higher than those of raw MWCNTs and some other adsorbents reported previously, which provides strong evidence for using MWCNTs@carbon nanocables as adsorbent to remove dyes from aqueous solutions. - Graphical abstract: MWCNTs@carbon nanocables has been successfully fabricated by a hydrothermal carbonization method. The as-synthesized novel samples were used as adsorbents and exhibited high adsorption capacity on MB and CV. - Highlights: • A simple, cost-effective and “green” method for the synthesis of the material. • The diameter and length of the material are relatively easy to control. • The surface has large oxygen-containing groups and preferable chemical reactivity. • Compared with raw MWCNTs and some other adsorbents, the adsorption capacity is much high.

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DOE OSTI2016

Hydrothermal synthesis of single crystals of transition metal vanadates in the glaserite phase

A series of transition metal vanadate crystals were prepared using a high temperature (580 °C) hydrothermal method. The compounds all had the general formula A{sub 2}AEM(VO{sub 4}){sub 2} (A=K, Na, Li; AE=Ba, Sr; M=Co, Fe, Mn). They are all variations of the glaserite structural type and range in symmetry from P-3m1 to P-3 to P2{sub 1}/c. Most of the derivatives contain a planar three-fold rotation operation, making them possible spin frustration candidates. Single crystal structural analyses were performed on many of the derivatives to obtain a detailed understanding of the distortions of the tetrahedral building blocks that accommodate the symmetry distortions. A hydrothermal growth method was developed to grow high quality single crystals of sizes up to 2–3 mm/edge. This method can be generalized for large crystal growth to enable magnetic and neutron diffraction studies that require relatively large single crystals. - Highlights: • The hydrothermal synthesis of glaserite-type vanadates is demonstrated. • Synthesis from stoichiometric component reactions yields 0.2–0.5 mm size crystals. • Hydrothermal recrystallization of glaserite powder yields 2–3 mm size crystals. • The structure varies according to the alkali and alkaline earth metals selected. • Ideal (P-3m1) and distorted (P-3 and P2{sub 1}/c) glaserite structures are observed.

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DOE OSTI2016

A review on the synthesis, crystal growth, structure and physical properties of rare earth based quaternary intermetallic compounds

This review highlights the synthesis and crystal growth of quaternary intermetallic compounds based on rare earth metals. In the first part of this review, we highlight briefly about intermetallics and their versatile properties in comparison to the constituent elements. In the next part, we have discussed about various synthesis techniques with more focus on the metal flux technique towards the well shaped crystal growth of novel compounds. In the subsequent parts, several disordered quaternary compounds have been reviewed and then outlined most known ordered quaternary compounds with their complex structure. A special attention has been given to the ordered compounds with structural description and relation to the parent binary and ternary compounds. The importance of electronic and structural feature is highlighted as the key roles in designing these materials for emerging applications. - Graphical abstract: Rare earth based quaternary intermetallic compounds crystallize in complex novel crystal structures. The diversity in the crystal structure may induce unique properties and can be considered them as future materials. - Highlights: • Crystal growth and crystal structure of quaternary rare earth based intermetallics. • Structural complexity of quaternary compounds in comparison to the parent compounds. • Novel quaternary compounds display unique crystal structure.

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DOE OSTI2016

Mechanochemical synthesis and intercalation of Ca(II)Fe(III)-layered double hydroxides

A mechanochemical method (grinding the components without added water – dry grinding, followed by further grinding in the presence of minute amount of water or NaOH solution – wet grinding) was used in this work for the preparation and intercalation of CaFe-layered double hydroxides (LDHs). Both the pristine LDHs and the amino acid anion (cystinate and tyrosinate) intercalated varieties were prepared by the two-step grinding procedure in a mixer mill. By systematically changing the conditions of the preparation method, a set of parameters could be determined, which led to the formation of close to phase-pure LDH. The optimisation procedure was also applied for the intercalation processes of the amino acid anions. The resulting materials were structurally characterised by a range of methods (X-ray diffractometry, scanning electron microscopy, energy dispersive analysis, thermogravimetry, X-ray absorption and infra-red spectroscopies). It was proven that this simple mechanochemical procedure was able to produce complex organic–inorganic nanocomposites: LDHs intercalated with amino acid anions. - Graphical abstract: Amino acid anion-Ca(II)Fe(III)-LDHs were successfully prepared by a two-step milling procedure. - Highlights: • Synthesis of pristine and amino acid intercalated CaFe-LDHs by two-step milling. • Identifying the optimum synthesis and intercalation parameters. • Characterisation of the samples with a range of instrumental methods.

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DOE OSTI2016

Novel bipyridinyl oxadiazole-based metal coordination complexes: High efficient and green synthesis of 3,4-dihydropyrimidin-2(1H)-ones through the Biginelli reactions

Three new metal coordination complexes, namely, [Co(BPO){sub 2}(H{sub 2}O){sub 4}](BS){sub 2}(H{sub 2}O){sub 2} (1), [Co(BPO){sub 2}(H{sub 2}O){sub 4}](ABS){sub 2}(H{sub 2}O){sub 2} (2), [Co(BPO){sub 2}(H{sub 2}O){sub 4}](MBS){sub 2}(H{sub 2}O){sub 2} (3) [BPO=2,5-di(pyridin-4-yl)-1,3,4-oxadiazole, BS=benzenesulphonate, ABS=4-aminobenzenesulphonate, MBS=4-methylbenzenesulphonate] were obtained under hydrothermal conditions. Complexes 1–3 were structurally characterized by single-crystal X-ray diffraction, powder X-ray diffraction, IR and thermogravimetric analyses (TGA). All of them display a zero-dimensional motif, in which strong intermolecular hydrogen bonding interactions (O–H···O/N) and packing interactions (C–H···π and π···π) make them achieve a three-dimensional supramolecular architecture. The primary catalytic results of these three complexes show that high efficiency for the green synthesis of a variety of 3,4-dihydropyrimidin-2(1H)-ones was observed under solvent free conditions through Biginelli reactions. The present catalytic protocols exhibit advantages such as excellent yield, easy isolation, eco-friendly conditions, and short reaction time. - Graphical abstract: Three new metal coordination complexes with bipyridinyl-oxadiazole were obtained under hydrothermal conditions, which display a zero-dimensional motif, and show high efficiency for the green synthesis of a variety of 3,4-dihydropyrimidin-2(1H)-ones under solvent free conditions through Biginelli reactions. The present catalytic protocols exhibit advantages such as excellent yield, easy isolation, eco-friendly conditions, and short reaction time. Display Omitted.

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DOE OSTI2016

Synthesis, characterization and electrocatalytic properties of delafossite CuGaO{sub 2}

Delafossite CuGaO{sub 2} has been employed as photocatalysts for solar cells, but their electrocatalytic properties have not been extensively studied, especially no comparison among samples made by different synthesis routes. Herein, we first reported the successful synthesis of delafossite CuGaO{sub 2} particles with three different morphologies, i.e. nanocrystalline hexagons, sub-micron sized plates and micron–sized particles by a modified hydrothermal method at 190 °C for 60 h [1–3], a sono-chemical method followed by firing at 850 °C for 48 h, and a solid state route at 1150 °C, respectively. Morphology, composition and phase purity of the synthesized samples was confirmed by powder X-ray diffraction and Raman spectroscopic studies, and then their electrocatalytic performance as active and cost effective electrode materials to the oxygen and hydrogen evolution reactions in 0.5 M KOH electrolyte versus Ag/AgCl was investigated and compared under the same conditions for the first time. The nanocrystalline CuGaO{sub 2} hexagons show enhanced electrocatalytic activity than the counterpart sub-micron sized plates and micron-sized particles. - Graphical abstract: Representative delafossite CuGaO2 samples with sub-micron sized plate and nanocrystalline hexagon morphologies accompanying with chronoamperometric voltammograms for oxygen evolution reaction and hydrogen evolution reaction in 0.5 M KOH electrolyte after purged with N{sub 2} gas. - Highlights: • Delafossite CuGaO{sub 2} with three morphologies has been synthesized. • Phase purity of the synthesized samples was confirmed. • Comparison on their electrocatalytic properties was made for the first time. • Their use as electrodes for oxygen and hydrogen evolution reactions was evaluated. • Nanocrystalline CuGaO{sub 2} hexagons show highest electrocatalytic activity.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2016

Synthesis and structure determination of the novel aluminophosphate TL-1: A new layered compound with corner-sharing AlX{sub 6} chains

A novel layered aluminophosphate (TL-1) has been synthesized. Crystals grow as pseudo-hexagonal thin platelets and their whole morphology depends on the synthesis conditions. The structure was solved by single-crystal X-ray diffraction using charge flipping methods. The synthesized layered material, with composition [AlPO{sub 4}F(H{sub 2}O)]-(H{sub 10}C{sub 4}ON){sub 4}, crystallizes in the monoclinic space group P2{sub 1}/a with a=9.2282(5) Å, b=6.9152(4) Å, c=14.4615(9) Å, β=101.57(1)°. The novel compound has corner sharing AlO{sub 3}F{sub 2}(H{sub 2}O) octahedral chains running along [010], where fluorine atoms are at the shared apices, three oxygen atoms are shared with PO{sub 4} tetrahedra while the sixth oxygen pertain to an H{sub 2}O molecule. The stability field of the novel material is enclosed in the HF/Al{sub 2}O{sub 3} ratio ranging between 1 and 4 and the HF/morpholine ratio lower than 3. At temperature lower than 190 °C, the synthesis results is a pure aluminophosphate sample (low alumina/morpholine ratio). A treatment with H{sub 2}CO{sub 3} leads to a complete morpholine removal, as shown by in situ Raman spectroscopy. Powder X-ray diffraction reveals that, after morpholine extraction, the material collapses. The collapse is irreversible. - Highlights: • A new layered aluminophosphate was obtained and characterized. • The crystal structure is a sequence of aluminophosphate and organic layers. • The stability field of the new phase was defined by changing chemistry and T. • The templating agent can be removed by using a CO{sub 2} aqueous solution. • The decomposition of the morpholine induce a collapse in the structure.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗