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At least 1,657 records · Page 92
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Hydrothermal synthesis and structural analysis of new mixed oxyanion borates: Ba{sub 11}B{sub 26}O{sub 44}(PO{sub 4}){sub 2}(OH){sub 6}, Li{sub 9}BaB{sub 15}O{sub 27}(CO{sub 3}) and Ba{sub 3}Si{sub 2}B{sub 6}O{sub 16}

Several new borate compounds, Ba{sub 11}B{sub 26}O{sub 44}(PO{sub 4}){sub 2}(OH){sub 6} (1), Li{sub 9}BaB{sub 15}O{sub 27}(CO{sub 3}) (2), and Ba{sub 3}Si{sub 2}B{sub 6}O{sub 16} (3) were synthesized containing other hetero-oxyanion building blocks in addition to the borate frameworks. They were all prepared under hydrothermal conditions and characterized by single crystal and powder X-ray diffraction, and IR spectroscopy. Crystal data: For 1; space group P2{sub 1}/c, a=6.8909 (14) Å, b=13.629 (3) Å, c=25.851 (5) Å, β=90.04 (3)°; For 2; space group P-31c, a=8.8599 (13) Å, c=15.148 (3) Å; For 3; space group P-1, a=5.0414 (10) Å, b=7.5602 (15) Å, c=8.5374 (17) Å, α=77.15 (3)°, β=77.84 (3)°, γ=87.41 (3)° for 3. Compounds 1 and 2 contain isolated oxyanions [PO{sub 4}]{sup 3−} and [CO{sub 3}]{sup 2−} respectively, sitting in channels created by the borate framework, while structure 3 has the [SiO{sub 4}]{sup 4−} groups directly bonded to the borate groups creating a B–O–Si framework. - Highlights: • Hydrothermal syntheses of three new mixed oxyanion borates are presented. • Ba{sub 11}B{sub 26}O{sub 44}(PO{sub 4}){sub 2}(OH){sub 6} contains isolated [PO{sub 4}]{sup 3−} in voids of the borate framework. • Li{sub 9}BaB{sub 15}O{sub 27}(CO{sub 3}) contains isolated [CO{sub 3}]{sup 2−} in channels created by the framework. • Ba{sub 3}Si{sub 2}B{sub 6}O{sub 16} has direct bonding of [SiO{sub 4}]{sup 4−} and borates creating a B–O–Si framework.

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

3D dendritic α-Fe{sub 2}O{sub 3} nano-architectures: Synthesis and its application on electrochemical non-enzymatic H{sub 2}O{sub 2} sensing

In this manuscript we have successfully synthesized a large scale 3D dendritic α-Fe{sub 2}O{sub 3} hierarchical structure via a hydrothermal reaction. The crystallinity, composition, purity, morphology of the synthesized α-Fe{sub 2}O{sub 3} are characterized by powder X-ray diffraction (PXRD), field emission scanning electron microscopic (FESEM), energy dispersive X-ray spectroscopic (EDS). FESEM image reveals that the individual α-Fe{sub 2}O{sub 3} dendrite consists of a long central trunk with secondary and tertiary branches. For electrochemical H{sub 2}O{sub 2} sensing we have carried out cyclic voltammetry (CV), amperometric i-t measurement. It has been found that the current density vs. H{sub 2}O{sub 2} concentration calibration curve is linear in nature. The present study reveals that the dendritic α-Fe{sub 2}O{sub 3} hierarchical structure exhibits very sensitive electrochemical sensing capability towards H{sub 2}O{sub 2} reduction.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Synthesis, structure, and stability of a novel 2 H -azirine under pressure

We have synthesized 2,3-diphenyl-2H-azirine, a strained unsaturated heterocyclic compound, and examined its high-pressure behavior to above 10 GPa using diamond anvil cell techniques. Single crystal X-ray diffraction at ambient conditions reveals that the crystal structure is hexagonal and consists of interesting helices surrounding voids in the structure. A continuous shift of the Raman and infrared vibrational spectra with increasing pressure is observed, indicating that the molecular structure is preserved to at least 8 GPa at room temperature. High-pressure synchrotron powder X-ray diffraction shows that the hexagonal structure persists, with a smooth compression of the a and c parameters to 10 GPa. The structural stability under pressure is attributed to the reduction in void size within the helical framework despite the inherent strain and reactivity of the molecule. The channels in the structure could encapsulate small molecules for gas or energy storage applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Antiferromagnetic ordering in NdAuGe compound

The compound NdAuGe was investigated by means of electrical resistivity, ρ(T), magnetic susceptibility, χ(T), magnetization, σ(μ{sub 0}H), and specific heat, C{sub p}(T), measurements. Powder X-ray diffraction studies confirm a hexagonal LiGaGe-type structure with space group P6{sub 3}mc (No. 186). ρ(T) data show normal metallic behaviour and a tendency toward saturation at higher temperatures. The low temperature ρ(T) data indicate a phase transition around 3.8 K. The low field dc χ(T) data show an antiferromagnetic anomaly associated with a Néel temperature at T{sub N} = 3.7 K close to the phase transition observed in ρ(T) results. At higher temperatures, χ(T) follows the paramagnetic Curie-Weiss behaviour with an effective magnetic moment μ{sub eff}=3.546(4) μ{sub B} and a paramagnetic Weiss temperature of θ{sub p}=−6.1(4) K. The value obtained for μ{sub eff} is close to the value of 3.62 μ{sub B} expected for the free Nd{sup 3+}-ion. σ(μ{sub 0}H) shows a linear behaviour with applied field up to 3 T with an evidence of metamagnetic behaviour above 3 T. C{sub p}(T) confirms the magnetic phase transition at T{sub N} = 3.4 K. The 4f-electron specific heat indicates a Schottky-type anomaly around 16.5 K with energy splitting Δ{sub 1}=25.8(4) K and Δ{sub 2}=50.7(4) K of the Nd{sup 3+} (J = 9/2) multiplet, that are associated with, respectively, the first and second excited states of the Nd{sup 3+}-ion.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2026

Synthesis and Properties of Bulk Mg 3 WN 4 in a Wurtzite-Derived Structure

Experimental synthesis of theoretically predicted materials with controlled elemental coordination environments can lead to the realization of useful properties, such as facile ion transport or ferroelectric switching. Among such materials are ternary nitrides in the Mg−W−N composition space, where several stable and metastable compounds have been predicted and synthesized recently in bulk and film forms. Here, we report for the first time on the bulk synthesis of Mg 3 WN 4 in a wurtzite-derived crystal structure via a solid-state metathesis reaction. In situ synchrotron powder X-ray diffraction shows how the ion exchange proceeds from Li 6 WN 4 + MgCl 2 precursors to Mg 3 WN 4 + LiCl products, with the reaction starting slowly near 380 °C and completing by 600 °C, including the presence of a competing disordered rocksalt-derived phase (Mg,W)N above 440 °C. The follow-up ex situ powder synthesis at 400 °C for 0.5 h with 10% excess MgCl 2 reveals the cation-ordered nature of the wurtzite-derived Mg 3 WN 4 structure with polar symmetry confirmed by second-harmonic generation measurements. Optical absorption spectra, chemical composition analysis, and electron microscopy imaging suggest that bulk Mg 3 WN 4 obtained via metathesis reaction is prone to defect formation. Overall, this study shows that selective ex situ synthesis of the phase-pure ternary nitrides, informed by in situ measurements, is possible by carefully controlling the thermal budget of the reaction and paves the way toward property characterization of the Mg 3 WN 4 wurtzite-derived material.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Structural and degradation studies of a biocompatible Zn-L-tartrate metal–organic framework

New anhydrous Zn-L-tratrate was synthesized under hydrothermal conditions. Crystal structure which was solved by powder X-ray diffraction data from monoclinic unit cell (I{sub 2}, a=11.7557(1), b=9.0319(1), c=5.0750(1), β=91.920(1)) consists of the three-dimensional framework where each Zn atom coordinates four tartrate ligands in distorted octahedral geometry. Due to its biocompatible components, the degradation of material was studied in aqueous media under different pH values (pH=1–7) and in the simulated body fluid (pH=7.4) performed by the measurement of the released Zn{sup 2+} concentrations at thermostatic conditions (37 °C). The results showed that under acidic conditions approximately 60% of Zn{sup 2+} is released from the investigated material after 6 h of degradation process. With the increase of the solution’s pH, the rate of degradation gradually decreases. XRD and SEM analyses indicate that in aqueous media the compound slowly disintegrates and does not undergo hydrolysis process regardless of pH. Biocompatibility of the compound and its controllable rate of degradation even in acid conditions open its potential use in the fields of bio-applications. - Graphical abstract: The degradation kinetics of Zn-L-tar MOF material in aqueous media at different pH conditions. - Highlights: • Anhydrous chiral Zn-L-tratrate was synthesized under hydrothermal conditions. • 3-D framework consists of Zn atoms, each chelating four tartrate ligands. • Degradation of material was studied in aqueous media at different pH values. • The compound disintegrates in controllable manner in aqueous solutions. • The rate compound degradation is increasing with increased acidity of solution.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Dense nitrogen-rich energetic materials: A study of 5,5{sup ′}-(1H-tetrazolyl)amine

5,5{sup ′}-(1H-tetrazolyl)amine (BTA), a nitrogen rich molecular solid has been investigated under compression at room temperature. Powder x-ray diffraction using synchrotron radiation and micro-Raman spectroscopy were carried out to pressures up to 12.9 GPa. BTA conserves the crystalline structure of its room condition phase up to the highest pressure, i.e., an orthorhombic unit cell (Pbca). A fit of the isothermal compression data to the Birch-Murnaghan equation of state reveals the high compressibility of BTA. An analysis of the volume change with pressure yields a bulk modulus and its derivative similar to that of high-nitrogen content molecular crystals. Upon laser heating to approximately 1100 K, the sample decomposed while pressurized at 2.1 GPa, resulting in a graphitic compound. Finally, numerical simulations demonstrate that the minimum energy conformation is not experimentally observed since a higher energy conformation allows for a more stable dense packing of the BTA molecules.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Two new helical compounds based on Keggin clusters and N-donor multidentate ligand: Syntheses, structures and properties

Two isostructural polyoxometalate-based inorganic–organic hybrids with 1D helical chain, [CuH{sub 3}L{sub 2}(GeMo{sub 12}O{sub 40})]·2H{sub 2}O (1) and [CuH{sub 3}L{sub 2}(SiMo{sub 12}O{sub 40})]·2H{sub 2}O (2), where L=2,4,5-tri(4-pyridyl)-imidazole have been synthesized under hydrothermal conditions. It is the first time to use the L ligand to synthesis the Keggin-type polyoxometalate-based inorganic–organic hybrids. The two compounds possess the left- and right-handed helical chains and the POMs as pendants attach in the helical chains through Cu–O bonds. The two compounds have been characterized by elemental analyses, infrared (IR) spectroscopy, powder X-ray diffraction (PXRD), X-ray photoelectron spectra (XPS), thermogravimetric analysis (TGA) and photoluminescent spectroscopy. Moreover, nitrogen adsorption−desorption measurement, electrochemical and photocatalysis properties for degradation of methylene blue (MB) upon a UV irradiation of compound 1 have been examined. - Graphical abstract: Two new compounds, [CuH{sub 3}L{sub 2}(GeMo{sub 12}O{sub 40})]·2H{sub 2}O (1) and [CuH{sub 3}L{sub 2}(SiMo{sub 12}O{sub 40})]·2H{sub 2}O (2) have been synthesized under hydrothermal conditions. The two compounds possess the left- and right-handed helical chains. - Highlights: • The tridentate L ligand is first used to synthesis Keggin-type polyoxometalates. • The two compounds possess the left- and right-handed Cu–L helical chains. • Relationship between surface properties and photocatalytic activity was studied. • Two compounds exhibit photoluminescence of ligand-to-metal charge transfer.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Photoluminescence properties of AlN-doped BaMgAl{sub 10}O{sub 17}:Eu{sup 2+} phosphors

Highlights: ► Ideal hexagonal shape particle size in 5 μm and 2.5–3 μm in thickness are obtained. ► The growth mechanism is studied by a computer simulation. ► The influence of introduced AlN on the sites of Eu{sup 2+} and photoluminescence properties was investigated. - Abstract: The AlN-doped BaMgAl{sub 10}O{sub 17}:Eu{sup 2+} phosphors were synthesized by conventional solid-state reaction. Powder X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence spectrum (PL) were used for characterization. The growth mechanism was carried out by computer simulation with CASTEP application, and revealed that an ideal hexagonal shape, particle size in 5 μm and 2.5–3 μm in thickness, could be obtained by AlN doping. Additionally, due to the low electronegativity of N{sup 3−}, the AlN-doped sample showed 35% increase in PL intensity and improvement of thermal stability. These fine particle size and better photoluminescence properties are expected to be applicable to industrial production of BaMgAl{sub 10}O{sub 17}:Eu{sup 2+} phosphors.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Efficient extraction of inorganic selenium from water by a Zr metal–organic framework: investigation of volumetric uptake capacity and binding motifs

Strict monitoring and control of selenium concentrations in freshwater supplies is critical to safeguarding human health and aquatic life. A handful of previously investigated sorbents exhibit noteworthy gravimetric (mg g -1 ) Se uptake capacities; however, often display insufficient volumetric (mg cm -3 ) capacities, thereby requiring large volumes of material for commercial implementation. In this paper, in pursuit of mitigating this material inefficiency, we investigated the selenite (SeO 3 2- ) and selenate (SeO 4 2- ) affinity of MOF-808, a Zr-based metal–organic framework with a high density of potential Se oxyanion binding sites. MOF-808 recorded exceptional volumetric and gravimetric Se oxyanion capacities of 133 mg g -1 (127 mg cm -3 ) and 118 mg g -1 (112 mg cm -3 ) for aqueous selenite and selenate, respectively. Single-crystal X-ray diffraction studies revealed that selenite and selenate can bind at the MOF node via two distinct binding motifs, an η 2 μ 2 motif in which the oxyanion coordinates to two different metal atoms in a single node, and a μ 2 motif in which the oxyanion interacts with only a single metal atom. Finally and furthermore, powder X-ray diffraction (PXRD) patterns and N 2 adsorption/desorption isotherms confirm the retention of bulk crystallinity and porosity after the uptake of Se oxyanions.

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

Blue emission of Eu{sup 2+} doped LaMgAl{sub 11}O{sub 19} phosphor prepared by combustion synthesis method

Blue-emitting phosphor LaMgAl{sub 11}O{sub 19}:Eu{sup 2+} has been synthesized successfully at 500 °C by one step combustion synthesis method. The as-synthesized materials were characterized by powder x-ray diffraction (XRD) and photoluminescence (PL) techniques. Upon 365 nm excitation, emission spectra of the LaMgAl{sub 11}O{sub 19}:Eu{sup 2+} phosphors show a blue band at 450 nm. The excitation spectra corresponding to 4f{sup 7}-4f{sup 6}5d transition of Eu{sup 2+} cover the spectral range of 280–430 nm. The concentration quenching of Eu{sup 2+} in the LaMgAl{sub 11}O{sub 19} host was determined to be 3 mol%. The CIE chromaticity of LAM: Eu{sup 2+} phosphors was compared with the commercial BAM.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Anion-controlled assembly of metal 3,5-bis(benzimidazol-1-ylmethyl) benzoate complexes: Synthesis, characterization and property

Hydrothermal reactions of 3,5-bis(benzimidazol-1-ylmethyl)benzoic acid (HL) with Cd(II), Cu(II) and Zn(II) salts provide eight new metal complexes which were characterized by single crystal and powder X-ray diffraction, IR, elemental and thermogravimetric analyses. Two cadmium frameworks [Cd(L){sub 2}]·2H{sub 2}O (1) and [Cd(L)Cl] (2) have 3D structures with (4{sup 2}.6{sup 5}.8{sup 3})(4{sup 2}.6) and rtl (4.6{sup 2}){sub 2}(4{sup 2}.6{sup 10}.8{sup 3}) topologies, respectively. Structural diversity of four copper complexes [Cu{sub 3}(L){sub 2}]·NO{sub 3}·0.5H{sub 2}O (3), [Cu{sub 2}(HL){sub 2}(SO{sub 4})]·3.5H{sub 2}O (4), [Cu(L)(bdc){sub 0.5}]·1.5H{sub 2}O (5) and [Cu{sub 2}(L)(HL)(Hbdc)] (6) (H{sub 2}bdc=1,4-benzenedicarboxylic acid) is achieved through the alteration of copper salts and addition of auxiliary ligand. As a result, 3 has a 1D ladder structure, 4 is a discrete dinuclear complex, 5 displays a (3,4)-connected 2-nodal 3-fold interpenetrating framework with (4{sup 2}.6.10{sup 2}.12)(4{sup 2}.6) topology, 6 exhibits a 4-connected uninodal 2D sql (4{sup 4}.6{sup 2}) network. Within the zinc series, ZnCl{sub 2} and ZnSO{sub 4} were used for the syntheses of [Zn(L)Cl] (7) and [Zn(L)(SO{sub 4}){sub 0.5}]·2H{sub 2}O (8), respectively. 7 shows a 3-connected uninodal 2D hcb network with (6{sup 3}) topology and 8 is a (3,6)-connected 2-nodal 3D framework with (4{sup 2}.6){sub 2}(4{sup 4}.6{sup 2}.8{sup 8}.10) topology. The luminescent properties of the Cd(II) and Zn(II) complexes were investigated. - Graphical abstract: Eight new complexes have been successfully synthesized from the hydrothermal reactions of Cd(II), Cu(II) and Zn(II) salts with 3,5-bis(benzimidazol-1-ylmethyl)benzoic acid. The complexes exhibited anion-controlled structural diversity. - Highlights: • Metal complexes have diverse structures of 1D chains, 2D networks and 3D frameworks. • Anion-controlled assembly of the complexes is reported. • The luminescent properties of the Cd(II) and Zn(II) complexes were investigated.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Novel mixed hydroxy-carbonate precursor assisted synthetic technique for LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2} cathode materials

Highlights: • MHC method used to overcome drawbacks of solid state synthesized materials. • Least cation mixing, phase purity, good reversibility and rate capability achieved. • XRD I {sub 0} {sub 0} {sub 3}/I{sub 1} {sub 0} {sub 4} factor, indicating electrochemical reactivity is maximum at 1.6984. • Li/LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2} cell delivered an initial discharge capacity of 175 mAh g{sup −1}. - Abstract: Novel mixed hydroxy-carbonate (MHC) precursors were used to synthesis technique of LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2} cathode material. The powder X-ray diffraction (XRD) pattern of the synthesized LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2} cathode materials exhibited a hexagonal cell with a = 2.8535 Å and c = 14.2040 Å. Fourier transform infrared spectroscopy (FT-IR) spectrum of MHC and LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2} consistent with vibration modes of functional group. Presence of sub-micrometer particle size (200 nm) and highly crystalline morphology confirmed using scanning electron microscopy (SEM). X-ray photoelectron spectroscopy (XPS) suggested that oxidation state of the transition metals; Ni in +2, Mn in +4 and Co in +3 states, respectively in LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2} cathode materials. Cyclic voltammograms (CV) revealed only one major redox couple at 4 V and suggested the absence of structural transitions from hexagonal to monoclinic structure. The Li vs. LiNi{sub 1/3}Mn{sub 1/3}Co{sub 1/3}O{sub 2} cell delivered an initial discharge capacity of 175 mAh g{sup −1} in the voltage range 2.5–4.6 V @ 0.1 C.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Structural and magnetic investigation of In{sub 2}Fe{sub 2−x}Ga{sub x}CuO{sub 7}

The solid solution of In{sub 2}Fe{sub 2−x}Ga{sub x}CuO{sub 7} (space group P6{sub 3}/mmc) was synthesized and investigated through X-ray diffraction and magnetic susceptibility studies. Limited changes to the lattice parameters were observed as a result of the similar ionic radii for Fe{sup 3+} and Ga{sup 3+} in the trigonal bipyramidal (TBP) crystallographic site. An increase in the Weiss temperature, along with spin glass behavior are observed from x=0 to x=2, but irregularities in the trend are apparent for x=0.75 and 1. With the highest concentration in magnetic ions, In{sub 2}Fe{sub 2}CuO{sub 7} appears to have competing nearest neighbor interactions that produce a suppression of the Curie tail and the experimental magnetic moment. In comparison to InFe{sub 1−x}Ga{sub x}CuO{sub 4}, both solid solutions show an invariable progression of the lattice parameters, but the magnetic properties are greatly affected by the distinct TBP layering schemes. - Graphical abstract: Solid solution of In{sub 2}Fe{sub 2−x}Ga{sub x}CuO{sub 7} has been synthesized and analyzed with powder X-ray diffraction and DC magnetic susceptibility studies. The magnetic ground state has been investigated through cation substitution and compared to that of InFe{sub 1−x}Ga{sub x}CuO{sub 4}. Highlights: • The complete solid solution of In{sub 2}Fe{sub 2−x}Ga{sub x}CuO{sub 7} has been synthesized. • Limited changes in the lattice parameters were observed through XRD refinements. • Spin glass magnetic interactions were found to depend on Fe{sup 3+} content. • The layering of the TBP greatly affects the observed magnetic interactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Low-temperature synthesis, structural and magnetic properties of self-dopant LaMnO{sub 3+δ} nanoparticles from a metal-organic polymeric precursor

Graphical abstract: Monophasic and highly crystalline Self-dopant LaMnO{sub 3+δ} nanoparticles (72 nm) have been successfully synthesized at low temperature (773 K) by metal citrate complex method based on Pechini-type reaction route which showed ferromagnetic interaction. Surface areas of LaMnO{sub 3+δ} nanoparticles were found to be 157.4 and 153 m{sup 2} g{sup −1} for the samples annealed at 773 K and 1173 K, respectively. - Highlights: • Self-dopant LaMnO{sub 3+δ} nanoparticles using Pechini-type reaction route at 773 K. • Size range varies from 72 to 80 nm. • Surface area varies from 153 to 157 m{sup 2} g{sup −1}. • Extensive characterization using sophisticated techniques. - Abstract: Self-dopant LaMnO{sub 3+δ} nanoparticles have been successfully synthesized by metal citrate complex method based on Pechini-type reaction route, at low temperature (773 K). Powder X-ray diffraction and transmission electron microscope revealed pure and nanostructured phase of LaMnO{sub 3+δ} (δ = 0.125) with an average grain size of ∼72 nm (773 K) and ∼80 nm (1173 K). DC-magnetization measurements under an applied magnetic field of H = ±60 kOe showed an increase in the magnetization with the increase of calcination temperature. Ferromagnetic nature shown by non-stoichiometric LaMnO{sub 3+δ} was verified by well-defined hysteresis loop with large remanent magnetization (M{sub r}) and coercive field (H{sub c}). Surface areas of LaMnO{sub 3+δ} nanoparticles were found to be 157.4 and 153 m{sup 2} g{sup −1} for the samples annealed at 773 K and 1173 K, respectively.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Crystal structure and dielectric properties of layered perovskite-like solid solutions Bi{sub 3–x}Y{sub x}TiNbO{sub 9} (x = 0, 0.1, 0.2, 0.3) with high Curie temperature

The structural and electrophysical characteristics of a number of solid solutions of layered perovskite-like oxides Bi{sub 3–x}Y{sub x}TiNbO{sub 9} (x = 0, 0.1, 0.2, 0.3) have been studied. According to the data of powder X-ray diffraction, all the compounds are single-phase with the structures of two-layer Aurivillius phases (m = 2) with the orthorhombic crystal lattice (space group A2{sub 1}am). The temperature dependence of the relative permittivity ε/ε0(T) compounds have been measured and showed that the Curie temperature of the perovskite-like oxides Bi{sub 3–x}YxTiNbO{sub 9} linearly increases with the substituting parameter x up to T{sub C} = 965°C.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Synthesis, structure and photoluminescence properties of Sm{sup 3+}-doped BiOBr phosphor

Well-crystallized tetragonal layered BiOBr and Bi{sub 0.95}Sm{sub 0.05}OBr phosphors were prepared by the solid state method. These compounds were characterized using powder X-Ray diffraction and photoluminescence technique. In PL spectra, the electric dipole transitions dominate than other transitions which indicate that the Sm{sup 3+} ions occupy a site with an inversion center of BiOBr. CIE chromaticity diagram confirmed that these phosphors can be useful in the fabrication of red component in white light emitting diodes (WLEDs) for display device applications.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Combustion synthesis of MgO nanoparticles using plant extract: Structural characterization and photoluminescence studies

Magnesium oxide nanoparticles (MgO Nps) have been successfully synthesized via solution combustion method using Parthenium plant extract as fuel for the first time. Powder X-ray diffraction (PXRD) pattern reveal that product belongs to the cubic phase (Periclase). FTIR spectrum shows the band at 822 cm{sup −1} indicates the formation of cubic periclase MgO. The optical band gap of MgO Nps estimated from UV –Vis spectrum was found to be in the range 5.40–5.45 eV. SEM images showed that, the product is agglomerated and particle in nature. Photoluminescence (PL) studies shows violet emission at 390 nm, blue emission at 470 nm and green emission at 550 nm. MgO Nps shows good photocatalytic activity for the degradation of methylene blue (MB) dye under UV/Sun light irradiation.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗