| 1. |
- Alammar, Tarek, et al.
(författare)
-
Synthesis and exploration of Barium Stannate-Zirconate BaSn1-xZrxO3 (0 ≤ X ≤ 1) solid solutions as photocatalysts
- 2024
-
Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 63:14, s. 6132-6140
-
Tidskriftsartikel (refereegranskat)abstract
- Employing ionic liquid-assisted microwave synthesis and moderate heat treatment allows for the preparation of otherwise difficult-to-obtain perovskite-type BaSn1-xZrxO3 solid solutions (0 ≤ x ≤ 1). The impact of substituting Sn for the crystal structure, crystallinity, morphology, and photocatalytic performance was investigated. The obtained materials are characterized by X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller (BET) surface area analysis, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, and Raman and IR spectroscopy. SEM images show that the morphology of the samples varies from rods for x = 0, 0.2 to spherical for x = 0.5, 0.8, 1. Upon Zr for Sn substitution, the band gap changes from 3.1 to 5.0 eV as the valence and conduction bands move to lower and higher energies. The photocatalytic activities of the BaSn1-xZrxO3 samples in the hydroxylation of terephthalic acid (TA) follow the order BaSn0.5Zr0.5O3> BaSn0.8Zr0.2O3> BaSnO3> BaSn0.2Zr0.8O3> BaZrO3. The superior photocatalytic activity of BaSn0.5Zr0.5O3 can be attributed to the synergistically favorable combination of a suitable band structure, band gap size, and increased surface area-to-volume ratio, resulting in a diminished crystalline particle size unattainable from samples prepared via traditional synthetic routes or without ionic liquid.
|
|
| 2. |
- Hammond, Oliver S., et al.
(författare)
-
Small-Angle Neutron Scattering Insights into 2-Ethylhexyl Laurate : A Remarkable Bioester
- 2024
-
Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 12:5, s. 1816-1821
-
Tidskriftsartikel (refereegranskat)abstract
- Commercial (protiated) samples of the "green" and biodegradable bioester 2-ethylhexyl laurate (2-EHL) were mixed with D-2-EHL synthesized by hydrothermal deuteration, with the mixtures demonstrating bulk structuring in small-angle neutron scattering measurements. Analysis in a polymer scattering framework yielded a radius of gyration (R (g)) of 6.5 angstrom and a Kuhn length (alternatively described as the persistence length or average segment length) of 11.2 angstrom. Samples of 2-EHL dispersed in acetonitrile formed self-assembled structures exceeding the molecular dimensions of the 2-EHL, with a mean aggregation number (N-agg) of 3.5 +/- 0.2 molecules across the tested concentrations. We therefore present structural evidence that this ester can function as a nonionic (co)-surfactant. The available surfactant-like conformations appear to enable performance beyond the low calculated hydrophilic-lipophilic balance value of 2.9. Overall, our data offer an explanation for 2-EHL's interfacial adsorption properties via self-assembly, resulting in strong emolliency and lubricity for this sustainable ester-based bio-oil.
|
|
| 3. |
- Hiti, Ethan A., et al.
(författare)
-
Exploring the Role of Neutral 4-Amino-1,2,4-triazole in the Formation of Hexanuclear f-Element Hydrolysis Products
- 2024
-
Ingår i: Crystal Growth & Design. - 1528-7483 .- 1528-7505. ; 24:2, s. 834-842
-
Tidskriftsartikel (refereegranskat)abstract
- Our recent observations of an unexpected Ce(III) hydrolysis product from the reaction of 4-amino-1,2,4-triazole (4-NH2-1,2,4-Triaz) with CeCl3·7H2O, [Ce6(μ3-O)4(μ3-OH)2(μ3-Cl)2(Cl)6(μ2-4-NH2-1,2,4-Triaz)12]·7H2O, the first high-nuclearity lanthanide complex where all Ln atoms are connected pairwise through 12 N-donor ligands or 12 neutral bridging ligands of any type, prompted us to explore the utility of this ligand in trapping additional f-element examples. Reactions of LnCl3·6H2O (Ln = Nd, Eu, Ho) with a large excess of 4-NH2-1,2,4-Triaz (20 equiv) and with the addition of small amounts of water to help solubilize the metal salts led to the isolation of the unique hydrolysis products [Nd6(μ3-OH)8Cl6(μ2-4-NH2-1,2,4-Triaz)12][Cl4]·2H2O, [Eu6(μ6-Cl)0.23(μ3-O0.77)4(μ3-O)2.6(μ3-Cl)0.4Cl6(μ2-4-NH2-1,2,4-Triaz)12], and [Ho6(μ6-Cl)0.21(μ3-O0.79)4(μ3-OH)2Cl6(μ2-4-NH2-1,2,4-Triaz)12][Cl]3.4. We also report a Ce(III) analogue prepared in glassware contaminated with Pb(OAc)2, namely, [Ce6(μ3-OH)8(BrPbBr5)(μ2-4-NH2-1,2,4-Triaz)11.5(OH2)6][Pb0.84Br4.2][Br]3.8·2(4-NH2-1,2,4-Triaz)·3.6H2O. The Nd(III) complex is the structurally most ordered with a clear [Nd6(μ3-OH)8] cluster core, while the Eu(III) and Ho(III) compounds contain partial occupancy of a μ6 position and thus result in an incomplete Ln6O9 cluster core formation. The crystallographic results suggest that the 4-NH2-1,2,4-Triaz ligand brings Ln(III) ions together, followed by the formation of an Ln6O8 or Ln6O9 core with whatever remaining anions or ligands can be incorporated. Given the complexity of the hydrolysis products of nuclear waste, we expect to continue to find a myriad of closely related complex structures of these types for the f-elements.
|
|
| 4. |
- Li, Sichao, et al.
(författare)
-
Anion Architecture Controls Structure and Electroresponsivity of Anhalogenous Ionic Liquids in a Sustainable Fluid
- 2024
-
Ingår i: Journal of Physical Chemistry B. - : American Chemical Society. - 1520-6106 .- 1520-5207. ; 128:17, s. 4231-4242
-
Tidskriftsartikel (refereegranskat)abstract
- Three nonhalogenated ionic liquids (ILs) dissolved in 2-ethylhexyl laurate (2-EHL), a biodegradable oil, are investigated in terms of their bulk and electro-interfacial nanoscale structures using small-angle neutron scattering (SANS) and neutron reflectivity (NR). The ILs share the same trihexyl(tetradecyl)phosphonium ([P6,6,6,14]+) cation paired with different anions, bis(mandelato)borate ([BMB]−), bis(oxalato)borate ([BOB]−), and bis(salicylato)borate ([BScB]−). SANS shows a high aspect ratio tubular self-assembly structure characterized by an IL core of alternating cations and anions with a 2-EHL-rich shell or corona in the bulk, the geometry of which depends upon the anion structure and concentration. NR also reveals a solvent-rich interfacial corona layer. Their electro-responsive behavior, pertaining to the structuring and composition of the interfacial layers, is also influenced by the anion identity. [P6,6,6,14][BOB] exhibits distinct electroresponsiveness to applied potentials, suggesting an ion exchange behavior from cation-dominated to anion-rich. Conversely, [P6,6,6,14][BMB] and [P6,6,6,14][BScB] demonstrate minimal electroresponses across all studied potentials, related to their different dissociative and diffusive behavior. A mixed system is dominated by the least soluble IL but exhibits an increase in disorder. This work reveals the subtlety of anion architecture in tuning bulk and electro-interfacial properties, offering valuable molecular insights for deploying nonhalogenated ILs as additives in biodegradable lubricants and supercapacitors.
|
|
| 5. |
- Provino, Alessia, et al.
(författare)
-
Unusual superconductivity in crystallographically disordered RT2−xSn2 compounds
- 2024
-
Ingår i: Journal of Alloys and Compounds. - : Elsevier. - 0925-8388 .- 1873-4669. ; 1000
-
Tidskriftsartikel (refereegranskat)abstract
- The discovery of new superconducting materials represents a complementary and crucial tile to shed light on the mechanism controlling the phenomenon of superconductivity. During the search for new superconducting materials, we discovered a new series of intermetallic compounds with the general composition RZn2−xSn2 (R = La, Ce, Pr, Nd). Their formation and crystal structure have been investigated. The Zn content decreases along the series from ≈ 1.50 in LaZn1.50(1)Sn1.98(2) to ≈ 1.32 in NdZn1.321(8)Sn2.01(2), due to the partial occupation of one of the two Zn sites [the Zn1 (2c) site, which from ≈ 50% in the La compound drops to ≈ 42%, ≈ 37% and ≈ 32% in the Ce, Pr and Nd compounds, respectively]. Both the Zn occupation factor and unit cell volume follow the lanthanide contraction. No such compound has been observed with Sm. AC and DC magnetic susceptibility and transport measurements revealed LaZn1.5Sn2 to undergo a sharp superconducting transition at Tc = 5.5 K. In order to search for further possible superconductive homologues, the lanthanum substituted phases La(Zn,T)2–xSn2 (T = Ti, Mn, Fe, Co, Ni, Cu, Pd, Ag, Pt, Au, Cd; x ≈ 0.5) were also prepared. The crystal structure of the ternary compounds is a disordered defective derivative of the tetragonal CaBe2Ge2-type (tP10, P4/nmm), with a partially occupied Zn Wyckoff site and a disordered Sn position. Three related isostructural series, corresponding to three new prototypes, have been identified; they all contain conventional checkered pyramidal layers characteristic of the archetype. The magnetic and transport properties have been measured for some of these substituted quaternary La compounds and we found that superconductivity is preserved in them but in the orthorhombic compounds or when T was a magnetic transition metal (e.g., Ni or Mn). A slight decrease in Tc down to about 4.0 K was detected as a result of the Zn by T atomic substitution.
|
|
| 6. |
- Shi, Rui, et al.
(författare)
-
Manipulation of luminescence via surface site occupation in Ln3+-doped nanocrystals
- 2024
-
Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 146:17, s. 11924-11931
-
Tidskriftsartikel (refereegranskat)abstract
- Ln3+-doped (Ln = lanthanide) nanocrystals are garnering strong interest for their potential as optical materials in various applications. For that reason, a thorough understanding of photophysical processes and ways to tune them in these materials is of great importance. This study, using Eu3+-doped Sr2YF7 as a well-suited model system, underscores the (not unexpected) significance of surface site occupation of Ln3+ and also challenges the prevailing views about their contribution to the luminescence of the system. High-temperature cation exchange and epitaxial shell growth allow nanocrystals to exclusively feature Eu3+ residing at the surface or in the interior, thereby separating their spectral responses. Meticulous experiments reveal that nanocrystals with high doping concentrations exhibit luminescence primarily from surface Eu3+, in contrast to the popular belief that luminescence from surface Ln3+ is largely negligible. The present study shows, on the one hand, the necessity to revise common ideas and also reveals the potential for manipulating the luminescence of such materials through an, until now, unperceived way of surface engineering.
|
|
| 7. |
- Shtender, Vitalii, et al.
(författare)
-
Intermetallics of 4:4:1 and 3:3:1 series in La-(Co,Ni)-M (M = Bi, Pb, Te, Sb, Sn and Ga, Al) systems and their properties
- 2024
-
Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388 .- 1873-4669. ; 982
-
Tidskriftsartikel (refereegranskat)abstract
- Two series of isostructural intermetallics have been discovered in our search for new compounds with fused honeycomb motifs, both stable at elevated temperatures (1073 K). They crystallize with orthorhombic unit cells - La4Co4M (M = Sn, Sb, Te, Pb, Bi, SG Pbam, a = 8.247-8.315(2), b = 21.913-22.137(7), c = 4.750-4.664(2) angstrom, V = 850.5-869.5(4) angstrom 3, Z = 4) and La3Ni3M (M = Al, Ga, SG Cmcm, a = 4.1790-4.2395(1), b = 10.4921-10.6426 (6), c = 13.6399-13.7616(8) angstrom, V = 606.72-612.05(7), Z = 3). The crystal structures represent interesting variations of semiregular tilings of corrugated anionic layers and predominantly cationic zigzag motifs. The La4Co4M compounds reveal a complex type of ordering with a high degree of frustration as could be expected for the Kagome ' -related lattices, while magnetic ordering in the La3Ni3M series is less evident. Electronic structure calculations have been performed for multiple compounds within both series revealing metallic character and visible local minima around the Fermi level. The bonding picture is characterized by nearly equal contributions from the anionic and the cationic components.
|
|
| 8. |
- Siebeneichler, Stefanie, et al.
(författare)
-
Making a Hedgehog Spin-Vortex State Possible : Geometric Frustration on a Square Lattice
- 2024
-
Ingår i: Chemistry of Materials. - 0897-4756 .- 1520-5002. ; 36:8, s. 3546-3554
-
Tidskriftsartikel (refereegranskat)abstract
- Magnetic materials with noncollinear spin arrangements are of considerable interest owing to their potential use in emerging computational technologies and memory devices. Competing magnetic interactions, i.e., magnetic frustration, are one of the main origins of noncollinear magnetic structures. While frustrated systems have been mainly studied among magnetic insulators, combining magnetic frustration with electrical conductivity can allow simultaneous charge and spin manipulation, which is crucial for the design of electronic devices. Here, we present a new intermetallic solid solution LaMn2–xAu4+x, whose crystal structure accommodates magnetically frustrated Mn square nets. Powder neutron diffraction and first-principles analysis provide evidence that the metallic LaMn2–xAu4+x phase can host the frustration-driven hedgehog spin-vortex crystal─a rare noncollinear magnetic state, which was previously exclusively observed for iron pnictides.
|
|
