Search results for "Transition metals"

Determination of impurity distributions in ingots of solar grade silicon by neutron activation analysis

2017

AbstractIn a series of crystallization experiments, the directional solidification of silicon was investigated as a low cost path for the production of silicon wafers for solar cells. Instrumental neutron activation analysis was employed to measure the influence of different crystallization parameters on the distribution of 3d-metal impurities of the produced ingots. A theoretical model describing the involved diffusion and segregation processes during the solidification and cooling of the ingots could be verified by the experimental results. By successive etching of the samples after the irradiation, it could be shown that a layer of at least 60 μm of the samples has to be removed to get r…

Interactions of a Diplumbyne with Dinuclear Transition Metal Carbonyls to Afford Metalloplumbylenes

2020

The metathesis reactions of the diplumbyne AriPr6PbPbAriPr6 (AriPr6 = −C6H3–2,6-(C6H2–2,4,6-iPr3)2) with the dinuclear metal carbonyls Mn2(CO)10, Fe2(CO)9, and Co2(CO)8 under mild conditions afforded the complexes Mn(CO)5(PbAriPr6) (1), Fe(CO)4(PbAriPr6)2 (2), and Co4(CO)9(PbAriPr6)2 (3), respectively. Complexes 1–3 were structurally characterized by single-crystal X-ray diffraction and spectroscopically characterized by 1H, 13C{1H}, 59Co{1H}, and 207Pb{1H} NMR; UV–vis; and IR methods. They are rare examples of species formed by the direct reaction of a group 14 dimetallyne with transition metal carbonyls. Complexes 1 and 2 feature Mn–Pb or Fe–Pb single bonds, whereas in 3 a Co–Pb cluster i…

Input of P, N-(phosphanyl, amino)-ferrocene hybrid derivatives in late transition metals catalysis

2018

International audience; Unequally functionalized ferrocenes give access to valuable hemilabile reactivity in catalytic reaction. We address the synthesis of hybrid (P, N)-ferrocenyl compounds for which recent catalytic breakthrough applications have been reported, transversely in late transition metals chemistry. Palladium, nickel, rhodium, iridium, and emerging iron and gold catalysis are illustrated from selected examples, which include CC bond formation from cross-coupling and polymerization, allylic substitution, cyanation, hydroformylation, CH arylation and silylation and hydrogenation reactions.

Microscopic evidence of a flat melting curve of tantalum

2010

International audience; New data on the high-pressure melting curve of Ta up to 48GPa are reported. Evidence of melting from changes in sample texture was found in five different experiments using scanning electron microscopy. The obtained melting temperatures are in excellent agreement with earlier measurements using x-ray diffraction or the laser-speckled method but are in contrast with several theoretical calculations. The results are also compared with shock-wave data. These findings are of geophysical relevance because they confirm the validity of earlier experimental techniques that resulted in low melting slopes of the transition metals measured in the diamond-anvil cell, including i…

Peculiarities of Phase Formation in Mn-Based Na SuperIonic Conductor (NaSICon) Systems: The Case of Na1+2xMnxTi2–x(PO4)3 (0.0 ≤ x ≤ 1.5)

2021

This project has received funding from the European Regional Development Fund (Project no. 01.2.2-LMT-K-718-02–0005) under grant agreement with the Research Council of Lithuania (LMTLT). We thank the High Performance Computing Center “HPC Saulėtekis” at the Faculty of Physics, Vilnius University, for the use of computational resources.

Comparative Experimental and Theoretical Study of the C and O K-Edge X-ray Absorption Spectroscopy in Three Highly Popular, Low Spin Organoiron Compl…

2019

The unoccupied electronic structures of three closed-shell, highly popular organoiron complexes ([Fe(CO)5], [(η5-C5H5)Fe(CO)(μ-CO)]2, and [(η5-C5H5)2Fe]; 0, I, and II, respectively) have been investigated both experimentally and theoretically by combining original gas-phase X-ray absorption spectroscopy (XAS) outcomes recorded at the C and O K-edge with results of scalar relativistic time-dependent density functional calculations carried out within the zeroth order regular approximation. Experimental evidence herein discussed complement the Fe L2,3-edges XAS ones we recently recorded, modeled, and assigned for the same complexes (Carlotto et al. Inorg. Chem. 2019, 58, 5844). The first-princ…

Magnetic Properties of a New Hexahalorhenate(IV) Compound and Structural Comparison with Its Hexahaloplatinate(IV) Analog

2020

Decomposition studies of group 6 hexacarbonyl complexes. Part 1: Production and decomposition of Mo(CO)6 and W(CO)6

2015

Abstract Chemical studies of superheavy elements require fast and efficient techniques, due to short half-lives and low production rates of the investigated nuclides. Here, we advocate for using a tubular flow reactor for assessing the thermal stability of the Sg carbonyl complex – Sg(CO)6. The experimental setup was tested with Mo and W carbonyl complexes, as their properties are established and supported by theoretical predictions. The suggested approach proved to be effective in discriminating between the thermal stabilities of Mo(CO)6 and W(CO)6. Therefore, an experimental verification of the predicted Sg–CO bond dissociation energy seems to be feasible by applying this technique. By in…

Anion template effect and the polymerization degree

2005

Two 2D (M1 and M2) and one 1D (M3) metal‐organic frameworks (MOFs) have been prepared from pyridine functionalized tetradentate ligand tetrakis(nicotinoxymethyl)methane TNM with silver tetrafluoroborate, nickel chloride, and copper hexafluorophosphate. M1 manifests a previously unpresented mode of 4,4 threefold parallel interpenetration for 2D MOFs. Large channels (vdW diameter 9.4 Å) through eclipsed 2D layers of M2 were observed. While the open space percentage in the noninterpenetrated M2 was 38.0 %, the triple interpenetration of the sheets of M1 reduced the void to 10.8 %. With the same ligand and a similar, weakly coordinating anion as that in M1, the structure M3 was rendered one‐dim…

Band Gap Engineering and Trap Depths of Intrinsic Point Defects in RAlO3 (R = Y, La, Gd, Yb, Lu) Perovskites

2021

The work was supported by the Polish National Science Centre (Project No. 2018/31/B/ST8/00774), by the NATO SPS Project G5647, and by the Ministry of Education and Science of Ukraine (Project DB/Kinetyka no. 0119U002249). L.V. acknowledges support of the National Research Foundation of Ukraine under Grant No. 2020.02/0373 “Crystalline phosphors’ engineering for biomedical applications, energy saving lighting and contactless thermometry”. Researchers from Tartu were supported by the ERDF fundings in Estonia granted to the Centre of Excellence TK141 “Advanced materials and high-technology devices for sustainable energetics, sensorics and nanoelectronics (HiTechDevices)” (Grant No. 2014-2020.4…