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Crystal structure and physical properties of new Ca2TGe3 (T = Pd and Pt) germanides
PublikacjaThe crystallographic, electronic transport and thermal properties of Ca2PdGe3 and Ca2PtGe3 are reported. The compounds crystalize in an ordered variant of the AlB2 crystal structure, in space group P6/mmm, with the lattice parameters a = 8.4876(4) Å/8.4503(5) Å and c = 4.1911(3) Å/4.2302(3) Å for Ca2PdGe3 and Ca2PtGe3, respectively. The resistivity data exhibit metallic behavior with residual-resistivity-ratios (RRR) of 13 for...
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A complete impedance analysis of electrochemical cells used as energy sources
PublikacjaA comprehensive description of impedance ofelectrochemical systems has been presented, along withthe assumptions of the method used. In this method, amultisinusoidal current excitation signal is used. Thechanges of potential of both the electrodes and thepotential difference between these electrodes are allregistered simultaneously as a function of time. Theproposed method offers the possibility of separatelydetermining the instantaneous...
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Effect of composition on the thermal properties and structure of M-Al-Si-O-N glasses, M = Na, Mg, Ca
PublikacjaThe primary objective of this study is to explore the relationship between the composition, structure, and thermal characteristics of M-Al-Si-O-N glasses, with M representing sodium (Na), magnesium (Mg), or calcium (Ca). The glasses were prepared by melting in a quartz crucible at 1650 °C and AlN precursor (powder) was utilized as a nitrogen source. The measured thermal properties studied were glass transition temperature (Tg),...
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Biosilica from sea water diatoms algae—electrochemical impedance spectroscopy study
PublikacjaHere, we report on an electrochemical impedance study of silica of organic origin as an active electrode material. The electrode material obtained from carbonized marine biomass containing nanoporous diatoms has been characterised by means of XRD, IR, SEM and EIS. Dif- ferent kinds of crystallographic phases of silica as a result of thermal treatment have been found. The electrode is electrochemically stable during subsequent cyclic...
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Does the low optical band gap of yellow Bi3YO6 guarantee the photocatalytical activity under visible light illumination?
PublikacjaBi3YO6, which is known as an ionic conductor, was tested here as an electrode and photoanode in contact with aqueous electrolytes. Bi3YO6 was deposited onto the Pt substrate and the such prepared electrode was polarized in various aqueous electrolytes. The optical energy band gap of the material equal to 1.89 eV was determined using the Kubelka-Munk function resulting from the UV-Vis spectrum (allowed indirect transition) and also...
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Composites of tin oxide and different carbonaceous materials as negative electrodes in lithium-ion batteries
PublikacjaAbstract Tin and tin oxide have been considered as suitable materials with high theoretical capacity for lithium ion batteries. Their low cost, high safety and other technical benefits placed them as promising replacements for graphite negative electrodes. The problem to overcome with tin oxide, as well as with other metallic materials, is high volume changes during alloying/dealloying, subsequent pulverization, delamination from...
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A field programmable analog array for CMOS continuous-time OTA-C filter applications
PublikacjaW artykule opisano programowalny wzmacniacz transkonduktancyjny oraz konfigurowalny blok analogowy CAB składający się ze wzmacniacza transkonduktancyjnego, kluczy oraz programowalnego kondensatora. Z bloków CAB można zbudować uniwersalne, programowalne filtry. Wzmacniacz transkondukancyjny został przesymulowany oraz wykonany w technologii CMOS. Wyniki pomiarów pokazują, że transkonduktancja wzmacniacza może być przestrajana ponad...
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Nitride LEDs and Lasers with Buried Tunnel Junctions
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Synthesis of 3-D Graphene via Combustion Synthesis of Magnesium and Calcium/Magnesium Oxalates
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Functionalized nanodiamonds as a perspective green carbo-catalyst for removal of emerging organic pollutants
PublikacjaRapid industrial and urban development jointly with rising global population strongly affect the large-scale issues with drinking, groundwater, and surface water pollution. Concerns are not limited to environmental issues but also human health impact becoming serious global aspect. Organic pollution becomes a primarily serious hazard, therefore, the novel sophisticated approaches to treat them are thoroughly investigated. Among...
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Study of the transport properties of a molecular junction as a function of the distance between the leads
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Collective excitations in the hubbard model with intrasite attraction
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Collective Excitations in the Extended Hubbard Model with Intrasite Attraction
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Nuclear Magnetic Relaxation and d-Wave Pairing in a Model of a Superconductor with Non-Retarded Attraction
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On the selectivity of nanostructured semiconductor gas sensors
Publikacja.
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Combining tight-binding and molecular dynamics methods to model the behaviour of metals in the plastic regime
PublikacjaOpisujemy zastosowanie metody dwuskalowej (kwantowo-klasycznej) w zastosowaniu do metali. Region energetycznie najważniejszy jest traktowany kwantowo, podczas gdy reszta układu jest traktowana klasycznie. Wprowadzamy własną implementację metody oraz przedstawiamy uzyskane wyniki dla metali.
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Electronic structure of CeBa2Cu3O7.
PublikacjaPrzeprowadzono obliczenia ab initio struktury elektronowej związku CeBa2Cu3-O7(Ce123) metodą LAPW oraz porównano z analogicznymi strukturami otrzymanymi dla YBa2Cu3O7 (Y123), NdBa2Cu3O7(Nd123) i PrBa2Cu3O7(Pr123). Wszystkie wyliczone struktury pasmowe są zasadniczo podobne. W pracy postawiono hipotezę dotyczącą korelacji pomiędzy silnym rozszczepieniem spinowym w Pr123 i Ce123a niestabilnością strukturalną tych układów.
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Electronic structure of TbBa2Cu3O7
PublikacjaW pracy wykonano obliczenia kwantowomechaniczne struktury elektronowej hipotetycznego materiału TbBa2Cu3O7 (Dy123) metodą FP-LAPW (full potential - linearized augmented plane wave) w ramach formalizmu DFT (density functional theory) stosując przybliżenie GGA (generalized gradient approximation). Ze względu na silne oddziaływania korelacyjne elektronów 4f w atomie Tb zastosowano dodatkowo poprawkę kulombowską U w ramach modelu...
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Electrical conductivity and relaxation processes in V2O5 nanorods prepared by sol–gel method
PublikacjaProperties of high purity V2O5 nanorods prepared by a sol – gel method are presented. The studied materials were characterized by: X-ray diffractometry (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The electrical impedance was measured as a function of temperature and frequency. The obtained results show that the electrical conductivity increases with increasing temperature. The d.c. conductivity...
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Mixed ionic-electronic conductivity and structural properties of strontium-borate glass containing nanocrystallites of Bi2 VO5.5
PublikacjaSamples of strontium borate glass containing bismuth vanadate nanocrystallites were prepared. Nanocomposites containing up to 45mol% of the Bi2VO5.5 phase exhibit electrical properties closer to the strontium-borate glass than to the ferroelectric Bi2VO5.5 ceramic. The glass matrix still may contain some part of bismuth and vanadium ions even after crystallization process and there is too little of crystalline phase to observe...
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Singlet Exciton Diffusion in Vacuum-Evaporated Films of Amine-Based Materials as Studied by Photocurrent and Photoluminescence Quenching Methods
PublikacjaThe singlet exciton diffusion lengths are determined by the photoconductivity as well as the luminescence surface quenching technique, in vacuum‐evaporated layers of (4,4′,4″‐tris(N‐(3‐methylphenyl)‐N‐phenylylamino) triphenylamine) (m‐MTDATA), 4,4′,4″‐tris[2‐naphthyl(phenyl)amino] triphenylamine (2TNATA), and N,N′‐diphenyl‐N,N′‐bis(3‐methylphenyl)‐[1,1′‐biphenyl]‐4,4′‐diamine (TPD) which are frequently used for fabrication of electroluminescent...
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Effect of the template-assisted electrodeposition parameters on the structure and magnetic properties of Co nanowire arrays
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Fabrication of the cross-linked PVA/TiO2/C nanocomposite membrane for alkaline direct methanol fuel cells
PublikacjaA crosslinked Poly(vinyl alcohol) based composite membrane was developed through a phase inversion process for use in alkaline direct methanol fuel cells (ADMFCs). The titanium dioxide (TiO2) and carbon nanoparticles (NPs) have been incorporated into the PVA polymer matrix to improve the mechanical and thermal properties. The membrane samples were further modified with maleic acid, a carboxylic acid acting as the cross-linker,...
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Power devices in Polish National Silicon Carbide Program
PublikacjaArtykuł zawiera informacje o polskim rządowym programie ''Nowe technologie na bazie węglika krzemu i ich zastosowania w elektronice wielkich częstotliwości, dużych mocy i wysokich temperatur''. Program zawiera trzy główne zadania zawierające następujące cele: wytworzenie podłoży z SiC, wytworzenie przyrządów z SiC oraz ocenę działania wybranych przyrządów w układach aplikacyjnych. Omówiono zastosowane metody wytwarzania podłoży,...
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Comparison of ZnO:Al, ITO and carbon nanotube transparent conductive layers in flexible solar cells applications
PublikacjaW artykule zostały przetestowane różne typy transparentnych elektrod z uwagi na właściwości mechaniczne, optyczne oraz elektryczne. Wszystkie przebadane materiały zostały nałożone w postaci warstw na podłoża elastyczne. Otrzymane wyniki zostały porównane z danymi dla podłoży sztywnych.
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Facile synthesis and characterization of graphene and N-doped graphene by CVD method from liquid precursors for promising electrode materials
PublikacjaIn this study, high-quality and few-layered graphene was synthesized using the chemical vapor deposition (CVD) method from liquid sources. Two different liquid carbon sources, pyridine, and benzene, were used and deposited on nickel foam under heat conditions using a bubbler in a quartz tube. X-ray diffraction (XRD) and Raman analysis confirmed the crystalline properties of graphene and N-doped graphene, demonstrating the high...
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ZnFe2O4/ZnO nanoparticles obtained by coprecipitation route, XPS and TEM study
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Enhanced Electrochemical Performance of MnCo1.5Fe0.5O4Spinel for Oxygen Evolution Reaction through Heat Treatment
PublikacjaMnCo1.5Fe0.5O4 spinel oxide was synthesized using the sol−gel technique, followed by heat treatment at various temperatures (400, 600, 800, and 1000 °C). The prepared materials were examined as anode electrocatalysts for watersplitting systems in alkaline environments. Solid-state characterization methods, such as powder X-ray diffraction and X-ray absorption spectroscopy (XAS), were used to analyze the materials’ crystallographic...
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ALTERNATIVE, DIRECT SYNTHESIS METHOD OF THE CERAMIC SOLID SOLUTIONS BASED ON BaTiO3 THROUGH A HIGH ENERGY BALL MILLING
PublikacjaPolycrystalline samples BaTiO3 and the solid solutions Ba0.9Sr0.1TiO3, Ba0.9Sr0.1Ti0.9Sn0.1O3, Ba0.9Sr0.1Ti0.8Sn0.2O3 were obtained by means of a mechanochemical treatment based on the high-energy ball milling technique and next a high temperature solid state reaction method. The influence of synthesis condition on microstructural, dielectric and ferroelectric properties of obtained solid solutions were investigated. The structure...
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Development of iron doped strontium titanates as oxygen electrode for solid oxide fuel cells
PublikacjaProducing efficient solid oxide fuel cells (SOFC) without the use of harmful elements is one of the current challenges. Increasing the safety of people and reducing production costs is possible, among others, thanks to the use of iron doped strontium titanates as porous oxygen electrodes. In this thesis, the results of research on iron doped strontium titanates as potential oxygen electrodes for SOFC are presented. The research...
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Fabrication of ILs-Assisted AgTaO3 Nanoparticles for the Water Splitting Reaction: The Effect of ILs on Morphology and Photoactivity
PublikacjaThe design of an active, stable and ecient photocatalyst that is able to be used for hydrogen production is of great interest nowadays. Therefore, four methods of AgTaO3 perovskite synthesis, such as hydrothermal, solvothermal, sol-gel and solid state reactions, were proposed in this study to identify the one with the highest hydrogen generation eciency by the water splitting reaction. The comprehensive results clearly show that...
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Fabrication and Structural Properties of LaNb 1‐x As x O 4 Ceramics
PublikacjaLanthanum niobate substituted with arsenic was synthesized by three methods: solid state reaction from binary oxides and two different methods combining co-precipitation and solidstate reaction. In the first of the combined methods LaNb1- xAsxO4 was synthesized from LaAsO4, obtained from coprecipitation method, and lanthanum and niobium oxides. In the second LaNbO4 was first synthesized from binary oxides and then mixed with LaAsO4...
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Impact of strontium non-stoichiometry of SrxTi0.3Fe0.7O3-δ on structural, electrical, and electrochemical properties for potential oxygen electrode of intermediate temperature solid oxide cells
PublikacjaThis work presents the results of a comprehensive study on the impact of the A-site non-stoichiometry of SrxTi0.3Fe0.7O3-δ (x = 0.90, 0.95, 1.00, 1.05) ceramics on their physicochemical properties. The materials were fabricated by the conventional solid-state reaction method and their structure was determined by X-ray diffractometry, X-ray photoelectron spectroscopy and electron microscopy. Their sintering and thermal expansion...
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Enhanced electrochemical performance of partially amorphous La0.6Sr0.4CoO3-δ oxygen electrode materials for low-temperature solid oxide cells operating at 400 °C
PublikacjaThis work evaluates partially amorphous La0.6Sr0.4CoO3-δ (LSC) as a potential oxygen electrode for lowtemperature solid oxide cells. LSC was deposited using the spin-coating technique onto Ce0.8Gd0.2O2-δ (CGO) substrates. The optimal oxygen electrode thickness was determined as 500 nm. The electrochemical impedance spectroscopy (EIS) study showed a significant improvement in oxygen reduction/oxidation reaction kinetics when annealing...
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Electrochemical properties of porous Sr0.86Ti0.65Fe0.35O3 oxygen electrodes in solid oxide cells: Impedance study of symmetrical electrodes
PublikacjaThis work evaluates porous Sr0.86Ti0.65Fe0.35O3 (STF35) as a possible oxygen electrode material for Solid Oxide Cells. The powder synthesis was performed by solid state method. Characterization included DC electrical conductivity study of sintered bulk samples and impedance spectroscopy study of symmetrical electrodes deposited on gadolinium doped ceria substrates. Measurements were carried out in atmospheres with different pO2...
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The influence of synthesis method on the microstructure and catalytic performance of Y 0.07 Sr 0.93 Ti 0.8 Fe 0.2 O 3-δ in synthetic biogas operated solid oxide fuel cells
PublikacjaThe Y0.07Sr0.93Ti0.8Fe0.2O3-δ (YSTF) material was fabricated using three different synthesis methods: modified polymer precursor method (MPP), Pechini method and a solid state reaction method. It was applied as an anode catalytic material for biogas reforming in solid oxide fuel cells. Clear differences in the microstructure of fabricated catalytic layers were found, mainly with respect to a grain size and distribution of grains....
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Application of Impedance Spectroscopy for Bi1−xNdxFeO3 Ceramics Characterization
PublikacjaIn the present paper the synthesis conditions for fabrication of Bi1−xNdxFeO3 ceramics are reported. The single phase polycrystalline samples of Bi1−xNdxFeO3 were prepared by standard solid state reaction method from the mixture of oxides viz.: Bi2O3, Fe2O3 and Nd2O3. The samples were characterized by impedance spectroscopy in the frequency range 10Hz – 1MHz at room temperature.
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Superconductivity in the niobium-rich compound Nb5Se4
PublikacjaThe niobium rich selenide compound Nb5Se4 was synthesized at ambient pressure by high-temperature solid–state reaction in a sealed Ta tube. Resistivity and heat capacity measurements reveal that this compound is superconducting, with a Tc = 1.85K. The electronic contribution to the specific heat γ and the Debye temperature are found to be 18.1 mJmol−1K−2 and 298 K respectively. The calculated electron-phonon coupling constant λep...
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Magnetic properties of α-KCoPO4 compound with a chiral polar crystal structure
PublikacjaWe have obtained polycrystalline samples of a metastable α variant of KCoPO4 by low temperature (350–400 °C) solid state metathesis reaction of potassium oxalate and ammonium cobalt orthophosphate. The material crystallizes in a polar chiral structure (sg. P63, no. 173). Measurements of magnetic properties reveal antiferromagnetic interactions and no ordering observed down to T = 1.9 K, well below the Weiss temperature |Θcw| =...
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Fabrication, structural and electrical properties of Sr(V,Nb)O 3-δ perovskite materials
PublikacjaThe SrV1-xNbxO3-δ materials with different niobium content in perovskite B-sublattice were prepared by a solid-state reaction process. The microstructure and phase compositions of obtained samples were analyzed by the X-ray diffraction technique (XRD) and scanning electron microscopy (SEM). The electrical conductivity of samples was measured by a DC 4-wire method in range of 100–600 °C in different gas conditions. The oxidation...
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Induction of chirality in 4,4'-azopyridine by halogen-bonding interaction with optically active ditopic donors
PublikacjaOptically active ditopic halogen bond donors bearing two 4-iodotetrafluorophenyl groups were obtained by reaction of chiral diols with iodopentafluorobenzene. Co-crystallization of these donors with anti-4,4′-azopyridine afforded binary complexes containing infinite chains of the alternating component molecules connected by halogen bonds. The solid state CD measurements confirmed that complexation induces optical activity of the...
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From polymer waste to potential main industrial products: Actual state of recycling and recovering
Publikacjalastics have become widely used materials in everyday life due to their special properties such as durability, easy processing, light-weight and low-cost of production. However, because of their stable and non-biodegradable nature, postconsumer plastics become an issue to the environment. The growing amounts of waste are generated, as plastic products are commonly used only once before disposal. The alternatives of practical techniques...
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Vibrational Properties of LaNb0.8M0.2O4-δ (M=As, Sb, V, and Ta)
PublikacjaLaNb0.8M0.2O4-δ (where M=As, Sb, V, and Ta) oxides with pentavalent elements of different ionic sizes were synthesized by a solid-state reaction method. The vibrational properties of these oxides have been investigated. These studies revealed that the substituent element influences both Debye temperature value as well as the Raman active vibrational modes. Additionally, the low-temperature vibrational properties of LaNb0.8Sb0.2O4-δ...
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New heterometallic Co/Zn, Ag/Co, and Ag/Zn imidazolates: structural characterization and catalytic activity in the oxidation of organic compounds
PublikacjaNanocrystalline powders of monometallic and bimetallic imidazolates of Co, Zn, and Ag were produced by a reaction carried out in water. The powders were characterized by powder X-ray diffraction and the crystal structures of new compounds Ag2ZnIm4 and Ag2CoIm4 (Im = imidazolate) were solved. Heterometallic Co/Zn imidazolates showed the standard ZIF-8 crystal structure while Ag/Zn and Ag/Co systems were isostructural with the copper...
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Electrical and structural properties of Nb-doped SrTiO3
PublikacjaNiobium-doped strontium titanate synthesized via conventional solid-state reaction has been studied. Influence of niobium content on the lattice parameters and electrical conductivity has been reported. Various reduction conditions have been investigated. For samples reduced in hydrogen at 1400°C, a transition from thermally activated to metallic behavior has been observed. Maximum electrical conductivity (ca. 55 Scm−1 at 650°C)...
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Syntheses and structures of the first terminal phosphanylphosphido complexes of molybdenum(IV)
PublikacjaThe reactions of R2P-P(SiMe3)Li (R = tBu, iPr2N) with [Cp2MoCl2] yield terminal phosphanylphosphido complexes formally via the insertion of the phosphinidene P-atom into the C - H bond of a cyclopentadienyl ring and the migration of the hydrogen atom or SiMe3 moiety to the molybdenum centre. Solid state structures of [Cp(C5H4P-PtBu2)MoH], [Cp(C5H4P-PtBu2)Mo(SiMe3)] and [Cp{C5H4P-P(NiPr2)2}Mo(SiMe3)] were established by single crystal...
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Microwave-assisted synthesis of zinc derivatives of potato starch
PublikacjaZincatated potato starch was prepared in a solid-state, microwave-assisted reaction using generated in situ sodium tetrahydroxozincate [Na2Zn(OH)4]. For comparison, zincatation of starch was also carriedout on convectional heating. Depending on the irradiation conditions, the products of either mono- or crosslinking esterification were formed. Higher power applied at shorter exposition offered products ofmonoesterification, and...
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Reactions of Lithiated Diphosphanes R2P-P(SiMe3)Li (R = tBu, iPr, iPr2N, Et2N) with [Cp2WCl2]. Syntheses and Structures of the First Terminal Phosphanylphosphido Complexes of Tungsten(IV)
PublikacjaReactions of R2P−P(SiMe3)Li (R = tBu, iPr, iPr2N, Et2N) with [Cp2WCl2] yield terminal phosphanylphosphido complexes [Cp(C5H4P-PR2)WH] or [Cp{C5H4P-PR2}-W(SiMe3)] by way of a hydrogen or SiMe3 migration to tungsten. The solid-state structures of [Cp(C5H4P−PtBu2)-WH] and [Cp(C5H4P-PNEt2)WH] were established by singlecrystalX-ray diffraction. Two stereoisomers of [Cp(C5H4P−PtBu2)WH] were identified by solution NMR spectroscopy. Reaction...
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General route for the synthesis of terminal phosphanylphosphido complexes of Zr(IV) and Hf(IV): Structural investigations of the first zirconium complex with a phosphanylphosphido ligand
PublikacjaReactions of R2P-P(SiMe3)Li with [Cp2MCl2] (M = Zr, Hf) in hydrocarbons yield the related terminal phosphanylphosphidocomplexes [Cp2M(Cl){(Me3Si)P-PR2-jP1}] (R = iPr and tBu). The solid state structures of [Cp2M(Cl){P(SiMe3)-PiPr2-jP1}] (M = Zr, Hf) were established by single crystal X-ray diffraction studies. The phosphido-P atoms adopt almost planar geometries and the phosphanyl P atoms adopt pyramidal geometries. The reaction...
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Electric and magnetic properties of Lanthanum Barium Cobaltite
PublikacjaThe cubic Ba0.5La0.5CoO3‐δ was synthesized using solid state reaction. The structural properties were determined by the simultaneous refinement of Synchrotron Powder X‐ray Diffraction and Neutron Powder Diffraction data. Iodometric titration was used to examine the oxygen stoichiometry and average cobalt oxidation state. Low‐temperature magnetic studies show soft ferromagnetic character of fully oxidized material, with θP = 198(3)...