Search results for "Ferro"
showing 10 items of 2451 documents
Performances of symmetrical achiral ferrocenylphosphine ligands in palladium-catalyzed cross-coupling reactions: A review of syntheses, catalytic app…
2007
Abstract Ferrocene derivatives bearing donor atoms led to the generation of several classes of metallo-ligands, which collectively show an impressive diversity of applications, especially in metal-catalyzed modern organic reactions. Based on the impetus provided by the use of the diphosphine 1,1′-bis(diphenylphosphino)ferrocene (dppf) the investigations directed towards the synthesis of new ferrocenylphosphines remain of fundamental and industrial interest. The present review aims to describe the performances in palladium-catalyzed cross-coupling reactions of symmetrical achiral ferrocenylphosphine ligands, mainly diphosphines. We specifically choose to restrict our review efforts to these …
Exceedingly Fast Oxygen Atom Transfer to Olefins via a Catalytically Competent Nonheme Iron Species
2016
El mateix article està publicat en alemany a l'edició alemanya d' 'Angewandte Chemie' (ISSN 0044-8249, EISSN 1521-3757), 2016, vol. 128, núm. 21, p.6418–6422. DOI http://dx.doi.org/10.1002/ange.201601396 The reaction of [Fe(CF3SO3)2(PyNMe3)] with excess peracetic acid at −40 °C leads to the accumulation of a metastable compound that exists as a pair of electromeric species, [FeIII(OOAc)(PyNMe3)]2+ and [FeV(O)(OAc)(PyNMe3)]2+, in fast equilibrium. Stopped-flow UV/Vis analysis confirmed that oxygen atom transfer (OAT) from these electromeric species to olefinic substrates is exceedingly fast, forming epoxides with stereoretention. The impact of the electronic and steric properties of the subs…
Prediction of Airport Pavement Moduli by Machine Learning Methodology Using Non-destructive Field Testing Data Augmentation
2022
For the purpose of the Airport Pavement Management System (APMS), in order to optimize the maintenance strategies, it is fundamental monitoring the pavement conditions’ deterioration with time. In this way, the most damaged areas can be detected and intervention can be prioritized. The conventional approach consists in performing non-destructive tests by means of a Heavy Weight Deflectometer (HWD). This equipment allows the measurement of the pavement deflections induced by a defined impact load. This is a quite expensive and time-consuming procedure, therefore, the points to be investigated are usually limited to the center points of a very large mesh grid. Starting from the measured defle…
Modeling of trapped charge effects in ferroelectrics: application to piezoactuators
1997
The strain response of lead zirconate titanate piezoelectric multilayer actuators have been measured up to 10 7 N/m 2 stress and the 3.10 6 V/m periodic unipolar driving voltage. An additional nonstationary strain component is detected. This effect is explained in terms of a simple solution of polarization kinetics specific for unipolar driving voltage. Preliminary experimentally assertions are given for space charge effects which manifest itself in the strain as well as charge plot after removing the mechanical load. It demonstrates that the static load free equilibrium of the actuator is not complete and the charge recently supported by the piezo voltage and then trapped forms a nonunifor…
STRONTIUM CONCENTRATION DEPENDENCE OF SELECTED STRUCTURAL AND MECHANICAL PROPERTIES OF POLYCRYSTALLINE Ba1−XSrXTiO3
2009
ABSTRACT Microstructure and material constants such as Young modulus E, shear modulus G, Poisson ratioν of polycrystalline ferroelectric materials Ba1-xSrxTiO3 for 0≤x≤0.4 were investigated to determine their dependence on strontium concentration. The performed investigations showed that the material is chemically homogeneous. It was found that the strontium concentration had no significant influence on the grain size. The highest value of Young's modulus is observed for Ba0.6Sr0.4TiO3 sample. The performed investigations of mechanical properties made it possible to evaluate the usability of this material for manufacturing transducers and sensors which could work under load.
Dielectric and Elastic Parameters of LixNa1-xTa0.1Nb0.9O3 Ferroelectric Solid Solution Ceramics
2011
Results of the studies of electric and elastic parameters as functions of concentration in ferroelectric LiхNa1-хTa0.1Nb0.9O3 (x = 0–0.16) solid solutions and comparative studies of the elastic properties by acoustic and contact probe techniques are reported. The electric and elastic properties of LiхNa1-хTa0.1Nb0.9O3 solid solutions are shown to be rather sensitive to structural distortion at concentration-induced structural phase transitions. The values of elastic modules obtained from acoustic measurements are found to be in good agreement with those obtained by contact probe techniques.
Synthesis and reactivity of P-ferrocenylalkylidenephosphanes and related iminophosphanes and diphosphenes
1997
P-Ferrocenyl-substituted alkylidenephosphanes have been prepared and characterized spectroscopically. Their ready conversion to the corresponding acylphosphanes and 1,2-diacyldiphosphanes, as well as a new type of phosphirene synthesis are presented. The X-ray structure of the tetraferrocenyl-substituted diacyldiphosphane has been investigated. Furthermore, P-ferrocenyl iminophosphanes and their complexation behaviour are described. Diferrocenyldiphosphene, which is known to be unstable, has been stabilized by complexation; this has been confirmed by NMR-spectroscopy and X-ray structure analysis.
Thermal, electric and spin transport in superconductor/ferromagnetic-insulator structures
2019
A ferromagnetic insulator (FI) attached to a conventional superconductor (S) changes drastically the properties of the latter. Specifically, the exchange field at the FI/S interface leads to a splitting of the superconducting density of states. If S is a superconducting film, thinner than the superconducting coherence length, the modification of the density of states occurs over the whole sample. The co-existence of the exchange splitting and superconducting correlations in S/FI structures leads to striking transport phenomena that are of interest for applications in thermoelectricity, superconducting spintronics and radiation sensors. Here we review the most recent progress in understandin…
Antiferromagnetism and the node structure of the superconducting order parameter of UPd Al
2000
The node structure of the superconducting order parameter of the heavy-fermion system is analyzed within the weak-coupling theory. A pairing interaction induced by the exchange of antiferromagnetic spin excitations is assumed as suggested by recent inelastic neutron scattering experiments and tunneling spectroscopy. The multi-sheeted Fermi surface is taken into account. Based on a model susceptibility for the simple antiferromagnetic structure of , line nodes result at the rim of the magnetic Brillouin zone.
Hybrid molecular conductors
2005
One of the most important trends in the field of organic conductors aims towards the design of hybrid materials, following the strategy of combining in a single compound organic cationic radicals able to give rise to conducting architectures with functional molecular anions able to add a second physical property of interest. Ferromagnetic metals, magnetic superconductors, chiral conductors and switchable conductors are some of the most recent and spectacular materials obtained from this approach. The design and physical studies of some relevant examples are discussed and highlighted.