Search results for "Ferro"

Influence of uniaxial pressure and aging on dielectric and ferroelectric properties of BaTiO3ceramics

2013

The effect of uniaxial pressure (0–3000 bar) applied parallel to the AC electric field and aging on dielectric and ferroelectric behavior of BaTiO3 ceramics were investigated. Applying uniaxial pressure leads to a reduction of the peak intensity of the electric permittivity (e) of the polarization as well as of the dielectric hysteresis. The peak intensity of e becomes diffused and shifts to a higher temperatures with increasing the pressure. The electrostrictive coefficient Q 11 and differential permittivity were evaluated from the obtained data. We interpreted our results based on the hardening of the soft-mode and domain switching processes under the action of pressure. The aging effect …

Synthesis and Catalytic Use of Polar Phosphinoferrocene Amidosulfonates Bearing Bulky Substituents at the Ferrocene Backbone

2021

International audience; Anionic phosphinoferrocene amidosulfonates bearing sterically demanding t-butyl substituents in positions 3 and 3' of the ferrocene scaffold, viz. rac-(Et3NH)[Fe(η5-tBuC5H3PR2)(η5-tBuC5H3C(O)NHCH2SO3)] (R = phenyl and cyclohexyl) were synthesized by amidation of the corresponding phosphinocarboxylic acids, [Fe(η5-tBuC5H3PR2)(η5-tBuC5H3CO2H)]. These ditopic polar phosphinoferrocenes and their non-t-butylated analogues have been used as lig-ands to prepare zwitterionic (η3-allyl)palladium(II) complexes [Pd(η3-C3H5){Fe(η5-R'C5H3PR2)(η5-R'C5H3C(O)NHCH2SO3)}] (R' = H, tBu, R = Ph, Cy). Depending on the isolation procedure and crystallization condi-tions, some complexes we…

Counter-complementarity control of the weak exchange interaction in a bent {Ni(ii)3 complex with a μ-phenoxide-μ-carboxylate double bridge

2019

We have prepared and structurally characterized a novel {Ni3} bent complex bearing a double μ-phenoxide-μ-carboxylate bridge. Both terminal Ni(ii) sites are symmetry related, offering a simplified exchange interaction scheme. DC magnetic data is consistent with a weak antiferromagnetic interaction between the central and terminal Ni(ii) ions. As expected for a Ni(ii) system, local zero-field splitting is observed, which can be experimentally established. Broken symmetry quantum chemical calculations, as well as ab initio CASSCF-SA-SOC computations that support the magnetic experimental data, were also performed. From the analysis of other reported closely related Ni(ii) systems, a counter-c…

Inhibitoren der Korrosion 30 (1,2) - Vergleichende Studien über das Verhalten bekannter und bisher unbekannter Inhibitoren der Korrosion des Kupfers …

1985

Folgende Verbindungen wurden auf ihre Fahigkeit zur Inhibierung der Korrosion von Kupferproben unter Standardbedingungen uberpruft: Benzotriazol (BTA), 5-Aminotetrazol-monohydrat (5-AT), 2,5-Diphenyl-3-(m-chlorphenyl)-tetrazolium-nitrat (Tetrazin-B), α- und β-Naphthylamin, Phenylthioharnstoff, Xanthanwasserstoff, 2-Mercaptothiazolin (2-MT) und Kupferron. Folgende Messungen wurden durchgefuhrt: Bestimmung der Geschwindigkeit der Sauerstoffaufnahme im Schuttelversuch und pH-statische Verfolgung des Korrosionsverlaufs in Abhangigkeit (a) von der Konzentration des Inhibitors, (b) dem Verteilungszustand der Kupferprobe (Korn, Staub, Blech), (c) der Anwesenheit von Cu2+-Ionen und (d) dem pH-Wert.…

Evaluación del efecto rejuvenecedor de bio-materiales sobre ligantes para mezclas con alto contenido de asfalto recuperado

2017

The interest in using bio-materials in pavement engineering has grown significantly over the last decades due to environmental concerns about the use of non-recoverable natural resources. In this paper, bio-materials are used together with Reclaimed Asphalt (RA) to restore some of the properties of the aged bitumen present in mixtures with high RA content. For this purpose, two bio-materials are studied and compared to conventional and polymer modified bitumens. Blends of these materials with RA bitumen were produced and studied to simulate a 50% RA mixture. The rejuvenating effect of the two bio-materials on RA has been assessed and compared with the effect of the conventional binders. App…

A Molecular Metal Ferromagnet from the Organic Donor Bis(ethylenedithio)tetraselenafulvalene and Bimetallic Oxalate Complexes

2003

A new dual-function hybrid molecular material has been obtained from the organic donor bis(ethylenedithio)tetraselenafulvalene and the honeycomb oxalate-based bimetallic network [MnCr(ox)3]-. This multilayer material consists of layers of the inorganic anionic 2D network, responsible for the appearance of ferromagnetic ordering below 5.3 K, alternating with segregated layers of the organic cation radical responsible for the transport properties:  metal-like conductivity is observed from room temperature down to 150 K.

Supramolecular Adducts of Ferrocene and Five Bile Acid Derived Triolides

1997

Formation of supramolecular adducts of ferrocene (guest) and cyclic head-to-tail trimers (hosts) derived from bile acid: 3α-hydroxy-5β-cholan-24-oic acid triolide (1), 3α-hydroxy-7-oxo-5β-cholan-24-oic acid triolide (2), 3α-hydroxy-12-oxo-5β-cholan-24-oic acid triolide (3), 3α-hydroxy-7α-trifluoroacetoxy-6β-cholan-24-oic acid triolide (4) and 3α-hydroxy-12α-TFA-5β-cholan-24-oic acid triolide (5) (TFA = trifluoroacetoxy) have been studied by 1H NMR. The best computer-assisted data fitting on the 1H-NMR chemical shift data was given by a 1:2 (guest/host) association model. The association constants vary in the range 170–990 M−1, 7-oxo-substituted triolide 2 and 12α-TFA triolide 5 showing the …

Metallosupramolecular compounds based on Cu(ii)/oxalate/twisted NSSN ligands showing a new in situ S–C bond cleavage

2013

Four new complexes, [Cu2(C2O4) 2(SCS)]·3H2O (1), [Cu2(C 2O4)3(SCSH)2]·H2O (2), [Cu(C2O4)(SS)2]·3H2O (3) and [Cu(C2O4)(SS)]·6H2O (4) [where SCS = bis(4-pyridylthio)methane and SS = 4,4′-dipyridyldisulfide], have been synthesized by the reaction of the SS and SCS ligands with the corresponding copper(ii) oxalate salt. The different synthetic conditions allowed control of the preparation of a 3D open metal-organic framework in 1, a dinuclear zwitterionic molecular compound in 2 and one- and two-dimensional (1D and 2D) coordination polymers in 3 and 4, respectively. Compound 4 was also obtained by in situ transformation of the dithioether ligand (SCS) to the disulfide ligand (SS) under hydrothe…

Thermomagnetic Materials: Thermomagnetic Properties Improved by Self-Organized Flower-Like Phase Separation of Ferromagnetic Co2Dy0.5Mn0.5Sn (Adv. Fu…

2012

The magnetic properties of ferrocene based macromolecules

1993

Abstract Magnetic susceptibility data for conjugatively linked biferrocenes and a methylene bridged ferrocene polymer are presented. In 9,10-di((2-ferrocenyl)vinyl)anthracene a rigid divinylanthracene bridge is connecting two ferrocene units, and the oxidation of both iron centers leads to an antiferromagnetic coupling. In contrast, ferromagnetic coupling between iron centers is indicated for 2,2'-cis,trans-di((2-ferrocenyl)vinyl)biphenyl, where a twist around the phenyl-phenyl bond in the divinylbiphenyl bridging molecule is likely to occur.