Search results for "Ferro"
showing 10 items of 2451 documents
Study of Tetragonal Phase in 0.4Na1/2Bi1/2TiO3-(0.6-x)SrTiO3-xPbTiO3Solid Solutions by Second-Harmonic Generation
2015
Description of the local symmetry of relaxor ferroelectrics, especially in connection with nature of polar nanoregions, is one of the key questions in research of relaxor ferroelectrics. Unlike such well-known relaxor ferroelectrics as PbMg1/3Nb2/3O3 and (Pb,La)(Zr0.65Ti0.35)O3, ternary solid solutions 0.4Na1/2Bi1/2TiO3-(0.6-x)SrTiO3-xPbTiO3 show clear coexistence of phases of tetragonal and cubic symmetry, which is established by x-ray diffractometry. Since the second-harmonic generation spectroscopy is a sensitive tool in determination of deviation from symmetry, containing a centre of inversion, it is used as an additional method in characterization of structure in 0.4Na1/2Bi1/2TiO3-(0.6…
Magnetic properties of Co–Al, Ni–Al, and Mg–Al hydrotalcites and the oxides formed upon their thermal decomposition
2002
The magnetic behaviour of Co–Al, Ni–Al, and Mg–Al hydrotalcites (HTlc) with a M2+/Al3+ molar ratio of 3 and carbonates in the interlayer, as well as the mixed oxides obtained after calcination at 823 K for 5 h, has been investigated by DC and AC magnetic susceptibility measurements and isothermal magnetisation. The samples were also characterised by ICP-OES and XRD. The magnetic measurements show that Co–Al and Ni–Al HTlcs behave as ferromagnets, with ordering temperatures of approximately 6–7 K in both cases, and displaying hysteresis loops at 2 K with coercive fields of 4.2 and 5.5 mT, respectively, whereas the Mg–Al-HTlc shows the expected diamagnetic behaviour. A solid solution of cobal…
CHARACTERIZATION OF RUBBERIZED ASPHALT FOR RAILWAYS
2018
Rubberized asphalt mixtures are regarded as a solution for improving the strength of the rail-track section. The recycled rubber has become an enhancer of the modified bituminous mixtures. In this work, it has been shown as a sustainable improvement option in HMA mixes due to the elastic behavior exposed by the rubber particles. The impact of thermal susceptibility on the mechanical properties of the railway bituminous sub-ballast layer has served to the advanced measurement of the thermal cycles inside the rail track. Different simulations following the Kentrack and Kenpave software were employed to be effective with the best mix-design for railways. According to weather situation, reviewe…
Synthesis, crystal structure, thermal and magnetic properties of [Mn(H2O)6][Cu(pdta).2H2O (pdta= 1,3-propylenediamine-N,N,N',N'-tetraacetate
2000
[EN] On mixing concentrated aqueous solutions of pdta, Cu(II) and Mn(II) in the ratio 1:1:1 at pH 4.5, single crystals of the complex [Mn(H2O)6][Cu(pdta)]·2H2O (1) (pdta=1,3-propylenediamine-N,N,N'N'-tetraacetate) were obtained. X-ray structural analysis revealed that in the anion [Cu(pdta)]2- the coordination polyhedron around the Cu(II) ion can be described as a tetragonaly distorted CuN2O4 octahedron, whereas the cation [Mn(H2O)6]2+ can be described as a very regular MnO6 octahedron. Thermogravimetric analysis shows that at 110°C compound 1 loses its eight water molecules yielding the anhydrous compound [MnCu(pdta)] (2). Variable-temperature magnetic susceptibility measurements indicate …
Solvent Modulated Assembly of Two Ni(II) Complexes: Syntheses, Structures and Magnetic Properties
2016
A dinuclear [Ni2(L)2(DMSO)2(MeOH)2] (1) and a tetra-nuclear [Ni4(L)4(DMF)2(H2O)2].DMF (2) Ni(II) complexes have been prepared by treating nickel nitrate hexahydrate with the Schiff base ligand H2L (H2L=(E)-2-(2-hydroxybenzyliden)amino-4-nitrophenol) in a one-pot reaction. Complex 1 was obtained after recrystallization of the precipitate from the reaction with a 1:1:1 mixture of DMSO/CH2Cl2/MeOH. In contrast, the tetrameric complex 2 was obtained after slow evaporation of the filtrate. Both complexes were characterized by analytical, thermogravimetric, optical and magnetic techniques. The solid state molecular structures of 1 and 2 were determined by single crystal X-ray crystallography. Com…
Effect of some additives on the reactions in fly ASH-Ca(OH)2system
2004
Differential thermal analysis and thermogravimetry were used to evaluate the effect of some additives, such as CaSO4, CaCl2 and silica fume amorphous silica from ferrosilicon synthesis on the mechanism and kinetics of reactions occurring in fly ash-Ca(OH)2 system. The accelerating role of these additives was demonstrated from the data relating to Ca(OH)2 consumption in hydrated pastes, determined by TG measurements.
Computer simulation of ferroelectric property changes in PLZT ceramics under neutron irradiation
2001
The response of ferroelectric materials to high energy irradiation is of great interest because of their possible application in radiation environments such as thermonuclear reactors. In the present work a physical model for the defect evolution in PLZT ceramics under neutron irradiation and annealing is proposed. The influence of the defect system on the ferroelectric properties of these materials has been investigated. Satisfactory agreement between the theoretical estimated oxygen defect concentration after irradiation and annealing and the experimentally determined polarization has been obtained.
Highly Functionalized Ferrocenes
2020
International audience; Ferrocene is unique among organometallic compounds, and serves notably as a versatile platform towards the production of ligands useful to promote transition metals chemistry. A general limiting aspect of the synthesis of ferrocene derivatives is the efficient access to sophisticated highly functionalized polysubstituted ferrocenes, i. e. bearing four or more substituents replacing hydrogen atoms on the cyclopentadienyl rings. These ferrocene derivatives can bear various functional or/and structuring spectator substituents. Their preparation involves synthetic difficulties resulting from the need of multiple functionalizations coexisting altogether, and satisfying fu…
Photomagnetism of a Series of Dinuclear Iron(II) Complexes
2009
International audience; The photomagnetic properties of a series of [{Fe(NCS)(py-X)}2(bpypz)2] (NCS=thiocyanate, py=pyridine, X=4-Mepy, py, 3-Mepy, 3-Clpy and 3-Brpy, and bpypz=3,5-bis(pyridine-2-yl)pyazolate) binuclear complexes are close to the antiferromagnetic response of [{Fe(NCS)(3,5-dmpy)}3(bpypz)2] (3,5-dmpy=3,5-dimethylpyrazine), which is characterised by two iron(II) metal ions in a high-spin (HS) electronic configuration . This paper describes the photomagnetic properties of a series of binuclear iron(II) complexes belonging to the [{Fe(NCS)(py-X)}2(bpypz)2] family (NCS=thiocyanate; py=pyridine; bpypz=3,5-bis(pyridine-2-yl)pyrazolate; and py-X=4-Mepy (1), py (3), 3-Mepy (4), 3-Cl…
Synthesis, crystal structure and magnetic properties of the dinuclear manganese(II) complexes [Mn2(bpym)3(NCX)4] (bpym = 2,2′-bipyrimidine; X = S, Se)
1997
Abstract The dinuclear manganese(II) compounds of formula [Mn2(bpym)3(NCX)4], where bpym = 2,2′-bipyrimidine and X = S(1) and Se(2), have been prepared and their crystal structures determined by X-ray diffraction methods. 1 and 2 are isostructural. They crystallize in the triclinic P 1 space group with Z = 1, γ ( Mo K α ) = 0.71073 A , T = 295 K and a = 9.141(2), b = 9.248(2), c = 11.733(2) A , α = 74.88(2), β = 80.29(2), γ = 61.03(2)°, V = 836.7(3) A 3 , D c = 1.621 g cm −3 , M r = 316.7, F(000) = 412, and μ( Mo K α) = 10.54 cm −1 for 1 and a = 9.244(2), b = 9.278(2) A , c = 11.887(2) A , α = 75.19(2), β = 80.83(2), γ = 61.54(2)°, V = 865.7(3) A 3 , D c = 1.926 g cm −3 , M r = 1004.3, F(00…