Lara Righi

Synthesis, characterisation and X-ray crystal structure of copper(II) complexes with unsymmetrical tetradentate Schiff base ligands: first evidence of Cu(II) catalysed rearrangement of unsymmetrical to symmetrical complex

Abstract The mononuclear copper(II) complexes, [CuL1](ClO4) (1), and [CuL2](ClO4) (2) with unsymmetrical quadridentate Schiff base ligands derived from the 1:1:1 condensation of 2,4-pentanedione, pyridine-2-carboxaldehyde and 1,2-ethanediamine (HL1) or 1,3-propanediamine (HL2) have been prepared and characterised. Complex 2 undergoes Cu(II)/H+ catalysed rearrangement to [CuL3](ClO4)2 (3) where L3 is a symmetrical tetradentate Schiff base involving 1,3-propanediamine and pyridine-2-carboxaldehyde. Structures of all the three compounds have been verified by single crystal X-ray analysis. The geometry around Cu(II) is square-planar in 1 and 2 whereas that in 3 is distorted octahedral with two axially coordinated perchlorate ions.

Composition and temperature dependence of the magnetocrystalline anisotropy in Ni2+xMn1+yGa1+z (x+y+z=0) Heusler alloys

The composition dependence of magnetic and structural transformations, as well as the temperature and composition dependence of the magnetocrystalline anisotropy, were studied in the martensitic Ni2+xMn1+yGa1+z (x+y+z=0) Heusler alloys. Moving away from the stoichiometric composition, a slight variation, a large reduction, and a marked enhancement, were, respectively, observed for the Curie temperature, the magnetic anisotropy, and the structural (martensitic–austenitic) transformation temperatures.

Influence of Fe in giant magnetoresistance ratio and magnetic properties of La0.7Ca0.3Mn1−xFexO3 perovskite type compounds

In this work polycrystalline perovskite with composition La0.7Ca0.3Fe0.05Mn0.95O3 has been produced by standard ceramic method. A considerable change occurs in magnetic, transport and magnetoresistance properties with respect to the classic composition without Fe. The introduction of a different metal, Fe, in Mn-O layer causes a decrease of about 50 K in the value of TC. In the same way, a decrease of about 10–15% in the average magnetic moment measured at 1 T is also observed. On the other hand, the introduction of Fe does not cause any appreciable change in the value of the lattice parameter. This new compound presents 60% of giant magnetoresistance ratio at 200 K. Magnetization vs. temperature measurements in zero field cooling and field cooling show clear differences at applied fields below 80 kA m−1. Such a behavior, also observed in La0.7Ca0.3MnO3 sample, is not recognizable as a simple ferromagnetic one. A qualitative discussion of the effect in the magnetic and transport properties of these compou...

Reverse magnetostructural transformation in Co-doped NiMnGa multifunctional alloys

We studied the composition dependence of the structural and magnetic properties of Co-doped Ni–Mn–Ga alloys around the Mn-rich composition Ni50Mn30Ga20. By varying the Co and Mn content we have been able to tune the critical temperatures. In particular, in a suitable composition range, the Curie temperature of martensite is lower than Curie temperature of austenite and lower than martensitic transformation temperature, giving rise to a paramagnetic gap between magnetically ordered martensite and austenite and to the occurrence of a reverse magnetostructural transformation.

Structural anomalies at the magnetic transition in centrosymmetric BiMnO3

The structural properties of

Extended investigation of intermartensitic transitions in Ni-Mn-Ga magnetic shape memory alloys: A detailed phase diagram determination

{\mathrm{BiMnO}}_{3}

Structure, magnetic and transport properties in perovskites

were determined from neutron powder diffraction data as a function of temperature and magnetic field. The structure at all temperatures was found to be centrosymmetric with space group

Synthesis, crystal structure and thermochromism of benzimidazolium tetrachlorocuprate: (C7H7N2)2[CuCl4]

C2∕c

Phase transitions and magnetic entropy change in Mn-rich Ni2MnGa alloys

, which is incompatible with ferroelectricity. At

Synthesis, spectral and cyclic voltammetric studies on (4,4′-bipyridyl)bis(di(2-hydroxyethyl)dithiocarbamato)zinc(II) and (4,4′-bipyridyl)bis(bis(N-methyl, N-ethanoldithiocarbamato)zinc(II) and their X-ray crystal structures

{T}_{C}\ensuremath{\simeq}100\phantom{\rule{0.3em}{0ex}}\mathrm{K}