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CECILIA MORTALÒ

DIPENDENTE ALTRO ENTE DI RICERCA
Dipartimento di Ingegneria "Enzo Ferrari"
Docente a contratto
Dipartimento di Ingegneria "Enzo Ferrari"

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Pubblicazioni

2019 - Structural evolution of BaCe0.65Zr0.20Y0.15O3-δ-Ce0.85Gd0.15O2-δ composite MPEC membrane by in-situ synchrotron XRD analyses [Articolo su rivista]
Mortalo, C.; Santoru, A.; Pistidda, C.; Rebollo, E.; Boaro, M.; Leonelli, C.; Fabrizio, M.
abstract

Nowadays, dense ceramic membranes based on mixed ionic and electronic conductors are considered very promising materials for H2 separation at T > 600 °C. Among these, BaCe0.65Zr0.2Y0.15O3-δ-Ce0.85Gd0.15O2-δ (BCZ20Y15-GDC15) composite combine an acceptable H2 flux and good chemical stability under CO2- and H2S-containing atmospheres. However, a clear understanding of its crystal structure, phase stability and mechanical stability under real working conditions could not yet be obtained. In this work, its structural evolution was investigated from room temperature to 800 °C by in-situ synchrotron XRD analyses under dry and wet H2. No chemical interaction between the BCZ20Y15 and GDC15 phases occurred in the composite, thus demontrating its excellent chemical stability under operating conditions. However, some phase transitions were observed for the BCZ20Y15 phase, under both dry and wet H2: i.e., it showed an orthorhombic Imma structure from room temperature to 100 °C, trigonal R-3c up to 700 °C and cubic Pm-3m up to 800 °C. On the other hand, the GDC15 phase did not display any phase transition, remaining in a cubic Fm-3m structure under all tested conditions. Moreover, a synergistic effect of the BCZ20Y15 and GDC15 phases in the volume expansion of the composite was revealed: indeed, BCZ20Y15 and GDC15 lattice expansion rates tend to approach each other in the composite under reducing conditions. This synergistic effect is very important for the mechanical performances of BCZ20Y15-GDC15 composite. The similar expansion rate observed for BCZ20Y15 and GDC15 may reduce the strain and prevent failure of this ceramic membrane under operating conditions.

2007 - New Cyclosiloxanolate Cluster Complexes of Transition Metals [Articolo su rivista]
Mortalo', Cecilia; A., Caneschi; Cornia, Andrea; E., Diana; S., Faranda; V., Marvaud; M., Pizzotti; O. I., Shchegolikhina; Zucchi, Claudia; Palyi, Gyula
abstract

New cyclosiloxanolate transition metal cluster complex derivs. were prepd. PhSiO2K reacted with NiX2 (X2 = Cl2 or acac) to give K2{[η6-(PhSiO2)6]2[μ3-(OH)]2Ni4K4}, a mixed Group 1-group 10 metal complex. PhSiO2Na reacted with Ni(NH3)6I2 to give Na{[η6-(PhSiO2)6]2Ni6(μ6-I)} as the 1st example of encapsulated I- ion in siloxanolate complexes. The macrocyclic Na4{[η12-(PhSiO2)12]Cu4} complex reacted with η6-(1,3,5-C7H8)Cr(CO)3 to give the heterobimetallic adduct Na4{[η12-(PhSiO2)12]Cu4}[Cr(CO)3]3 as one of the rare examples of heterobimetallic complexes with different oxidn. nos. of the metals. The Cu deriv. {[η6-(PhSiO2)6]2Cu6(BuOH)5} reacted in MeOH/CHCl3 (1:6) with Et4NCN to give hexanuclear {[η6-(PhSiO2)6]2Cu6(η2-C3H5N2O2)2}, contg. 2-amino-2-oxoethanimidic acid Me ester monoanion ligands, product of an unexpected C-C coupling reaction. This latter complex was characterized also by x-ray diffraction crystal and mol. structure detn.

2006 - Tuning Anisotropy Barriers in a Family of Tetrairon(III) Single-molecule Magnets with an S=5 Ground State [Articolo su rivista]
S., ACCORSI; A. L., BARRA; A., CANESCHI; G., CHASTANET; CORNIA, Andrea; FABRETTI COSTANTINO, Antonio; D., GATTESCHI; MORTALO', Cecilia; E., OLIVIERI; PARENTI, Francesca; P., ROSA; R., SESSOLI; L., SORACE; W., WERNSDORFER; ZOBBI, Laura
abstract

Tetrairon(III) Single-Mol. Magnets (SMMs) with a propeller-like structure exhibit tuneable magnetic anisotropy barriers in both height and shape. The clusters [Fe4(L1)2(dpm)6] (1), [Fe4(L2)2(dpm)6] (2), [Fe4(L3)2(dpm)6]·Et2O (3·Et2O), and [Fe4(OEt)3(L4)(dpm)6] (4) were prepd. by reaction of [Fe4(OMe)6(dpm)6] (5) with tripodal ligands R-C(CH2OH)3 (H3L1, R = Me; H3L2, R = CH2Br; H3L3, R = Ph; H3L4, R = tBu; Hdpm = dipivaloylmethane). The iron(III) ions exhibit a centered-triangular topol. and are linked by six alkoxo bridges, which propagate antiferromagnetic interactions resulting in an S = 5 ground spin state. Single crystals of 4 reproducibly contain at least two geometric isomers. From high-frequency EPR studies, the axial zero-field splitting parameter (D) is invariably neg., as found in 5 (D = -0.21 cm-1) and amts. to -0.445 cm-1 in 1, -0.432 cm-1 in 2, -0.42 cm-1 in 3·Et2O, and -0.27 cm-1 in 4 (dominant isomer). The anisotropy barrier Ueff detd. by a.c. magnetic susceptibility measurements is Ueff/kB = 17.0 K in 1, 16.6 K in 2, 15.6 K in 3·Et2O, 5.95 K in 4, and 3.5 K in 5. Both |D| and Ueff increase with increasing helical pitch of the Fe(O2Fe)3 core. The 4th-order longitudinal anisotropy parameter B40, which affects the shape of the anisotropy barrier, concomitantly changes from pos. in 1 (compressed parabola) to neg. in 5 (stretched parabola). With the aid of spin Hamiltonian calcns. the obsd. trends were attributed to fine modulation of single-ion anisotropies induced by a change of helical pitch.

2004 - Energy Barrier Enhancement by Ligand Substitution in Tetrairon(III) Single Molecule Magnets [Articolo su rivista]
Cornia, Andrea; FABRETTI COSTANTINO, Antonio; P., Garrisi; Mortalo', Cecilia; D., Bonacchi; D., Gatteschi; R., Sessoli; L., Sorace; W., Wernsdorfer; Barra, A. –. L.
abstract

A dramatic increase of the energy barrier (Ueff) in tetrairon(III) single-mol. magnets can be achieved by simple chem. modification. Site-specific replacement of the six methoxide bridges in [Fe4(OMe)6(dpm)6] (Hdpm = dipivaloylmethane; Ueff/kB = 3.5 K) with two tripodal 1,1,1-tris(hydroxymethyl)ethane (H3thme) ligands affords [Fe4(thme)2(dpm)6] with Ueff/kB = 15.6(2) K and a magnetic relaxation time exceeding 1000 s at T <0.2 K. The prepd. complex is trigonal, space group R-3c, Z = 6, R1 = 0.0370, R2 = 0.1089.

2004 - Self-assembly of High-nuclearity Metal Clusters: Programmed Expansion of a Metallasiloxane Cage to an Octacopper(II) Cluster [Articolo su rivista]
G. L., Abbati; Cornia, Andrea; A., Caneschi; FABRETTI COSTANTINO, Antonio; Mortalo', Cecilia
abstract

The novel octanuclear Cu(II) cluster [Cu6{(PhSiO2)6}2{NCCu(Me6tren)}2(MeOH)4]2+ (1) was isolated as a perchlorate salt by reacting the hexacopper(II) metallasiloxane cage [Cu6{(PhSiO2)6}2(nBuOH)x] (x = 4, 6) with [Cu(Me6tren)CN]ClO4 in a MeOH/CHCl3 mixt. (Me6tren = tris(2-(dimethylamino)ethyl)amine). Crystal data for 1(ClO4)2·MeOH: monoclinic, space group P21/n, a = 16.8490(3), b = 22.2966(4), c = 17.2508(3) Å, β = 94.7658(5)°, Z = 2. The structure comprises a highly distorted hexagonal Cu6 array linked to two [Cu(Me6tren)] units via cyanide bridges. Magnetic measurements reveal that the addn. of the Cu cyanide complexes dramatically affects the magnetism of the Cu6 unit, whose ground spin state changes from S = 3 to S = 0.

2004 - Tuneable Energy Barriers in Tetrairon(III) Single–molecule Magnets [Articolo su rivista]
Cornia, Andrea; FABRETTI COSTANTINO, Antonio; P., Garrisi; Mortalo', Cecilia; D., Bonacchi; R., Sessoli; L., Sorace; A. L., Barra; W., Wernsdorfer
abstract

The tetrairon(III) clusters Fe4(L)2(dpm)6 where Hdpm = dipivaloylmethane and H3L = MeC(CH2OH)3 or PhC(CH2OH)3 were obtained by site-specific replacement of the six methoxide bridges in Fe4(OMe)6(dpm)6. As compared with the parent compd., the new clusters show a much larger anisotropy in the S = 5 ground spin state (D/kB∼-0.6 K vs. -0.3 K) and a higher energy barrier to the reversal of the magnetization.