MASINI , Roberto

Mixed LaREO3 (RE ≡ Dy, Ho, Er, Tm, Yb, Lu) and NdGdO 3 oxides were prepared by thermal decomposition of the corresponding co-precipitated mixed oxalates. The decomposition of La/RE and Nd/Gd oxalates was studied by means of differential thermal analysis and thermogravimetric (DTA-TG) measurements; in particular the last step, consisting of the...

Two different synthetic routes to synthesize the magnetic superconductor RuSr2Gd1.4Ce0.6Cu2O10−ı (Ru- 1222) have been reported as an alternative method to the solid state reaction starting from the oxides of Ru, Gd, Ce, Cu and SrCO3. The 1222-phase has been namely prepared by mixing and reacting proper amounts of: (a) the 1212-phase...

A stability study of perovskitic LaREO3 oxides (RE = Dy, Ho, Er, Tm, Yb, Lu) as a function of temperature was undertaken. A correlation between the Goldschmidt t value and the perovskitic stability field amplitude was found: the latter widens as t increases. Magnetic measurements, performed on all the perovskitic samples, showed that t is also...

A thermal study was performed on the RuSr2GdCu2O8 (Ru-1212) magnetic superconductor phase to investigate the effect of the annealingtreatments in flowing O2 on the stability limit of the phase and on its structural, magnetic and transport properties. DTA-TG measurements were utilized to determine the decomposition process and the dependence of...

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Magnetization measurements and neutron powder diffraction analyses followed by Rietveld refinement have been carried out in order to investigate the magnetic structures of LaYbO3 and LaHoO3. Both compounds exhibit a negative thermal expansion along the a and b axes. In LaYbO3 Yb3+ spins order at 2.4 K according to a FyGz-type structure,...

The crystallographic features of Gd-doped ceria were investigated at the operating temperature of solid oxides fuel cells, where these materials are used as solid electrolytes. (Ce1-xGdx)O2-x/2 samples (x = 0.1, 0.3, 0.5, 0.7) were prepared by coprecipitation of mixed oxalates, treated at 1473 K in air, and analyzed by synchrotron X-ray...

The intermetallic perovskite MgCNi3, superconducting with a Tc of 8 K, is particularly interesting from several points of view: in spite of the large amount of nickel present the compound is not ferromagnetic; nevertheless band structure calculations put in evidence a Van Hove singularity just above the Fermi level suggesting that MgCNi3 is on...

Hexagonal as well as tetragonal rare earth oxycarbonates can act as hosts for optically active ions; hence, the knowledge of the structural modifications occurring when foreign hosts are inserted into the parent compound is of fundamental importance for the design of new phosphors. In this article, a phase stability study of the...

The phase stability of the system Gd2O3-Nd2O3 up to 1350°C was studied. Mixed oxides were synthesized by coprecipitation of mixed oxalates. Depending on the thermal treatment, three possible structures of the oxides, namely the A (hexagonal, P63/mmm), B (monoclinic, C2/m) and C (cubic, Ia3) forms, were obtained. Below 1300°C the system...

The synthesis and physical characterization of single phase polycrystalline samples with composition RuSr2GdCu2O8 has been performed. We report on the electrical and magnetic measurements carried out in order to investigate and relate the properties of this compound subjected to different annealing routes. We show that while intrinsic...

In the search for new intermetallic materials with high thermoelectric performances, the Co–Sb–S ternary system has been explored and polycrystalline CoSbS samples have been prepared by a vapour phase technique starting from the pure elements. The crystal cell of CoSbS belongs to the Pbca space group and shows an orthorhombic structural...

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We report on the structural, electrical and magnetic properties of RuSr2GdCu2O8 samples made by systematic synthesis work so that they differ from one another in number of annealings and sintering temperature. Our aim is to highlight the different behaviours as a consequence of the thermal treatments. In particular, we deal with the onset of...

The crystal and magnetic structures of 10 and 20 nm sized (La1-xCax)MnO3 (x = 0.37, 0.50, 0.75) have been investigated between 5 and 300 K by means of Rietveld refinement of neutron powder diffraction data, coupled with transmission electron microscope observation and magnetization measurements. TEM observation reveals that nanoparticles are...

GdSr2RuCu2O8 has been synthesized using a solid state reaction and has been characterized from the structural and physical points of view. The samples exhibit the well-known superconducting and magnetic behavior; in addition, an orthorhombic modification of the GdSr2RuCu2O8 lattice has been detected by both high resolution transmission electron...

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Structural and microstructural features, as well as thermal and magnetic properties of Yb-doped Gd2O2CO3, were investigated with the aim to clarify the location and the oxidation state of Yb within the structure, and its role in driving the extent of the (Gd1-xYbx)2O2CO3 solid solution. Yb is found in the 3+ oxidation state and it enters the...

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A systematic study on the synthesis of the Ru-1212 compound by preparing a series of samples that were annealed at increasing temperatures and then quenched has been performed. It results that the optimal temperature for the annealing lies around 1060-1065 degreesC; a further temperature increase worsens the phase formation. Structural order is...