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Crystal structure, and magnetic and dielectric properties were studied in Ti-doped YFeO3 polycrystalline samples. The crystal structure and chemical state of the Fe/Ti cations were characterized by a combination of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It is found that a narrow solid-solubility limit is achieved (~ 6%) and the d0–ness of Ti4+ is not favored in the YFeO3 matrix. A change in the valence states of Fe and Ti cations explains not only the low solubility limit but also the anomalous increase of the volume cell. Soft magnetic hysteresis curves in the M vs H curves indicate that the weak ferromagnetic contribution prevails for all the studied samples. Furthermore, by means of differential calorimetry (DSC) it was possible to identify the AFM transition which decreases with increasing Ti content. On the other hand, the change of the step-like anomaly to a broad peak in the permittivity (ε′) and loss tangent (tan δ) as Ti content increases resemble to a relaxor ferroelectric transition. The endothermic peak (DSC) around the magnetic transition and the broad peaks in the ε′(T) data seem to indicate the existence of a local polarization coupled with AFM transition at ~ 650 K. Two types of charge carriers were found in the doped systems, oxygen vacancies at high temperatures, and small polarons at low temperatures, respectively. Besides, it is found that the introduction of those charge carriers in the YFeO3 matrix occurs by the change of oxidation state from Fe3+ to Fe2+ through Ti3+. [ABSTRACT FROM AUTHOR]

64Cu is an emerging radionuclide of great interest in personalized nuclear medicine. It is produced by a cyclotron via the reaction 64Ni(p,n)64Cu. This production method increased during the last decades, because small biomedical cyclotrons can be easily installed close to the nuclear medicine department of a hospital. As a matter of fact, 64Ni is a very expensive target material. For this reason, an alternative 64Cu production method was investigated at ENEA by using the quasi-monochromatic 14 MeV fusion neutron beam made available at the Frascati Neutron Generator (FNG) located at the ENEA – Frascati Research Center. In particular, two nuclear reactions were studied: 65Cu(n,2n)64Cu and 64Zn(n,p)64Cu. The radiochemical analysis of the activated samples was performed at the ENEA-NMLNWM laboratory located in ENEA-Casaccia Research Center. The activity measurements were carried out at the ENEA-INMRI, located in the ENEA-Casaccia Research Center, with high metrological level conditions and by assuring their traceability to the 64Cu primary activity standard here developed and maintained. A prediction of the 64Cu production by means of the high-brilliance 14 MeV neutron source named Sorgentina is also discussed. [ABSTRACT FROM AUTHOR]

Among those Fe-based perovskite RBa2Fe3O8+δ which are isomorphous to high-TcRBa2Cu3O7-δ superconductors (R=rare earth and Y), the cubic LaBa2Fe3O8+δ is special in that both its magnetism and resistivity are strongly modified when varying a control parameter such as oxygen concentration (8+δ), La/Ba ratio (1+x/2-x), or applied pressure (p). With the aim of identifying and optimizing those conditions that induce a reduction in its magnetism and resistivity, we synthesized various samples of La1+xBa2-xFe3O8+δ and studied their structure, magnetism, and resistivity as a function of δ, p, and x. In this preliminary report, we show that (i) the cubic, Pm3¯m, structure is stable across the studied ranges, however the lattice a-parameter is reduced on increasing x, δ, or p; (ii) the resistivity is reduced on increasing δ or reducing x; the influence of pressure, on the other hand, is mostly manifested around and below the onset points of charge and magnetic order. (iii) The magnetism is much reduced as compared to that of the heavier RBa2Fe3O8+δ members. We discuss the influence of each of x, δ and p in terms of the Fe ions disproportionation scenario. [ABSTRACT FROM AUTHOR]

DyNi2B2C superconducts at Tc≈6K and orders antiferromagnetically at TN≈10K. Its non-superconducting isomorph DyCo2B2C is a ferromagnet with TC≈6K. With the aim of mapping out the magnetic properties, in particular magnetic structures, of their solid solutions, we synthesized 11B-enriched Dy(CoxNi1-x)2B2C (x=0.2,0.4,0.6,0.8). We investigated the evolution of their magnetic, thermal and transport properties by means of the magnetization, resistivity, specific heat and neutron diffraction techniques. Their crystal structures were confirmed to be ThCr2-Si2-type tetragonal (I4/mmm) phase. The magnetic structure was found to be antiferromagnetic with k0.2 = (0, 0, 1) for x = 0.2; helicoidal with k0.4 = (0, 0, 0.49) and k0.6 = (0, 0, 0.46) for, respectively, x = 0.4 and 0.6 and ferromagnetic with k0.8 = (0, 0, 0) for x = 0.8. We discuss the evolution of such magnetic modes assuming a scenario of an idealized one-dimensional chain of transverse magnetic moments. [ABSTRACT FROM AUTHOR]

In this work, high-pressure electrical resistivity measurements and electronic structure analysis on the intermetallic Mo $$_{2}$$ BC system are presented. Electrical resistivity measurements up to about 5 GPa using a diamond anvil cell on Mo $$_{2}$$ BC revealed that $$T_\mathrm{{c}}$$ decreases in a non-monotonic way. Using Linearized Augmented Plane Wave method based on Density Functional Theory, we investigate the changes in the electronic structure of this compound as a function of pressure. The states at the Fermi level mainly come from the d orbitals of molybdenum atoms. As the pressure increases, the band width is enhanced and the total density of states at the Fermi level decreases. The Fermi surface for this compound possesses a two-dimensional character which prevails under an applied pressure of about 10 GPa. The results are compared with the chemical pressure effects on $$T_\mathrm{{c}}$$ induced by the gradual and non-simultaneous elimination of B and C in the compound. [ABSTRACT FROM AUTHOR]

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