High-pressure synthesis of SeCu1-xZnxO3 perovskites

The SeCu1-xZnxO3 solid solution, with a distorted perovskite-type structure, has been synthesized under high pressures and temperatures. X-ray diffraction analysis indicates that the zinc ions occupy the copper sites, a solid solution being formed. It seems that high-pressure stabilises a small cation such as Se4+ in the A site of the perovskite structure ABO(3) although the material is better described as formed by selenite anions SeO(3) over bar and Cu2+/Zn2+ cations

Crystal chemistry and magnetic properties of SeCu1-xZnxO3 (0-<= x <= 1) perovskites

The effects of zinc substitution in the structural and magnetic properties of the orthorhombic solid solution SeCu1-xZnxO3 have been studied. Rietveld refinements of the X-ray diffraction patterns indicate that the zinc ions occupy the copper sites. This replacement induces some changes in the Cu-O bond lengths and [Cu-O-Cu] bond angles. Magnetization vs temperature measurements show a fast decrease in the Weiss constant that reveals a direct quadratic relationship with the increase of the average [Cu-O-Cu] bond angle. Besides, the introduction of a non-magnetic cation in the B-positions in the structure of SeCu1-xZnO3 system, progressively decreases the ferromagnetic interactions. (C) 2002 Elsevier Science (USA)

Magnetism and the absence of superconductivity in the praseodymium-silicon system doped with carbon and boron

We searched for new structural, magnetic and superconductivity phases in the Pr-Si system using high-pressure high-temperature and arc melting syntheses. Both high and low Si concentration areas of the phase diagram were explored. Although a similar approach in the La-Si system produced new stable superconducting phases, in the Pr-Si system we did not find any new superconductors. At low Si concentrations, the arc-melted samples were doped with C or B. It was found that addition of C gave rise to multiple previously unknown ferromagnetic phases. Furthermore, X-ray refinement of the undoped samples confirmed the existence of the so far elusive Pr3Si 2 phase. © 2013 Elsevier B.V