Synthesis and characterization of zinc(II), palladium(II) and platinum(II) complex with 2-[1-(2-pyridinyl)ethylidene] oxamohydrazide. The crystal structure of bis{2-[1-(2-pyridinyl)ethylidene]oxamohydrazido}zinc(II) trihydrate

Complexes of Zn(II), Pd(II) and Pt(II) with 2-[1-(2-pyridinyl)ethylidene]oxamohydrazide (Hapsox) were synthesized and their structures were determined. All the complexes are of a neutral type with two apsox ligands coordinated to Zn(II) and one apsox ligand coordinated to Pd(II) or Pt(II). In each case, the polydentate was coordinated via pyridine and hydrazone nitrogens and a-oxyazine oxygen, forming an octahedral geometry around Zn(II), and a square planar one around Pd(II) and Pt(II). The structure determination was performed by IR, 1H-NMR and 13C-NMR spectroscopy, and for the Zn(II) complex by X-ray structure analysis

Cation ordering, ferrimagnetism and ferroelectric relaxor behavior in Pb(Fe1-xScx)(2/3)W1/3O3 solid solutions

Ceramic samples of the multiferroic perovskite Pb(Fe1-xScx)(2/3)W1/3O3 with 0 <= x <= 0.4 have been synthesized using a conventional solid-state reaction method, and investigated experimentally and theoretically using first-principle calculations. Rietveld analyses of joint synchrotron X-ray and neutron diffraction patterns show the formation of a pure crystalline phase with cubic (Fm3(_)m) structure with partial ordering in the B-sites. The replacement of Fe by Sc leads to the increase of the cation order between the B and B '' sites. As the non-magnetic Sc3+ ions replace the magnetic Fe3+ cations, the antiferromagnetic state of PbFe2/3W1/3O3 is turned into a ferrimagnetic state reflecting the different magnitude of the magnetic moments on the B ' and B '' sites. The materials remain ferroelectric relaxors with increasing Sc content. Results from experiments on annealed and quenched samples show that the cooling rate after high temperature annealing controls the degree of cationic order in Pb(Fe1-xScx)(2/3)W1/3O3 and possibly also in the undoped PbFe2/3W1/3O3

Cation ordering, ferrimagnetism and ferroelectric relaxor behavior in Pb(Fe1−xScx)2∕3W1∕3O3Pb(Fe_{1−x}Sc_{x})_{2∕3}W_{1∕3}O_{3} solid solutions

Ceramic samples of the multiferroic perovskite Pb(Fe1−xScx)2∕3W1∕3O3 with 0 ≤ x ≤ 0.4 have been synthesized using a conventional solid-state reaction method, and investigated experimentally and theoretically using first-principle calculations. Rietveld analyses of joint synchrotron X-ray and neutron diffraction patterns show the formation of a pure crystalline phase with cubic (Fm3̅m) structure with partial ordering in the B-sites. The replacement of Fe by Sc leads to the increase of the cation order between the B′ and B′′ sites. As the non-magnetic Sc3+ ions replace the magnetic Fe3+ cations, the antiferromagnetic state of PbFe2∕3W1∕3O3 is turned into a ferrimagnetic state reflecting the different magnitude of the magnetic moments on the B′ and B′′ sites. The materials remain ferroelectric relaxors with increasing Sc content. Results from experiments on annealed and quenched samples show that the cooling rate after high temperature annealing controls the degree of cationic order in Pb(Fe1−xScx)2∕3W1∕3O3 and possibly also in the undoped PbFe2∕3W1∕3O3

Spin and dipole order in geometrically frustrated mixed-valence manganite Pb3Mn7O15

The structural, magnetic, and dielectric properties of Pb3Mn7O15 have been investigated using high-quality single crystals. Pb3Mn7O15 adopts a pseudo-hexagonal orthorhombic structure, with partially filled Kagom, layers connected by ribbons of edge-sharing MnO6 octahedra and intercalated Pb cations. There are 9 inequivalent sites in the structure for the Mn ions, which exist both as Mn3+ and Mn4+. Pb3Mn7O15 undergoes an antiferromagnetic transition below T-N similar to 67 K, with significant geometric frustration. Neutron powder diffraction on crushed single crystals allowed us to determine the low-temperature antiferromagnetic magnetic structure. We discuss the magnetic interaction pathways in the structure and possible interplay between the structural distortions imprinted by the lone-electron pair of Pb2+ cations and Mn3+/Mn4+ charge ordering