45 research outputs found
As-doping effect on magnetic, optical and transport properties of Zn 0.9Co0.1O diluted magnetic semiconductor
We report on the structural, magnetic, optical and transport properties of As-doped Zn0.9Co0.1O thin films. X-ray diffraction indicates highly (0 0 0 1) textured samples free of secondary phases. Transmission UV-Vis spectroscopy shows that Co is in the +2 oxidation state and substitute for the Zn2+ ions of the ZnO matrix. ZnCoO was doped with 0.5% As which lead to n-type doping. Before and after As-implantation, the films remain ferromagnetic up to 350 K and the magnetization is unchanged. Surprisingly, there is no real influence of the doping process on the exchange interaction mediated by itinerant carriers between magnetic ions. © 2006 Elsevier B.V. All rights reserved
Structure and Emissive Properties of Heterobimetallic LnâAu Coordination Polymers: Role of Tb and Eu in Non-aurophilic [ n
Mechanism of Action Studies of Lomaiviticin A and the Monomeric Lomaiviticin Aglycon. Selective and Potent Activity Toward DNA Double-Strand Break Repair-Deficient Cell Lines
Design, Synthesis, and StructureâActivity Relationships of Pyridoquinazolinecarboxamides as RNA Polymerase I Inhibitors
Hospitality Leadership Course Design and Delivery: A BlendedâExperiential Learning Model
Effectiveness of Technology Enhancement in Blended Learning: An Instrumental Perspective
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Mixed Copper, Silver, and Gold Cyanides, (MxM '(1-x))CN: Tailoring Chain Structures To Influence Physical Properties
Binary mixed-metal variants of the one-dimensional MCN compounds (M = Cu, Ag, and Au) have been prepared and characterized using powder X-ray diffraction, vibrational spectroscopy, and total neutron diffraction. A solid solution with the AgCN structure exists in the (CuxAg1âx)CN system over the range (0 †x †1). Line phases with compositions (Cu1/2Au1/2)CN, (Cu7/12Au5/12)CN, (Cu2/3Au1/3)CN, and (Ag1/2Au1/2)CN, all of which have the AuCN structure, are found in the gold-containing systems. Infrared and Raman spectroscopies show that complete ordering of the type [MâCâĄNâMâČâNâĄCâ]n occurs only in (Cu1/2Au1/2)CN and (Ag1/2Au1/2)CN. The sense of the cyanide bonding was determined by total neutron diffraction to be [AgâNCâAuâCNâ]n in (Ag1/2Au1/2)CN and [CuâNCâAuâCNâ]n in (Cu1/2Au1/2)CN. In contrast, in (Cu0.50Ag0.50)CN, metal ordering is incomplete, and strict alternation of metals does not occur. However, there is a distinct preference (85%) for the N end of the cyanide ligand to be bonded to copper and for AgâCNâCu links to predominate. Contrary to expectation, aurophilic bonding does not appear to be the controlling factor which leads to (Cu1/2Au1/2)CN and (Ag1/2Au1/2)CN adopting the AuCN structure. The diffuse reflectance, photoluminescence, and 1-D negative thermal expansion (NTE) behaviors of all three systems are reported and compared with those of the parent cyanide compounds. The photophysical properties are strongly influenced both by the composition of the individual chains and by how such chains pack together. The NTE behavior is also controlled by structure type: the gold-containing mixed-metal cyanides with the AuCN structure show the smallest contraction along the chain length on heating