Structural, electronic, and magnetic properties of Fe-Y alloys

Nanoglasses: A New Kind of Noncrystalline Material and the Way to an Age of New Technologies?

Today's technologies are primarily based on crystalline materials (metals, semiconductors, etc.), as their properties can be controlled by varying their chemical and/or defect microstructures. This is not possible in today's glasses. The new features of nanoglasses--consisting of nanometer-sized glassy regions connected by interfaces--are that their properties may be controlled by varying their chemical and/or defect microstructures, and that their interfaces have a new kind of non-crystalline structure. By utilizing these new features, an age of new technologies based on non-crystalline materials (a "glass age") may be initiated.

Synthesis of an Fe rich amorphous structure with a catalytic effect to rapidly decolorize Azo dye at room temperature

In this article, an amorphous Fe rich amorphous structure designed based on a competitive atomic cluster model was synthesized and characterized successfully. The constituent zero-valent iron (ZVI) has excellent activity and efficiency for decolorization of Orange G (OG) solution at room temperature. The decolorization is characterized by UV-vis spectrum and pseudo-first-order kinetics. The X-ray Micro fluorescence spectrometer, Inductively Coupled Plasma Optical Emission Spectrometry, and Scanning Electron Microscope were employed to trace the ZVI. The consumption of ZVI destabilizes the local atomic arrangement and yields the phase separation of Fe at the surface and responds to the high activity and the catalysis for decolorization. This observation is in accordance with the change of k1 0.011 min(-1) to k2 0.047 min(-1), which is supported by the cyclic decolorization test. This work provides a new strategy to design multifunctional metal materials and indicates their brilliant future in practical applications.

Correlation between magnetic properties and the electronic structures of soft magnetic ternary Fe(78-x)Y(x)B(22) (x = 4-9) bulk metallic glasses

Fe and Y K-edge extended x-ray absorption fine structure, Fe(Y) L(3,2)-edge (L(3)-edge) x-ray absorption near-edge structure (XANES) and valence-band photoemission spectroscopy (VB-PES) measurements have been carried out to study soft magnetic ternary Fe(78-x)Y(x)B(22) bulk metallic glasses (BMGs). The combined XANES and VB-PES results do not show broadening of the Fe 3d band to support the previous interpretation of the reduction of the magnetic moment in BMGs by Y-induced decrease of exchange splitting of Fe 3d orbitals. Instead, the density of delocalized/itinerant Fe 3d states in the vicinity of the Fermi level is found to be reduced by Y substitution, which reduces the strength of itinerant-states-mediated ferromagnetic coupling between local spins on the Fe ions and the total magnetic moment of the Fe-based BMGs.

First-principles calculations of the structural stability and magnetic property of the metastable phases in the equilibrium immiscible Co-Au system

To reveal the energetic sequence of the alloy phases in the Co-Au system, the lattice constants, cohesive energies, and bulk modulus of the fcc Au, hcp Co, the B1, B2, and L1(0) structured CoAu phases, and the D0(3), L1(2), and D0(19) structured Co(3)Au and CoAu(3) phases, respectively, are acquired by first-principles calculations within the generalized-gradient approximation (GGA) as well as within the local density approximation (LDA). In addition, the magnetic moment of the Co atom in the studied phases are also calculated. To further examine the structural stability, the elastic constants of the studied phases are calculated and the results suggest that the fcc-type structures could be elastically stable at Co/Au = 1:3, 1:1, and 3:1, whereas the hcp-type structures could be stable at Co/Au = 1:3 and 3:1. Moreover, the spatial valence charge density (SVCD) and spin density of the studied phases are also calculated to clarify the physical origin of the structural stability. It turns out that, in the relatively stable phases, the high SVCDs mostly distribute between the similar atoms, thus forming the attractive covalent bonding to stabilize the respective structures, and that the spin density may also play an important role in influencing the stability of the ferromagnetic metastable phases.