Single phase γ′-Fe4N type (Fe1−xNix)4N compounds (0≤x≤0.6) have been synthesized by heating iron-nickel oxalates under a mixture stream of NH3 and H2. The compounds were investigated by x-ray diffraction and Mössbauer spectroscopy. The results confirm that the lattice constants decrease with increasing content of nickel. Compared with the same compositional Fe1−xNix alloys, the average expansion of the unit cell (δV/V) is 16.7% for γ-Fe-Ni alloys. The Mössbauer study shows that the substitution of nickel atoms for iron atoms has a tendency to locate at the corner sites. When x=0.5, all of the corner sites are completely occupied by nickel atoms.

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Ultrafine bismuth nanowire arrays have been fabricated by electrodeposition into nanoporous anodic aluminum templates in a composite electrolyte solution, in which the diameter of nanowire as low as 3 nm can be obtained. The micrographs and crystal structures of Bi nanowires are studied by transmission electron microscopy (TEM), selected-area electron diffraction (SAED), and X-ray diffraction (XRD). It is found that each nanowire is essentially a single crystal and has a different orientation in an array. The optical properties of the Bi nanowire arrays are studied by UV-VIS spectra. The experimental results exhibit blue-shifted phenomena with decreasing wire diameter, which is qualitatively consistent with the effective medium theory. © 2000 Elsevier Science S.A. All rights reserved.Keywords: Quantum-wires arrays; Aluminum oxide; Bismuth nanowire www.elsevier.com/locate/mseb Semimetallic bismuth is a material exhibiting interesting magnetoresistance (MR) characteristics and finitesize effects, whose electronic properties are fundamentally different from those of common metals due to the complex and highly anisotropic Fermi surface [1][2][3][4][5][6][7]. Especially, ultrafine bismuth nanowires arrays are considered a good candidate to study quantum confinement effect, which is desirable for wide-field sensing [8] [9,10,12,13]. However, the attribution of pores of polycarbonate membrane is not uniform, which can not be used to fabricate the high quality arrays of Bi nanowires. The pressure injection method or a vaporphrase technique is difficult to fabricate the pore diameter of bismuth nanowires below 10 nm. And this method is highly costly, and complex in operation. If the fabrication by electrodeposition into nanoporous anodic aluminum oxide (AAO) can be carried out, the shorts can been avoided. To the best of the authors' knowledge, the arrays of Bi nanowires were not prepared by electrodeposition into nanoporous AAO films. The possible reason is that the bismuthal salt is very easy to hydrolyze. When the solution pH is controlled under 0.9 or lower, the nanoporous AAO templates are dissolved in solution.When anodized in an acidic electrolyte, aluminum forms a porous oxide with very uniform and parallel pores open at one end and sealed at the other [15][16][17][18]. Its structure is described as a closed-packed array of columnar cells, each containing a central pore of which the side and interval can be controlled by changing the forming conditions. In recent years, there has been interest in this material as a medium for creating uniform nanostructures since its pores can function as 'nanotemplates' in which small metal and semiconductor particles can be electrochemically deposited [15][16][17][18][19][20][21][22].Here, the Bi quantum-wire arrays were electrodeposited in nanoporous AAO membranes by a novel deposition electrolyte solution which was prepared. The technique successfully carried out the fabrication of Bi * Corresponding author.0921-5107/00/$ -see front matter © 2000 Elsevier Science S.A....

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Single phase y'-Fe&-type (Fel_,Ni,)fi compounds and Fel-,Ni, (0 5 x 5 0.6) alloys are synthesized and studied by X-ray diffraction and Mossbauer spectroscopy. The structure changes from b.c.c. to f.c.c. when Fel_,Ni, (x 5 0.25) alloys are nitrided to (Fel-,Ni,)4N. The lattice expansion Aa/a is 5.3% for f.c.c. Fel-,Ni, alloys (x > 0.25) on nitrogenation. The observed decrease in the average iron hyperfine fields with nitrogenation, amounting to 8 to 14 T, is explained by the volume expansion and the chemical bond effects. The chemical bond effect is about three times larger than the volume effect.The increase in the average isomer shift after nitriding is mainly due to the effect of chemical bonds, which changes the electronic configuration of iron.