共查询到20条相似文献,搜索用时 76 毫秒
1.
Measurements of electrical resistivity after low temperature fast neutron irradiation are made for amorphous Pd80Si20 and Pd80Ni2Sl18 and then Pd80Si20 annealed at 230°C and 360°C, and the isochronal annealing curves are obtained. The resistivity increase of Pd80Si20 annealed at 360°C is about 10 times larger than that of amorphous alloys and no defined annealing stage is observed in amorphous alloys and Pd80Si20 annealed at 360°C. For amorphous Pd80Si20, about 60% of the resistivity increase by irradiation remains after annealing up to room temperature and these are discussed by the structural relaxation. 相似文献
2.
In order to determine systematic changes in the density of states with alloy composition, photoelectron spectra at hv=21.2 eV were measured for several amorphous alloys based on the well-known Pd-Si glass system. Three binary alloys with 15, 20, and 25 at. % Si, two ternaries, Pd80 Si17 Cu3 and Pd80 Si14 Cu6, and polycrystalline Pd were analyzed. Compared to Pd, both the density of states at the Fermi energy and the d-band width are reduced in the glasses. The d-bands display an overall shift of 0.4 eV over the range of alloy compositions studied. Partial agreement with recent density of states calculations was obtained. 相似文献
3.
S. Chakraborty Ch. Rajesh S. Mahamuni S. V. Ghaisas 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,64(2-3):331-337
The phenomena where the parameter like optical gap, HOMO-LUMO gap etc of a cluster will behave like a monotonic function with respect to its size is called quantum confinement effect. Here we are dealing with clusters having number of silicon atoms as 10, 16, 19, 20, 35, 54 and 78 which are representatives of different size regime clusters. For each clusters we have experimented with a number of isomers and the results we are showing are only of the stable most isomers. Then for each clusters we are capping them with oxygen atoms and calculating their optical response using DFT based calculations. We also calculate their HOMO-LUMO gap with and without oxygen atoms. The main essence of this work is mainly revolving around the variation of optical gap as well as the HOMO-LUMO gap for all the clusters with respect to their size and also whether oxygen insertion can induce any changes in quantum confinement effect. Also for Si20, Si19, Si16 and Si10 we have calculating the optical spectra with a variation of inserted oxygen on the surface of those clusters. All the calculation are performed using Vienna ab initio simulation package (VASP) and Car Parrinello molecular dynamics (CPMD) for geometry optimization. The optical spectra of the clusters are performed by real space PARSEC code and time dependent density functional theory implemented RGWBS code which takes into account the many body effects using GW and BSE equations. 相似文献
4.
The geometries, growth patterns, relative stabilities and electronic properties of small-sized Pd2Sin and Sin+2 (n = 1–11) clusters are systematically studied using the hybrid density functional theory method B3LYP. The optimised structures revealed that the lowest energy Pd2Sin clusters are not similar to those of pure Sin clusters. When n = 9, one Pd atom in Pd2Si9 completely falls into the centre of the Si outer frame, forming metal-encapsulated Si cages. On the basis of the optimised structures, the averaged binding energy, fragmentation energy, second-order energy difference and highest occupied–lowest unoccupied molecular orbital energy gap are calculated. It is found that the Pd2Si5 and Pd2Si7 clusters have stronger relative stabilities among the Pd2Sin clusters. Additionally, the stabilities of Sin+2 clusters have been reduced by the doping of Pd impurity. The natural population and natural electronic configuration analysis indicated that the Pd atoms possess negative charges for n = 1–11 and there exist the spd hybridisation in the Pd atom. Finally, the chemical hardness, chemical potential, electrostatic potential and polarisability are discussed. 相似文献
5.
6.
A. Schulte A. Eckert G. Fritsch E. Lüscher 《Zeitschrift für Physik B Condensed Matter》1983,51(3):205-208
We report on simultaneous measurements of the Hall-effect and resistivity in the metallic glasses Pd80Si20 and Ni78Si8B14. Data were taken within a temperature range of 1.7 to 300 K and in magnetic fields up to 1.1 T. Whereas the Hall constant is nearly independent of temperature in case of Pd80Si20, it changes sign at low temperatures in Ni78Si8B14. The implications of the low temperature results are discused with respect to the origin of a resistivity minimum, present in both alloys. 相似文献
7.
F. Honda A.V. Andreev V. Sechovský Y. Homma Y. Shiokawa 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(3):313-318
Single crystals of U(Ni1-xPdx)2Si2 with x = 0.05, 0.09 and 0.135 have been grown. Magnetization and electrical resistivity measurements were performed in a wide range
of temperatures and magnetic fields in order to study stability of magnetic phases in the solid solutions between UNi2Si2 and UPd2Si2 with a special emphasis on the type of ground state. In UPd2Si2 the simple AFI-type antiferromagnetic structure of U moments is observed at low temperatures. UNi2Si2 adopts the uncompensated AF structure (UAF) with the + + - stacking of U moments along the c-axis and consequently this compound exhibits a spontaneous magnetization corresponding to 1/3 of the U moment. The substitution
of Pd for Ni leads to a rapid decay of the spontaneous magnetization. The evolution of magnetization and electrical resistivity
behavior with Pd doping is tentatively attributed to the coexistence of the AF-I and UAF phases in the ground state of U(Ni0.91Pd0.09)2Si2 and U(Ni0.865Pd0.135)2Si2. In this scenario, the volume fraction of the AF-I phase rapidly grows with Pd doping on account of the UAF. At lowest temperatures
an irreversible transition to the UAF phase is observed when a sufficiently high magnetic field is applied along the c-axis.
Received 28 March 2002 / Received in final form 8 August 2002 Published online 19 December 2002
RID="a"
ID="a"e-mail: sech@mag.mff.cuni.cz 相似文献
8.
The local atomic structures of amorphous Pd80Si20 alloys and their configuration heredity in the rapid solidification are investigated by a molecular dynamics simulation with the help of cluster-type index method based on Honeycutt–Anderson bond-type index and an inversely tracking technique of atomic trajectories. Their short-range orders are found to be various Kasper clusters as well as their distorted configurations, and among which (10 2/1441 8/1551) bi-capped square Archimedean anti-prism (BSAP) clusters are dominated, e.g. Si-centred Pd10Si1 clusters. These Kasper clusters mainly exist in the form of isolated basic clusters. Few medium-range orders can be detected, especially for Si-centred Kasper clusters. Similarly to icosahedrons of Cu–Zr amorphous alloys, their sustainable configuration heredity also occurs firstly in the super-cooled liquid region, and BSAP clusters have higher onset temperature Tonset and bigger descendible fraction F than other Kasper clusters in the rapid solidification of Pd80Si20 alloys. 相似文献
9.
The amorphous alloys Pd0.8Si0.2 and Pd0.75Si0.20Ag0.05 have been studied by the time differential perturbed angular correlation method. A broad EFG distribution with a relative
width of 0.48–0.51 was sensed by the probe nuclei111Cd for both the amorphous alloys. The unique quadrupole interaction frequencies were observed after annealing above the phase
transition temperature. The observed broad distribution of the EFG implies that the crystallographic structure of the amorphous
alloys is characterized by short-range order and long-range disorder, which is in accord with the continuous random model. 相似文献
10.
P. Oelhafen M. Liard H.-J. Güntherodt K. Berresheim H.D. Polaschegg 《Solid State Communications》1979,30(10):641-644
The valence bands of glassy and pure Pd were studied by XPS and UPS. The valence band spectra of the alloys show a strongly reduced density of states at the Fermi energy EF compared to Pd. From the measured relative photoelectric cross sections for the different excitation energies we conclude that the electron states near EF of the glassy alloys have mainly d-character. This is in good agreement with recent measurements of the low-temperature specific heat, the magnetic susceptibility and the optical reflectivity. 相似文献
11.
The electrical resistivity of amorphous Fe
x
Pd80–x
Si20 alloy has been discussed in terms of extended Ziman theory. The increase in the electrical resistivity of Fe
x
Pd80–x
Si20 has been predicted due to the d-resonance scattering of the conduction electrons by Fe-atoms.Dedicated to Academician Vladimír Hajko on the occasion of his 65th birthday. 相似文献
12.
13.
Mahesh Kumar Mohana K. RajpalkeBasanta Roul Thirumaleshwara N. BhatNeeraj Sinha A.T. KalghatgiS.B. Krupanidhi 《Applied Surface Science》2011,257(6):2107-2110
Ultra thin films of pure silicon nitride were grown on a Si (1 1 1) surface by exposing the surface to radio-frequency (RF) nitrogen plasma with a high content of nitrogen atoms. The effect of annealing of silicon nitride surface was investigated with core-level photoelectron spectroscopy. The Si 2p photoelectron spectra reveals a characteristic series of components for the Si species, not only in stoichiometric Si3N4 (Si4+) but also in the intermediate nitridation states with one (Si1+) or three (Si3+) nitrogen nearest neighbors. The Si 2p core-level shifts for the Si1+, Si3+, and Si4+ components are determined to be 0.64, 2.20, and 3.05 eV, respectively. In annealed sample it has been observed that the Si4+ component in the Si 2p spectra is significantly improved, which clearly indicates the crystalline nature of silicon nitride. The high resolution X-ray diffraction (HRXRD), scanning electron microscopy (SEM) and photoluminescence (PL) studies showed a significant improvement of the crystalline qualities and enhancement of the optical properties of GaN grown on the stoichiometric Si3N4 by molecular beam epitaxy (MBE). 相似文献
14.
S. G. Ovchinnikov S. N. Varnakov S. A. Lyashchenko I. A. Tarasov I. A. Yakovlev E. A. Popov S. M. Zharkov D. A. Velikanov A. S. Tarasov V. S. Zhandun N. G. Zamkova 《Physics of the Solid State》2016,58(11):2277-2281
Ferromagnetic single-crystal epitaxial Fe3Si films and polycrystalline Fe5Si3 films are obtained on Si substrates by molecular-beam epitaxy with in situ control of the structure, optical, and magnetic properties. The results of the structural, magnetic, and optical measurements are discussed. The experimental data are compared to the results of the microscopic calculation of the spin-polarized structure, the permittivity, and the optical conductivity spectra. 相似文献
15.
Y.H. Kwon C.J. Park T.W. Kim J.Y. Lee B.O. Kim Yong-Hoon Cho 《Solid State Communications》2006,140(1):14-17
The optical properties and the deep levels in bulk Si1−xMnx formed by using an implantation and annealing method were investigated. Transmission electron microscopy, X-ray diffraction, and Hall-effect measurements showed that the annealed bulk Si1−xMnx samples were p-type crystalline semiconductors. The photoluminescence spectra for the annealed bulk Si1−xMnx material showed luminescence peaks corresponding to excitons bound to neutral acceptors and related to dislocations due to the existence of Mn impurities. Deep-level transient spectroscopy results for the annealed bulk Si1−xMnx showed deep levels related to the interstitial and substitutial sites of the Mn+ ions. These results can help improve understanding of the optical properties and the deep levels in annealed bulk Si1−xMnx material. 相似文献
16.
V. O. Vas’kovskii P. A. Savin S. O. Volchkov V. N. Lepalovskii D. A. Bukreev A. A. Buchkevich 《Technical Physics》2013,58(1):105-110
The magnetization reversal and magnetic impedance (MI) of films and film elements based on Fe19Ni81 and Fe72.5Cu1.1Nb1.9Mo1.5Si14.2B8.7 alloys with a varied thickness, heat-treatment temperature, and the number of thin Cu interlayers are studied. The dependences of the coercive force and the magnitude of MI on these parameters are found. Layered structuring is shown to be an effective method for improving the functional characteristics of MI elements. In elements containing nanocrystalline Fe19Ni81 layers, this is related to the restructuring of a magnetic structure; in elements containing amorphous Fe72.5Cu1.1Nb1.9Mo1.5Si14.2B8.7 layers, this improvement is likely to be caused by a decrease in the effective electrical resistivity. 相似文献
17.
I. Abbati L. Braicovich B.De Michelis U.Del Pennino S. Valeri 《Solid State Communications》1980,35(12):917-920
Photoemission and Auger results are given for Si(III)Pd and Si(III)Pt interfaces prepared by depositing 10 ml metal onto cleaved Si(III). Thermal cycling between room temperature and liquid nitrogen temperature originates a reversible effect in the spectra due to metal concentration increase in and decrease in . The results are discussed in connection with open problems on Si d-metal interfaces. 相似文献
18.
G. Fritsch W. Dyckhoff J. Willer E. Lüscher 《Zeitschrift für Physik B Condensed Matter》1983,53(3):191-196
Measurements of the thermopower for amorphous alloys are reported in the temperature range 77K to 320K. The alloys examined are Cu50Ti50, Pd80Si20, Pd30Zr70 and Cu40Zr60. The data are compared with values of similar systems, as far as available. In addition we analyse the temperature coefficient of the thermopower, applying a model, based on the Ziman formulation of the transport properties. 相似文献
19.
Spectroscopic ellipsometric characterization of TiAlN/TiAlON/Si3N4 tandem absorber for solar selective applications 总被引:1,自引:0,他引:1
Sputter deposited TiAlN/TiAlON/Si3N4 tandem absorber has been characterized by spectroscopic ellipsometry in the wavelength range of 450-1200 nm. Each layer of the tandem absorber viz., TiAlN, TiAlON and Si3N4 has been deposited separately on copper substrate (Cu) and ellipsometric measurements have been carried out on each of these layers. The measured ellipsometric spectra were fitted with theoretically simulated spectra and the sample structure and wavelength dispersion of optical constants of each layers have been determined. The ellipsometric measurements have also been carried out on the three-layer tandem absorber deposited on Cu substrate. By analyzing the ellipsometric data, depth profiling of the tandem absorber has been carried out using the derived optical constants of the individual layers. 相似文献