Yazar "Demir L." seçeneğine göre listele

Listeleniyor 1 - 4 / 4
  • Küçük Resim Yok
    Öğe
    Delocalization and charge transfer studies of PERMENDUR49, KOVAR and Ti50Co50 alloys from relative K X-ray intensity ratios
    (Elsevier Ltd, 2017) Uğurlu M.; Alım B.; Han İ.; Demir L.
    K?-to-K? X-ray intensity ratios of Fe, Ni, Co, Ti, V in pure form and PERMENDUR49 (Fe49Co49V2), KOVAR (Fe54Ni29Co17) and Ti50Co50 alloys were calculated in order to determine valence-electron structure of the samples. The obtained experimental K?-to-K? X-ray intensity ratios were found to be 0.1252 ± 0.0025, 0.1256 ± 0.0027, 0.1298 ± 0.0026, 0.1327 ± 0.0028, 0.1346 ± 0.0027 for pure Ti, V, Fe, Co and Ni, respectively. These values of present pure metals have increased with the increment in atomic number of these pure metals. Also, although the obtained these values for metal atoms in PERMENDUR49, Ti50Co50 and for Fe, Ni metal atoms in KOVAR approximately compatible with respect to results same pure metals, the obtained experimental K?-to-K? X-ray intensity ratios for Co in KOVAR are significantly different from the appropriate values for pure Co metal. Then, the valence-electron populations of these alloys were calculated in order to answer as to why the characteristic properties of the studied alloys are distinct from each other. The valence-electron structures of these metals in pure form and alloys were determined by comparison of the calculated K?-to-K? X-ray intensity ratios with the results of multi-configurations Dirac-Fock (MCDF) calculations to understand the charge-transfer and/or delocalization phenomena of these alloys. The experimental n3d values were found to be 3.2694, 4.7905, 7.7941, 7.9618, 8.500 for pure Ti, V, Fe, Co and Ni, respectively. The calculated 3d and 4s, 4p electron population values for Ti, V and Co in pure form have shown very little deviation from the appropriate values of Ti in Ti50Co50 and Co, V in PERMENDUR49. Also, the deviation for these values is greater for Fe, Ni, in KOVAR, Co in Ti50Co50, Fe in PERMENDUR49 with respect to the corresponding values of pure metals and the largest deviation for these values is observed for Co metal atoms in KOVAR alloy. We have also calculated the weighted average numbers of 3d and 4s, 4p electrons per one atom as well as the superposition of 3d and 4s, 4p electrons, as obtained from pure metal values. While the obtained superposition 3d electron numbers of present alloys exhibit a decreasing tendency as S3d(Ti50Co50) < S3d(PERMENDUR49) < S3d(KOVAR), the obtained weighted average 3d electron numbers of present alloys has opposite tendency (A3d(KOVAR) < A3d(PERMENDUR49) < A3d(Ti50Co50)). The analysis show that valance-electron population of elements in these alloys indicated differences with respect to the pure metal and each other. These differences can be related to type of alloy elements, concentration of alloy elements, charge transfer and/or delocalization phenomena between of individual metal atoms in alloys. Also, the obtained results show that there are alloying effect on valence-electron population due to charge transfer and/or delocalization phenomena. © 2016 Elsevier B.V.
  • Küçük Resim Yok
    Öğe
    Determination of K shell XRF parameters and K to L shell vacancy transfer probabilities of ferromagnetic 3d transition metals
    (American Institute of Physics Inc., 2017) Allm B.; U?urlu M.; Han I.; Demir L.
    In this study, K shell X-ray fluorescence cross-sections (?K?, ?K? and ?K), K shell fluorescence yields (?K) and K to L shell vacancy transfer probabilities (?KL) of ferromagnetic 3d transition metals (Fe, Co, Ni) were investigated to understand how the relationship between ferromagnetism and these values changes with atomic number by using energy dispersive X-ray fluorescence (EDXRF) technique. The all obtained experimental and theoretical results were comparatively given as a function of the atomic number. It was clearly observed that all of the investigated parameters depend on the atomic number and the ferromagnetism state of the atom. © 2017 Author(s).
  • Küçük Resim Yok
    Öğe
    Effect of external magnetic field on the K?/K? X-ray intensity ratios of Ti x Ni 1-x alloys excited by 59.54 and 22.69keV photons
    (Elsevier Ltd, 2016) Perişanoğlu U.; Alım B.; Uğurlu M.; Demir L.
    The effects of external magnetic field and exciting photon energies on the K?/K? X-ray intensity ratios of various alloy compositions of Ti-Ni transition metal alloys have been investigated in this work using X-ray fluorescence spectroscopy. The spectrum of characteristic K-X-ray photons from pure Ti, pure Ni and Ti x Ni 1-x (x=0.30; 0.40; 0.50; 0.60; 0.70) alloys were detected with a high resolution Si (Li) solid-state detector. Firstly, K?/K? X-ray intensity ratios of pure Ti, pure Ni and Ti x Ni 1-x alloys were measured following excitation by 59.54 keV ?-rays from a 200 mCi 241 Am radioactive point source without any magnetic field and under 0.5 and 1 T external magnetic fields, separately. Later, the same measurements were repeated under the same experimental conditions for 22.69 keV X-rays from a 370 MBq 1 0 9 Cd radioactive point source. The results obtained for K?/K? X-ray intensity ratios of pure Ti, pure Ni, Ti and Ni in various Ti-Ni alloys were evaluated in terms of both external magnetic field effect and exciting photon energy effect. When the results obtained for both exciting photon energies are evaluated in terms of changing of K?/K? X-ray intensity ratios depending on the alloy composition, the tendency of these changes are observed to be similar. Also, K?/K? X-ray intensity ratios for all samples examined have changed with increasing external magnetic field. Therefore, the results obtained have shown that K?/K? X-ray intensity ratios of Ti and Ni in Ti x Ni 1?x alloys are connected with the external magnetic field. The present study makes it possible to perform reliable interpretation of experimental K?/K? X-ray intensity ratios for Ti, Ni and Ti x Ni 1?x alloys and can also provide quantitative information about the changes of the K?/K? X-ray intensity ratios of these metals with alloy composition. © 2016 Elsevier Ltd
  • Küçük Resim Yok
    Öğe
    Effect of external magnetic field on valence-electron structures of Fe and Ni in Invar, Permalloy and the other Fe-Ni alloys by using K?-to-K? X-ray intensity ratios
    (Elsevier Ltd, 2016) Alim B.; Han I.; Demir L.
    The effect of external magnetic field on the valence-electron structures of Fe and Ni in various Fe-Ni alloy compositions was investigated by using X-ray fluorescence spectroscopy. K?-to-K? X-rayin-tensity ratios of Fe and Ni in Invar(Fe 0.64 Ni 0.36 ), Permalloy(Fe 0.20 Ni 0.80 ) and Fe N - i x 1x Firstly,(x=0, 0.40, 0.52, 0.55, 0.61, and 1) alloys were measured without any magnetic field and under 0.5 and 1 T external magnetic fields, separately. Later, the valence-electron structures of Fe and Ni in both pure form and alloys were obtained by comparison of measured X-ray intensity ratios with the results of multi-configurations Dirac-Fock (MCDF) calculations. The results obtained for valence-electron structures of Fe and Ni in various Fe-Ni alloys were evaluated in terms of magnetic field effect, delocalization and/or charge transfer phenomena. The results have shown that valence electron structure of Fe and Ni in Fe-Ni alloys are dependent on both external magnetic field and concentration of alloy elements. © 2016 Elsevier Ltd.