Correlation Between Resistivity Characteristics and Electronic Structure Parameters of the Ni-Pd-P Amorphous Alloys
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CORRELATION BETWEEN RESISTIVITY CHARACTERISTICS AND ELECTRONIC STRUCTURE PARAMETERS OF THE Ni-Pd-P AMORPHOUS ALLOYS Mykola Babich, Olesya Nakonechna, Mykhailo Semen’ko, Mykola Zakharenko, Gennagy Yeremenko and Alain R. Yavari* Taras Shevchenko National Kiev university, Department of Physics, Kyiv, Ukraine * LTPCM-CNRS, INPG, St.-Martin-d-Heres, France ABSTRACT The temperature dependencies of resistivity of the Ni-Pd-P-based amorphous alloys (P content was varied from 14 to 23 at. %) have been measured in a wide temperature range using the standard four-probe method. The temperature coefficients of resistivity (TCR) have been calculated. TCR value is decreased with P content increasing and becomes negative for Ni46Pd31P23 alloy. On the other hand, TCR value is increased with Pd content increasing while P content is not changed. Such behavior could be attributed to the electronic transfer effect from Ni to Pd and from P to Ni. These lead to the Fermi level shift to d-band edge and to the increasing influence of the Mott’s localized state. The peculiarities caused by structural relaxation processes have been observed at the temperature range of 550 – 620 K. The relaxation process was shown to consist at least of two stages. The kinetics of the crystallization process has been analyzed using the Kissinger method. INTRODUCTION Amorphous metallic alloys are of interest in studying physical properties of disordered systems. It is known that the localized states are formed at the edge of energy band in such systems [1]. The contribution of these states to such physical properties as electron conductivity, magnetic susceptibility and thermopower depends on the Fermi level position with relation to dband edge. From this standpoint we can consider the Ni-Pd-P alloys as model ones because the Fermi level of the Ni-P alloys is placed at higher part of d-band but d-stated of Pd are placed deeper than those of Ni. Thus, it is possible to change the Fermi level position by the variation of transition metal (TM) components ratio. Another reason, which can change the value of electrons in TM d-band of amorphous alloy, is the presence of P atoms. This metalloid, as it is known, appears as an electron’s donor in such systems [2]. So, the Fermi level shifting to the maximum of d-band must accompany the increasing of P content. Thus, we can control the Fermi level position with the changing of Ni-Pd-P content. Consequently, we can define the correlation between the peculiarities of the electronic structure and physical properties of amorphous alloy. Here, we present the results of resistivity measurements of the Ni-Pd-P amorphous alloys and analysis of the correlation between resistivity characteristics and the electronic structure peculiarities. EXPERIMENTAL PROCEDURE Ni-Pd-P-based metallic glasses in a form of ribbons from 2 to 30 mm wide were obtained by melt quenching technique.
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The electrical resistivity was investigated in the temperature range 300-900 K under argon atmosphere using four-probe method using a computer-con
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