DOI: https://doi.org/10.30970/jps.03.463
THE ATOMIC ORDERING OF Pb–Te MOLTEN ALLOYS AT NEAREUTECTIC COMPOSITION
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Journal of Physical Studies 3(4), 463–467 (1999)
DOI: https://doi.org/10.30970/jps.03.463 THE ATOMIC ORDERING OF Pb–Te MOLTEN ALLOYS AT NEAREUTECTIC COMPOSITION |
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N. Klym, A. Korolyshyn, S. Mudry
Ivan Franko National University of Lviv,
Physics of Metals Department
8 Kyrylo i Mefodii Str., Lviv, UA-79005, Ukraine
The short–range order of liquid $\mbox{Pb}_x\mbox{Te}_{1-x}$ alloys of different compositions (30, 35, 40, 46, 48, 50, 52, 54 at.\%Te) has been investigated by means of X–ray diffraction method at the temperatures of about 5~K above the liquidus curve of phase diagram. It was found that atomic arrangement in molten chemical compound PbTe is determined by chemical ordering. When Pb atoms are added to equatomic alloy the short–range order becomes more microinhomogeneous and main structural units are both selfassociated atoms of Pb and chemical complexes of PbTe. The ordered atomic arrangement which is observed in liquid PbTe alloys persists when the atoms of Te are added to the equatomic chemical compound.
A tendency towards the formation of a chemically ordered short–range order was confirmed by the estimation of configuration entropy of mixing which was calculated with the use of experimental structural data. The calculated value is negative for the equiatomic alloy and shows that the topological short–range order in this alloy is more ordered than in other alloys of this system. A model of associates was also used to describe the atomic distribution of $\mbox{Pb}_x\mbox{Te}_{1-x}$ alloys. The structure factors estimated with the use of this model are in accordance with the experimental structure factors.