Short-Range Ordering Structure of the Cu 2 In Intermetallic Compound in the Precrystallization Temperature Range
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SHORT-RANGE ORDERING STRUCTURE OF THE Cu 2 In INTERMETALLIC COMPOUND IN THE PRECRYSTALLIZATION TEMPERATURE RANGE Z. М. Oliinyk,1 А. V. Korolyshyn,1,2 and S. І. Mudryi1
UDC 539.266+669-1
The structure of Cu 2 In melts is investigated by the X-ray diffraction method within a temperature range close to the temperature of onset of crystallization. We analyze the structural factors and functions of the radial distribution of atoms computed by the method of Fourier transforms. The results of structural investigations are compared with the literature data on the enthalpy of mixing and thermodynamic activity. It is shown that the short-range ordering structure is microinhomogeneous and has a heterocoordinated distribution of atoms. Keywords: short-range ordering, metallic melts, copper, indium.
Introduction Copper–indium alloys are of interest from the viewpoint of physics of metals because they belong to binary systems, which form intermetallic compounds, which often possess unique physical properties. Thus, a typical complex of characteristics of these alloys makes it possible to use them as special casting alloys, as solders in electronics, and also as basic components of growth of the Cu(In, Ga) Se 2 films for photovoltaic absorber. Solar cells developed on the basis of these elements have better characteristics than the corresponding cells based on crystalline silicon. The technology of formation of absorbers of this kind is based on a two-stage process: first, a CuIn film is synthesized and then reacts with selenium or sulfur [1, 2]. Moreover, alloys of this system can be used as lead-free solders as a base for these solders. It is also clear that, due to the practical use and search for new possible applications of copper–indium alloys, their comprehensive investigations under different thermodynamic conditions, including the liquid state, seem to be quite urgent.
Liquid alloys of the Cu–In system belong to alloys characterized by a trend to formation of stoichiometric and nonstoichiometric compounds in the solid state. Therefore, they exhibit an abnormal behavior of thermodynamic, structural, and kinetic characteristics as compared with the other melts. The intermetallic compounds formed in the Cu–In system have different types of structure but are characterized by chemical ordering with dense atomic distribution. Some intermediate phases appearing in this system are characterized by large ranges of homogeneity. Thus, the high-temperature γ -phase has the homogeneity range 27.7–31.3 at.% In. The alloys of this phase are solutions based on the Cu 2 In compound, which belongs to the Ni 2 In structural type [3, 4]. It is worth noting that new results refining the diagram of state of these alloys and the existing phases are published in the literature quite often [5]. 1 2
I. Franko Lviv National University, Lviv, Ukraine.
Corresponding author; e-mail: [email protected].
Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 55, No. 6, pp. 139–144, November–December, 2019. Original article submitted January
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