THE INTERACTION OF THE COMPONENTS IN THE R2T2In1-xGax (R = La, Ce; T = Ni, Cu) SYSTEMS

This work is devoted to the study of R2T2In1-xGax (R = La, Ce; T = Ni, Cu) systems at 870 K, namely the solubility of the fourth component in compounds with the composition 2:2:1 and structural characteristics of the solid solutions. Samples for the investigation were synthesized by arc-melting of metals (purities better than 0.998) with subsequent annealing at 870 K for one month in the electric muffle furnace SNOL with automatic temperature control. The phase compositions of the alloys were characterized by means of X-ray powder diffraction (DRON-2.0M, Fe Kα-radiation, HZG 4a, Cu Kα-radiation and Guinier camera Fujifilm BAS–1800, Cu Kα-radiation) and energy dispersive X-ray analysis (scanning electron microscope Leica 420i). According to the results of experimental studies, the solubility of Gallium in the La2Ni2In and Ce2Ni2In compounds is not more than 4 at. %. The unit cell parameters of the solid solutions with Mo2FeB2-type structure are: a = 0.7627–0.7609(4), c = 0.3905–0.3898(3) nm, V = 0.2272–0.2257(1) nm3 for La2Ni2In1-0.8Ga0-0.2 and a = 0.7530–0.7503(3), c = 0.3722–0.3718(2) nm, V = 0.2110–0.2093(1) nm3 for Ce2Ni2In1-0.8Ga0-0.2. Significant solubility of indium in ternary gallides with Mo2NiB2-type structure under the conditions of the study was not detected. During the investigation of the components interaction in the R2Cu2In1-xGax (R = La, Ce) systems less 7 at.% of Gallium solubility in the ternary La2Cu2In and Ce2Cu2In compounds at 870 K was detected. The solid solutions with the Mo2FeB2-type structure can be described by formulas: La2Cu2In1-0.65Ga0-0.35 (a = 0.7737–0.7709(4), c = 0.3924–0.3936(3) nm, V = 0.2349–0.2339(1) nm3) and Ce2Cu2In1-0.65Ga0-0.35 (a = 0.7797–0.7774(3), c = 0.3991–0.3999(3) nm, V = 0.2426–0.2417(1) nm3). The peculiarities of the interaction of components in the studied and related systems are briefly discussed.