Physikalisches Institut, Johann Wolfgang Goethe-Universität, 60054 Frankfurt am Main, Germany

Elements of the Phase Diagram of YbInCu₄

To clearify how the valence transition temperature of YbInCu₄ is connected with the composition of the grown crystals, we investigated the phase diagram. Since elements of the liquidus curve of the system Yb-In-Cu were already known we focused on the solidus curve in the surrounding of the valence changing YbInCu₄. Bridgman-technique for crystal growth was used. The composition of the solidified crystals was determined by means of wavelength-dispersive X-ray analysis. The valence transition temperature is measured via the lattice constant by low temperature X-ray diffraction. Results are, that the assumed exchange of Yb and In, which is indicated in the formula Yb_xIn_2-xCu₄ seems to be not correct. Not the quasi-binary section for constant Copper content should be used, but one for constant Ytterbium content. Starting compositions with an excess of Ytterbium lead to the substitution of Indium by Copper. The valence transition temperature of these crystals is shifted from 40K to 70K.

Keywords: YbInCu₄, valence transition, phase diagram, Bridgman-method

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