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 diagr am. Since elements of the liquidus curve of the system Yb-In-Cu were alread y known we focused on the solidus curve in the surrounding of the valence c hanging YbInCu4. Bridgman-technique for crystal growth was used. The compos ition of the solidified crystals was determined by means of wavelength-disp ersive X-ray analysis. The valence transition temperature is measured via t he lattice constant by low temperature X-ray diffraction. Results are, that the assumed exchange of Yb and in, which is indicated in the formula YbxIn2-xCu4 seems to be not correct. Not the quasi-binary secti on for constant Copper content should be used, but one for constant Ytterbi um content. Starting compositions with an excess of Ytterbium lead to the s ubstitution of Indium by Copper. The valence transition temperature of thes e crystals is shifted from 40K to 70K.