Phase relationships in the In-rich part of the In-Pd system

A detailed literature overview concerning the In-rich cubic phase in the In-Pd system is given, Powder X-ray diffraction, metallography including EPMA and thermal analyses of samples around the composition In70Pd30 were performed in order to evaluate the phase relationships. Our results showed that the compound In3Pd (partially filled gamma-brass structure type) hitherto reported in phase diagram compilations does not exist as an equilibrium phase. Therefore the In-rich part of the phase diagram presented here was changed replacing In3Pd by In7Pd3. The general phase relations correspond to those reported earlier for In 3Pd but the temperatures of related invariant reactions were slightly enhanced. The homogeneity range of In7Pd3 is below 0.5 at.%. The crystal structure of the binary intermetallic compound In7Pd3 was determined by single crystal X-ray diffraction using a CCD-diffractometer at room temperature. Refinements finally yielded a body centered cubic structure (space group: Im (3) over barm; Pearson symbol: cI40, Z=4) with a=9.4359(4) Angstrom. For the entire data set of 240 independent reflections residual values are R=0.0222 and R-w=0.0484. The structure is isotypic to Sn7Ir3 with In on the Sn sites and Pd on the Ir sites. Our results are in excellent agreement with a single crystal structure determination reported earlier. (C) 2002 Elsevier Science B.V. All rights reserved.