Investigation of phase equilibria in the quaternary Ce–Mn–In–Ge system and isothermal sections of the boundary ternary systems at 800 °C

Abstract

Part of the quaternary Ce–Mn–In–Ge phase diagram has been examined through powder X-ray diffraction and energy-dispersive X-ray analysis. Two new quaternary (Ce4Mn2InGe4 and Ce2Mn2InGe2) and two ternary (Ce3Mn2Ge3 and Ce43Mn18Ge39) phases were found. The isothermal sections of the boundary ternary systems (Ce–Mn–In, Mn–In–Ge, Ce–In–Ge, and Ce–Mn–Ge) were determined at 800°C. Among these, the Ce–Mn–Ge system deserves particular attention because the phase equilibria are complex. Relative to the previously reported phase diagram evaluated at a lower temperature (400°C), three ternary phases (CeMn2Ge2, Ce2MnGe6, and CeMnGe) persist, Ce2MnGe5 does not form, and two new phases with very close composition (Ce3Mn2Ge3 and Ce43Mn18Ge39) appear at 800°C. Ce3Mn2Ge3 (orthorhombic Hf3Ni2Si3-type) has a small homogeneity range (2%) deviating from the ideal composition, whereas Ce43Mn18Ge39 (tetragonal La2+xMnGe2+y-type) has negligible homogeneity. Magnetic measurements on Ce4Mn2InGe4 suggest ferromagnetic behaviour.