The system Ce–Zn–B at 800 °C

Abstract

The isothermal section for the system Ce–Zn–B has been established at 800 °C using electron microprobe analysis and X-ray powder diffraction. No ternary compounds exist and mutual solid solubilities of binary phases are negligible. In the concentration range of 10.0–10.5 at% Ce two structural modifications have been confirmed: high temperature βCe 2Zn 17 above ∼750 °C with the Th 2Zn 17 type ( R3̄ m, a=0.90916(4) nm, c=1.3286(1) nm) and low temperature αCeZn 7 (Ce 1− x Zn 5+2 x ; x∼0.33) up to 750 °C for which we attributed the TbCu 7 type ( P6 /mmm, a=0.52424(2), c=0.44274(1) nm). The crystal structure of CeZn 7 was derived from the Rietveld refinement of X-ray powder intensities. Precise data on atom site distribution and positional parameters have been furthermore provided from X-ray single crystal refinements for two compounds, for which crystal structures hitherto have only been derived from X-ray diffraction photographs: Ce 3Zn 11 ( Immm, a=0.45242(2) nm, b=0.88942(3) nm, c=1.34754(4) nm) and Ce 3Zn 22 ( I4 1 /amd; a=0.89363(2) nm, c=2.1804(5) nm).