Boron-induced phase transformation of ternary cerium boron silicides

Abstract

Samples of the alloys CeSi2–хBх (x = 0, 0.1, 0.2, 0.4, and 0.5) were prepared and their crystal structures, electrical and magnetic properties were determined. Depending on the amount of boron, x, the phases CeSi2–хBх crystallize in the α-ThSi2 structure type (x = 0, 0.1), or in the α-GdSi2 structure type (x = 0.2, 0.4). Interestingly, as determined by means of X-ray single crystal diffraction crystallizes, CeSi1·5B0.5 crystallizes in the AlB2 structure type (space group P6/mmm, a = 3.9922(2), c = 4.3053(4) Å, 191 reflections with Io ≥ 2σ(Io), R1 = 0.019, wR2 = 0.042). Measurements of the electrical and magnetic properties indicate that phases CeSi2-xBx (x = 0, 0.1, 0.2, 0.4, 0.5) are metallic in character and that phases with B substitution x ≥ 0.2 exhibit correlated magnetic behavior, typically below ∼15 K. Density functional theory calculations were performed to elucidate the change of electronic and physical properties upon boron substitution.