Systematic Investigations of the Solid Solution Zr(V1-xAlx)2 Adopting the Laves Phase Structures

Abstract

Laves phases are an interesting field of research when it comes to structural chemistry and physical properties. Investigations of the ternary system Zr-V-Al showed, in contrast to the system Hf-V-Al, that no superstructures can be observed within the solid solution Zr(V1-xAlx)2. High values of x form aluminum rich phases that adopt the hexagonal MgZn2 type structure while low values of x lead to vanadium rich phases that adopt the cubic MgCu2 type. All samples were investigated by powder X-ray diffraction experiments. Single crystal studies indicated that no superstructure formation is present in the investigated samples. 27Al MAS NMR investigations confirmed these findings. For ZrAl2, quantum-chemical calculations helped with the analysis of the 27Al NMR spectrum of the binary endmember of the solid solution. Some of the prepared samples were investigated with respect to their magnetic properties. The investigated compounds show Pauli-paramagnetism, in Zr(V0.875Al0.125)2 in addition superconductivity with a critical temperature of TC = 4.17(1) K was observed. Investigations of compositions that do not belong to the Laves phase regime clearly indicate that the MgZn2 type structure is still the dominant phase. Regardless of the starting composition chosen, the hexagonal Laves phase was mostly present.

Keywords: Intermetallic phases; Laves phases; Solid-state NMR; Solid-state structures; magnetic properties.