Electronic Properties and the Lattice Instability of Laves-Phase ZrV2

Pure, perfect, single-crystal Zr${\mathrm{V}}_2$ does not undergo a structural phase transformation but all other sample modifications, including twinned single crystal, do transform (∼100 K) from the cubic to a rhombohedral phase. All samples exhibit, in addition, an electronic instability (also ∼100 K). An anomaly in the ultrasonic velocity occurs at higher temperatures (∼150-180 K) for pure polycrystalline Zr${\mathrm{V}}_2$ samples.