Specific-heat anomaly during vitrification of hydridedFe2Er single crystals

A solid-state amorphization reaction is observed on hydrided, initially single-crystalline, ${\mathrm{Fe}}_2$Er powder samples (${\mathrm{Fe}}_2$ ${\mathrm{ErH}}_{\mathit{x}}$, 3.0<x<3.4). Specific-heat measurements at constant concentration (x=3.4) show pronounced premelting effects exhibiting a lambda-type transition at ${\mathit{T}}_{\mathit{c}}$=475.6 K and a logarithmic temperature dependence. This typical feature of an instability underlying the ‘‘melting’’ transition has been predicted if the vitrification occurs in the vicinity of the triple point between supersaturated crystal, undercooled liquid, and glass.