Abstract
The low temperature (1–20K) heat capacity results of lutetium containing up to 15.5 at.%H in solid solution were measured. In alloys containing between 0.1 and <3.0 at.%H a low temperature anomaly was observed in the C/T vs. T
2 plots below 2.5K, but alloys containing 3.0 or more at.% H were linear down to the lowest temperature measured. The electronic specific heat constant, γ, initially increased by ∼35% when 1.5 at.% H was added, and then γ decreased at higher hydrogen concentrations. The Debye temperature, θ
D, may also show a similar variation. These anomalous behaviors are thought to be due to hydrogen tunneling.