β-Boron and a1b12 as quasi-amorphous semiconductors and thermoelectrical materials

β-Rhombohedral Boron: At the Crossroads of the Chemistry of Boron and the Physics of Frustration

“…The Arrhenius plot of the conductivity of β-boron is known to show two kinks, T ∼ 200 and 550 K, ,,,, (related to anomalous behaviors discussed later), and the slope of ln σ(1/ T ) significantly increases at each kink. It is also known that the number of electronic states within the band gap increases significantly above T ∼ 200 K. , Therefore, it is natural to expect that the electronic contribution to the specific heat will also increase at higher temperatures, much more so than in a normal semiconductor.…”