The B (boron) K edges of the Be-B-bearing materials present a wide range of shapes, reflecting their different bonding types. Those bonding types affect the electrical resistivity of the materials. These properties include metallic in Be2B (12 x 10-6 Ω cm), BeB2C2 (17 x 10-4 Ω cm), and BeB2 (2 x 10-2 Ω cm); semiconducting in Be0.5B6C (3.3 Ω cm); and insulating in BeB6 and BeB8 to 12 (1 to 6 x 107 Ω cm) . Figure 2653 shows the B K edges of some B-bearing materials. The increase in the energy of the edge onset reflects the transition from metallic in Be3B to insulating in BeB6. The first sharp peak at the B K edge of Be2BO3(OH) originated from the transitions of B 1s electrons to the unoccupied p states with π* character, while the B K edge of Be3B is broad, lacking sharp features, originated from the overlap of bands due to its metallic conductivity.
Figure 2653 shows the B K edges of some B-bearing materials. The dotted vertical lines label the lowest energy onset in metallic Be2.8B (≈Be3B) and the greatest energy onset in insulating Be2BO3(OH), also see the red dots. The dotted lines have been set to the inflection points of the rising edges.
Adapted from 
The core-loss edges in EELS are a projection of the atom resolved, partial density of states (PDOS) of the conduction band. However, in certain cases core-hole effects may modulate the features near the conduction-band onset.
V. S. Neshpor and G. V. Samsonov, Inorg. Mater. 7, 45 (1971).
 Laurence A. J. Garvie, Peter R. Buseck, and Peter Rez, Characterization of Beryllium–Boron-Bearing Materials by Parallel Electron Energy-Loss Spectroscopy (PEELS), Journal of Solid State Chemistry 133, 347Ð355 (1997).