Electrical Resistivity of Materials studied by EELS
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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) [1]. 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.

B K edges of some B-bearing materials

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 [2]

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.

 

 

[1] V. S. Neshpor and G. V. Samsonov, Inorg. Mater. 7, 45 (1971).
[2] 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).

 

 

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