Raman spectroscopy of boron carbides and related boron‐containing materials

Raman spectra of crystalline boron, boron carbide, boron arsenide (B12As2), and boron phosphide (B12P2) are reported. The spectra are compared with other boron‐containing materials containing the boron icosahedron as a structural unit. The spectra exhibit similar features some of which correlate with the structure of the icosahedral units of the crystals. The highest Raman lines appear to be especially sensitive to the B‐B distance in the polar triangle of the icosahedron. Such Raman structural markers are potentially useful in efforts to tailor electronic properties of these high temperature semiconductors and thermoelectrics.Raman spectroscopy is also useful in characterizing methods of preparation of boron‐based materials. For example, inclusions of carbonaceous material in the boron carbides can be detected by the presence of two broad Raman lines 1370 and 1580 cm−1. In the hot‐pressed samples that exhibited the lines the carbonaceous material is amorphous and much like carbon black or pyrolytic glass...