Short-range order (SRO) structures of various grades of amorphous boron show similar undulations an their reduced radial distribution functions (G(r)(obs)s). The profiles of these undulations resemble those derived from the structure models of beta-rhombohedral boron, beta-tetragonal boron, and a giant cluster made up of 13 B-12 units. From this examination, the interconnected B-48-(Td) unit, which is a main substructure of all the structure models mentioned above, seemed to be responsible for the similar undulations. In this work, however, structure simulation of amorphous boron was made solely with the B-12 icosahedron. Two series of boron cluster models were considered based on the difference in their bonding state through pseudo-fivefold axes, i.e., ''in-phase'' without rotation and ''out-of-phase'' differing by similar to pi/5. The G(r)(calc) were calculated by means of the Fourier integral of the interference intensity functions wherein the scattering intensities were derived through a partly modified Debye's scattering intensity equation. From the comparison of the SRO structures of the cluster models to those for amorphous boron, it is indicated that the number and the bonding state of the icosahedra which constitute the boron cluster should be greater than 9-13 and should be in out-of-phase state for better correspondence. (C) 1997 Academic Press. [References: 5]
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