STRUCTURE OF AMORPHOUS BORON

The short range order structure of amorphous boron is studied. Three sample materials of different appearances, film, whisker and fiber, are prepared by chemical vapor depositon by the reduction of BCl3 with hydrogen. The reduced radial distribution functions (reduced RDFs derived from their x-ray or electron diffraction patterns are found to be almost identical among the three samples. The reduced RDFs are compared with those calculated for the four crystalline modifications of boron, i.e. α-rhombohedral, α-tetragonal, β-tetragonal and β-rhombohedral boron. The reduced RDFs of amorphous boron are found to be similar to those of the β-tetragonal and β-rhombohedral boron. From the similarity of physical and chemical properties and co-existence in depsition, the short range order structure of amorphous boron is shown to be closer to that of the β-rhombohedral modification