Intermediate-Range Order in Amorphous Phosphorus

Neutron diffraction measurements have been made for two samples of amorphous red phosphorus available as commercial products. The sample prepared at low temperature (280-degrees-C) was violet in colour and exhibited a typically amorphous scattering pattern, giving a pair correlation function that displayed clear peaks for first and second neighbours with a more complex behaviour at higher r-values ( > 6 angstrom). The sample prepared at higher temperature was red-brown in colour and showed evidence of some sharp Bragg peaks superimposed on an amorphous scattering pattern; the corresponding real-space distribution had similar features but displayed enhanced intermediate range order in the range 8-18 angstrom. The results suggest that the network and its connectivity is more complex than for the group IV elemental amorphous solids.