Structure of pressure compacted vitreous boron oxide

The structure of pressure compacted vitreous B 2 O 3 has been studied by neutron diffraction using the LAD spectrometer at the ISIS spallation pulsed neutron source to provide the necessary high real space resolution to investigate small changes in interatomic distances and coordination numbers. The data are in excellent agreement with previous x-ray diffraction results but of much higher real space resolution. The density compaction results from the break up of boroxol groups with increasing pressure but, once the pressure is released, pressure compacted vitreous B 2 O 3 relaxes over a period of several days during which the original boroxol ring fraction is restored.