Towards accurate B–O coordination numbers and structure-property relations in borate liquids

High-energy x-ray diffraction can provide accurate B-O coordination numbers, nBO, based on mean B–O bond lengths, rBO. Measuring temperature dependence of these in liquid borates allows enthalpies & entropies of isomerization to be extracted, & these connect directly to configurational properties such as heat capacity & entropy, which play a key role in viscous flow. This procedure relies on accurate knowledge of the thermal expansion of the B–O bond. Here we propose to measure the temperature dependent structure of liquid B2O3 using neutrons, in order to verify the rBO(T) obtained with x-rays, & to ensure that future neutron measurements of borate liquids can be used to derive structure-property relationships. We will also calculate x-ray-neutron difference functions, giving access to nearest-neighbour B–B distances, & unique insight into the boroxol ring dissolution mechanism.