Bismuth niobium oxide (BiNbO4) is widely used in multilayer radio frequency and microwave components such as chip LCs and capacitors. While the low temperature forms of this compound are well known, we have recently identified two additional forms at high temperature. In a previous experiment we were able to structurally characterise the first of these (gamma-BiNbO4), which is seen at temperatures between 1000 deg. C and 1150 deg. C. The present proposal seeks to complete this study with characterisation of the other high temperature phase (delta-BiNbO4) seen above 1150 deg. C.