Geometric ferroelectrics are an unusual and rare class of materials which exhibit spontaneous electrical polarisation due purely to 'geometric' effects, i.e. caused by atomic size mismatch, rather than 'electronically' driven factors. The compound LaTaO4 is one case, which is particularly unusual in showing a transition to such a state on INCREASING, rather than decreasing temperature. In this proposal we seek to characterise two new compounds, distinct from, but closely related to LaTaO4, which we believe may show a similar 'geometry-induced' electrical polarisation. The apparent phase transition of one of these, has previously been overlooked in the literature. We will use high-resolution powder neutron diffraction to ascertain whether these new materials do indeed display this unusual behaviour.