Ferroelectric materials, in which the polarization may be switched, are an important class of compounds due to their academic and technological relevance. The mechanisms that give rise to the polarization include cation displacements, cation ordering patterns and combinations of octahedral rotations. There has been much interest recently in materials that show hybrid-improper ferroelectricity, in which two non-polar lattice distortions (e.g. octahedral rotational modes) give rise to polar structures. We have recently investigated some Dion-Jacobson oxides in which the width of the perovskite blocks influences whether the ferroelectricity will be of a proper, or an improper nature. We propose to investigate the new material RbBi2Ti2NbO10 and its structural behaviour as a function of temperature to understand the driving forces for proper and improper mechanisms for ferroelectricity.