Considering the deviation from the ideal cationic composition in cubic-BaSnF4 and the larger ionic radius of Ba 2+ as compared to Sn , we used a model with inhomogeneous distributions of Ba and Sn on the cation sites in the formed t-BaSnF4 phase after annealing, where the occupancy of Ba at the Sn1 site can lead to an expansion along the c-axis within the unit cell.