Neutron diffraction studies and DFT calculations of three novel higher-order Ruddlesden-Popper phases were discussed. Across these newly synthesised compositions, it was observed that the lattice parameters show a systematic decrease with an increase in the Pr content of the composition, which agrees with the conception of effective ionic radii of Pr 3+ being less than the corresponding La 3+ . L1P3N3 and L2P2N3 compositions were found to crystallise in the orthorhombic Bmab/Fmmm space group, with only L3P1N3 showing transition to higher symmetry tetragonal I4/mmm space group at 800˚C. L2P2N3 composition, however, was found to crystallise in monoclinic symmetry. It was also observed that orthorhombic strain in these materials increases with the increase in the Pr content of the composition. This is expected and is because of the decrease in ionic radii of Pr.