Lattice parameters were shown to increase linearly with the increase in temperature, with c parameter showing a significant increase than a and b cell parameters. This is attributed to the cumulative effect of stacking of layers along the c crystallographic direction and c axis being less restricted by the expansion of the rock-salt layers. A further observation of the b parameter showing only a slight increase as compared to a parameter is interpreted in terms of an increase in orthorhombic strain with the increase in temperature. The calculated TEC based on neutron diffraction measurements was found to be around 13.0 × 10 -6 ˚C-1 , which is of the same order as that of commonly used electrolyte materials in SOFC devices. Furthermore, neutron diffraction and DFT calculations both suggested that vacancies prefer the perovskite block -O(1) and O(3) sitesand it, in fact, has been reported earlier that majority of the oxygen vacancies in these materials are confined to the perovskite layers, with a particular preference to equatorial oxygen sites. A further strong preference for the curved oxygen transport pathways such as O(1)-O(1)-O(1) around the NiO6 octahedra was recorded, in consonance with the earlier reports in these materials.