Although Goldschmidt tolerance variables can semi-quantitatively forecast structural distortion on the basis of steric hindrance in 3D perovskites, It's not necessarily easy to use to 2D perovskites, since the layered segregated structures in 2nd perovskites enable the incorporation of greater natural and organic cations in to the inorganic cages26,27,28,29,30. The https://crithitceramics.com/product/fireball/