While Goldschmidt tolerance elements can semi-quantitatively predict structural distortion on The premise of steric hindrance in 3D perovskites, It's not clear-cut to apply to 2D perovskites, since the layered segregated buildings in second perovskites enable the incorporation of more substantial natural and organic cations in to the inorganic cages26,27,28,29,30. The https://crithitceramics.com/product/fireball/