Topochemical fluorination of some Ruddlesden-Popper phases by Zhang, R

“…The introduction of a cooperative octahedral tilt around the crystallographic z-axis leads to a local breaking of the inversion symmetry of the host lattice on fluorination, although the global inversion symmetry of the lattice is retained due to an alternation in the z-tilt direction in adjacent perovskite sheets.</p> <p>The substitution of Sr²⁺ with Ca²⁺ cations in YSr₂Mn₂O₇ led to an increasing distortion of the metal-oxide framework, resulting in the formation of an orthorhombic symmetry in space group <em>Pnnm</em> adopted by YSr_0.5Ca_1.5Mn₂O₇. …”