New ferroelectric inorganic materials predicted in point group 4mm

The Inorganic Crystal Structure Database containing a total of 209 entries for 128 different materials reported in point group 4 mm, of which eight are for previously known ferroelectrics. Analysis of the remaining entries, assuming the structure determinations reported are correct, leads to the prediction of an additional 43 new ferroelectric materials. 15 were determined in space group P4mm, 11 in P4bm, one in P4₂nm, one in P4cc, two in P4₂mc, one in P4₂bc, seven in I4mm, two in I4cm, one in I4₁md and two in I4₁cd. Numerous other structures are shown to have been assigned, most likely, to an incorrect space group. All but one of the materials reported in space group P4bm are predicted to be ferroelectric. New ferroelectrics predicted in point group 4 mm include K₂[Pt(CN)₄]Br_0.3.3H₂O, Nd_0.33TaO₃, YBaCuFeO_5+δ, Ba₂(TiO)(Si₂O₇), K₂(NbO)₂(SiO₃)₄, Ba₆CoNb₉O₃₀, Sr₂SbMnO₆, Hg₂AlF₅.(H₂O)₂, Rb₅Nb₃OF₁₈ and SrNi₂(VO₄)₂.

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