Systematic prediction of new inorganic ferroelectrics in point group 4

The latest release of the Inorganic Crystal Structure Database contains a total of 87 entries corresponding to 70 different materials in point group 4. The structures reported for 11 materials in space group P4 satisfy the criteria for ferroelectricity, as do four in P4₁, one each in P4₂ and P4₃, 12 in I4, including seven that form three families, and another three in I4₁. Three previously known ferroelectrics were also listed in I4 and one in I4₁. In addition, the listing for point group 4 contains 22 entries for nonferroelectric materials and three with misassigned space groups. Among the newly predicted ferroelectrics in point group 4, assuming the validity of the underlying structural reports, are Ce₅B₂C₆, modulated NbTe₄, Na₃Nb₁₂O₃₁F, Ca₂FeO₃Cl, K₄CuV₅O₁₅Cl, TlBO₂, CrOF₃, PbTeO₃, VO(HPO₃)(H₂O).3H₂O, MgB₂O(OH)₆, β-tetragonal boron, CuBi₂O₄, WOBr₄, Na₈PtO₆, SbF₂Cl₃, Ba_1.2Ti₈O₁₆, Ni[SC(NH₂)₂]₄Cl₂, Ca₂SiO₃Cl₂, the mineral caratiite, NbAs, β-NbO₂ and Ag₃BiO₃.