Ferroelectricity and Related Properties of Nitratecadmate(II) Hybrid with Metal-Vacancy

All crystals are not ideal, and many of their properties are often determined not by the regular arrangement of atoms, but by the irregular arrangement of crystal defects. Many properties of materials can be controlled effectively by proper use of solid defects. By substitution of NH4+ ion of a hexagonal perovskite structure (H2dabco)(NH4)(NO3)3 (dabco=1,4-diazabicyclo[2.2.2]octane, 1) with Cd2+ ion, we obtained a new metal-vacancy compound (H2dabco)2Cd(H2O)2(NO3)6 (2). It exhibits a ferroelectric-paraelectric phase transition at 261 K. A comparison of the various-temperature single-crystal structures indicates that the coordination twist of Cd2+ ion leads to instability of the lattices and excellent ferroelectricity. These findings reveal that the vacancy can be utilized as an element to produce ferroelectricity and may start the chemistry of metal-vacancy coordination compounds. These findings reveals that the vacancy can be utilized as an effective means to tune the symmetry and produce ferroelectricity. By substitution of NH4+ ion of a hexagonal perovskite structure with Cd2+ ion, we obtained a new metal-vacancy compound (H2dabco)2Cd(H2O)2(NO3)6. The coordination twist of the Cd-vacancy leads to instability of the lattices, structural phase transitions and excellent ferroelectricity. This result reveals that the vacancy can be utilized as an element to produce ferroelectric complexes.image