A displacive-type metal crown ether ferroelectric compound: Ca(NO3)2(15-crown-5).
Following the Curie symmetry principle and Aizu rule, we discovered there is a centrosymmetric-to-noncentrosymmetric phase transition in Ca(NO3)2(15-crown-5) at Tc = 205 K. The transition was confirmed by differential scanning calorimetry and second harmonic generation measurements. The transition gives rise to excellent ferroelectricity, such as a giant dielectric anomaly, with faster polarization switching (5×10(-5) s) of up to 10(7) times without showing fatigue. The ferroelectric mechanism is attributable to the coordination environmental distortion of the central Ca atom. This finding can throw light on the further research in metal-organic ferroelectrics.
Ordered Matter Science Research Center, Southeast University, Nanjing 211189 (P.R. China).
Heng-Yun
HY
Ye
Yi
Y
Zhang
Da-Wei
DW
Fu
Ren-Gen
RG
Xiong
coordination distortion; crown-ether complexes; dielectricity; ferroelectricity; structural phase transitions