A room-temperature moisture-stabilized metal-free energetic ferroelectric material for piezoelectric generation

Abstract

Metal-free molecule-based ferroelectrics with tunable structure, low production cost, "soft" texture, and degradability have prospects for sensing and piezoelectric generation applications, but the instances integrating multiple functionalities are very rare....

A hybrid double perovskite ferroelastic exhibiting the highest number of orientation states

“…23 For instance, we have previously showcased a novel, designable bond-switching phase transition in multiaxial ferroelectrics (Me 3 NOH) 2 [KB′′(CN) 6 ] (B′′ = Fe 3+ , Co 3+ ), characterised by the cleavage and reformation of N–O–K coordination bonds between B′-site (K + ) and A-site (Me 3 NOH + ) cation, leading to 24 equivalent polarization directions. 24,25 More recently, the ammonium cation, NH 4 + , has been identified as a potential B-site ion to construct metal-free perovskites, such as (C 4 H 12 N 2 )(NH 4 )Cl 3 , 26 (C 7 N 2 H 16 )(NH 4 )I 3 , 27 (C 7 N 2 H 16 )(NH 4 )(PF 6 ) 3 , 28 (C 6 N 2 H 14 )(NH 4 )(ClO 4 ) 3 , 29–31 and (C 6 N 2 H 14 )(NH 4 )(IO 4 ) 3 . 32 The ionic radius and spherical symmetry of the conventional B-site metal ion and the molecular ion NH 4 + are similar, enabling the crystals to adopt the prototypical perovskite structure.…”