Hybrid ferroelastic crystals have garnered considerable interest due to their promising potential as mechanical switches and sensors.The anomalous ferroelastic phase transitions,in which ferroelasticity occurs in the ...Hybrid ferroelastic crystals have garnered considerable interest due to their promising potential as mechanical switches and sensors.The anomalous ferroelastic phase transitions,in which ferroelasticity occurs in the hightemperature phase rather than the low-temperature phase,are of particular interest,but they are sporadically-documented and none of them is involved in breaking of the chemical bonds.Herein,a hydroxyl-containing cation,i.e.,Me_(3)NOH^(+),is employed to construct a three-dimensional hybrid crystal(Me_(3)NOH)_(2)KBiCl_(6)(1).This crystal undergoes distinct twostep structural phase transitions with space-group changes of Pna21–P112_(1)–P63mc,belonging to an anomalous temperaturereversed mm2F2 ferroelastic transition and a normal 6mmF2 ferroelastic transition,respectively.The anomalous ferroelastic transition is entirely driven by switchable K–O coordination bonds involving breaking and reformation.Notably,the dynamic behavior of Me_(3)NOH^(+)cations along with the distortion of inorganic framework enables the manifestation of unusual“high-low-medium”second-harmonic generation-switching behaviors.This study presents the enormous benefits of switchable coordination bonds for inducing anomalous ferroelastic phase transitions,offering valuable insight for the exploration of new multifunctional ferroelastic materials.展开更多
基金supported by the National Natural Science Foundation Of China(22071273 and 21821003)the Fundamental Research Funds for the Central Universities,Sun Yat-Sen University(23lgzy001).
文摘Hybrid ferroelastic crystals have garnered considerable interest due to their promising potential as mechanical switches and sensors.The anomalous ferroelastic phase transitions,in which ferroelasticity occurs in the hightemperature phase rather than the low-temperature phase,are of particular interest,but they are sporadically-documented and none of them is involved in breaking of the chemical bonds.Herein,a hydroxyl-containing cation,i.e.,Me_(3)NOH^(+),is employed to construct a three-dimensional hybrid crystal(Me_(3)NOH)_(2)KBiCl_(6)(1).This crystal undergoes distinct twostep structural phase transitions with space-group changes of Pna21–P112_(1)–P63mc,belonging to an anomalous temperaturereversed mm2F2 ferroelastic transition and a normal 6mmF2 ferroelastic transition,respectively.The anomalous ferroelastic transition is entirely driven by switchable K–O coordination bonds involving breaking and reformation.Notably,the dynamic behavior of Me_(3)NOH^(+)cations along with the distortion of inorganic framework enables the manifestation of unusual“high-low-medium”second-harmonic generation-switching behaviors.This study presents the enormous benefits of switchable coordination bonds for inducing anomalous ferroelastic phase transitions,offering valuable insight for the exploration of new multifunctional ferroelastic materials.
