Crystal engineering regulation achieving inverse temperature symmetry breaking ferroelasticity in a cationic displacement type hybrid perovskite system

Ferroelastic hybrid perovskite materials have been revealed the significance in the applications of switches,sensors,actuators,etc.However,it remains a challenge to design high-temperature ferroelastic to meet the requirements for the practical applications.Herein,we reported an one-dimensional organicinorganic hybrid perovskites(OIHP)(3-methylpyrazolium)CdCl_(3)(3-MBCC),which possesses a mmmF2/m ferroelastic phase transition at 263 K.Moreover,utilizing crystal engineering,we replace-CH_(3) with-NH_(2) and-H,which increases the intermolecular force between organic cations and inorganic frameworks.The phase transition temperature of(3-aminopyrazolium)CdCl_(3)(3-ABCC),and(pyrazolium)CdCl_(3)(BCC)increased by 73 K and 10 K,respectively.Particularly,BCC undergoes an unconventional inverse temperature symmetry breaking(ISTB)ferroelastic phase transition around 273 K.Differently,it transforms from a high symmetry low-temperature paraelastic phase(point group 2/m)to a low symmetry high-temperature ferroelastic phase(point group ī)originating from the rare mechanism of displacement of organic cations phase transition.It means that crystal BCC retains in ferroelastic phase above 273 K until melting point(446 K).Furthermore,characteristic ferroelastic domain patterns on crystal BCC are confirmed with polarized optical microscopy.Our study enriches the molecular mechanism of ferroelastics in the family of organic-inorganic hybrids and opens up a new avenue for exploring high-temperature ferroic materials.

Wavelength and polarization dual-multiplexed imaging based on holographic metasurfaces

In light of the powerful light manipulation ability of holographic metasurfaces,optical imaging with wavelength multiplexing and polarization multiplexing is performed in this paper.The metasurface is composed of identical rectangular nanoholes etched in silver film.Three imaging effects,including the in-plane color imaging,three-dimensional wavelength-encrypted imaging,and polarization-multiplexing wavelength-encrypted imaging,are realized.The designed metasurface has compact structure,and the obtained image has lower noise.The simulation and experiment results give the verification.Multiple images,including spatial multiplexing,wavelength multiplexing,and polarization multiplexing,exhibit immense potentialities of metasurfaces,and this work is helpful for expanding the applications of metasurfaces.