H/F Substitution Induced Large Increase of T_c in a 3D Hybrid Rare-Earth Double Perovskite Multifunctional Compound

Increasing attention has been devoted to studying perovskite-type multifunctional stimuli-responsive materials with multiple channel physical characteristics. However, it remains challenging to simultaneously achieve multifunction and regulate structural phase transition temperature in hybrid perovskites. Here, we report two three-dimensional organic-inorganic hybrid rare-earth double perovskite compounds, (HQ)₂ RbEu(NO₃ )₆ (1, HQ=quinuclidium) and (4FHQ)₂ RbEu(NO₃ )₆ (2, 4FHQ=4-fluoro-quinuclidium), which exhibit ferroelasticity, dielectric switch, and excellent photoluminescence response. The phase transition temperature of 2 increases 169 K compared with 1 through H/F substitution. This result is attributed to the H/F substitution inducing the generation of the Rb-F coordination bond between cations and anions. Meanwhile, the photoluminescence emission intensity of 2 shows no quench with the increase of temperature, in particular, the emission spectrum achieves fine regulation at high temperatures. This work provides a new solution for the realization of multi-functions and regulations of the properties based on hybrid perovskite materials with high critical temperatures.