Structural phase transitions and switchable dielectric constants of two ionic co-crystals (am)(3)[La(NO3)(6)] (am = (n-Pr)(3)NH, (n-Bu)(3)NH)

摘要

The reaction of La(NO3)(3)center dot 6H(2)O and [(n-Pr)(3)NH](NO3) or [(n-Bu)(3)NH](NO3) afforded two ionic co-crystal compounds, namely [(n-Pr)(3)NH](3)[La(NO3)(6)] and [(n-Bu)(3)NH](3)[La(NO3)(6)], respectively. Both compounds show switchable dielectric behaviors above room temperature, owing to their reversible structural phase transitions confirmed by DSC measurement and variable-temperature powder X-ray diffraction. The former compound can function as a thermosensitive dielectric material over a wide temperature range above room temperature, while the latter may act as a bistable dielectric material with a large epsilon'-T hysteresis loop. The synthetic approach affords an effective strategy to construct switchable dielectric phase transition materials based on large ammonium and lanthanide complex anion.