Two hybrid crystals imidazolium iodoantimonate(Ⅲ)and iodobismuthate(Ⅲ),(C_(3)H_(5)N_(2))_(3)[Sb_(2)I_(9)](ImIA)and(C_(3)H_(5)N_(2))_(3)[Bi_(2)I_(9)](ImIB),have been synthesized and characterized in a wide temperatur...Two hybrid crystals imidazolium iodoantimonate(Ⅲ)and iodobismuthate(Ⅲ),(C_(3)H_(5)N_(2))_(3)[Sb_(2)I_(9)](ImIA)and(C_(3)H_(5)N_(2))_(3)[Bi_(2)I_(9)](ImIB),have been synthesized and characterized in a wide temperature range(100-350 K)by means of X-ray diffraction,dielectric spectroscopy,proton magnetic resonance(^(1)H NMR),FT-IR spectroscopy and optical observations.They undergo two temperature induced solid-solid structural phase transitions.The first one,quasi-continuous(with temperature hysteresis below 1 K),occurs at 324 K in ImIA and 327 K in ImIB,and the second one,clearly of the first order,at 273/278(cooling/heating)and 291/295 K,in ImIA and ImIB,respectively.Ferroelastic properties are maintained in lowtemperature phases.Both materials are isomorphic in the corresponding phases.High temperature phaseⅠhas a hexagonal P63/mmc symmetry,and phaseⅡhas orthorhombic Cmcm.The crystal architecture is composed of discrete,face-sharing bioctahedra[M_(2)I_(9)]^(3−)(M:Sb,Bi)and imidazolium cations which are highly disordered over phasesⅠandⅡ.The dynamics of the imidazolium cations has a prominent impact on the stability of the particular phases.展开更多
基金supported by the National Science Centregrant no.2013/11/D/ST8/03297(A.Piecha-Bisiorek).
文摘Two hybrid crystals imidazolium iodoantimonate(Ⅲ)and iodobismuthate(Ⅲ),(C_(3)H_(5)N_(2))_(3)[Sb_(2)I_(9)](ImIA)and(C_(3)H_(5)N_(2))_(3)[Bi_(2)I_(9)](ImIB),have been synthesized and characterized in a wide temperature range(100-350 K)by means of X-ray diffraction,dielectric spectroscopy,proton magnetic resonance(^(1)H NMR),FT-IR spectroscopy and optical observations.They undergo two temperature induced solid-solid structural phase transitions.The first one,quasi-continuous(with temperature hysteresis below 1 K),occurs at 324 K in ImIA and 327 K in ImIB,and the second one,clearly of the first order,at 273/278(cooling/heating)and 291/295 K,in ImIA and ImIB,respectively.Ferroelastic properties are maintained in lowtemperature phases.Both materials are isomorphic in the corresponding phases.High temperature phaseⅠhas a hexagonal P63/mmc symmetry,and phaseⅡhas orthorhombic Cmcm.The crystal architecture is composed of discrete,face-sharing bioctahedra[M_(2)I_(9)]^(3−)(M:Sb,Bi)and imidazolium cations which are highly disordered over phasesⅠandⅡ.The dynamics of the imidazolium cations has a prominent impact on the stability of the particular phases.
