To meet the de ma nds of high stability and sustainable temperature measurements over time,TIPC-CAS in China and LNE-Cnam in France have jointly developed single-pressure refractive-index gas thermometiy(SPR1GT),which...To meet the de ma nds of high stability and sustainable temperature measurements over time,TIPC-CAS in China and LNE-Cnam in France have jointly developed single-pressure refractive-index gas thermometiy(SPR1GT),which is expected to be an alternative primary thermometiy because of its 0.25 mK accuracy and high measurement speeds.展开更多
Molecular ferroelectrics have attracted much attention because of their excellent piezoelectricity,mechanical workability,and second harmonic effect.Here,we successfully prepared two molecular ferroelectrics[1,5-3.2.2...Molecular ferroelectrics have attracted much attention because of their excellent piezoelectricity,mechanical workability,and second harmonic effect.Here,we successfully prepared two molecular ferroelectrics[1,5-3.2.2-Hdabcn]X(X=ClO_(4)^(-),1;ReO_(4)^(-),2)by reactions of a quasi-spherical amine 1,5-diazabicycle[3.2.2]nonane(1.5-3.2.2-dabcn)with HX aqueous solution.Compounds 1 and 2 undergo hightemperature phase transitions at 381 K(1)and 396 K(2).Before and after the phase transition,they crystallize in the polar point group mm2,and the centrosymmetric point groups mmm and 4/mmm,respectively.According to Aizu rules,these two compounds experience mmm Fmm2 and 4/mmm Fmm2 type ferroelectric phase transitions,respectively.The ferroelectricity of both compounds is well expressed in their polycrystalline film at room temperature with low coercive voltages of 13 V for 1 and 25 V for 2.Using piezoelectric force microscopy(PFM),the 180°anti-parallel ferroelectric domains and the reversible polarization switching can be clearly observed in 1 and 2.This high-temperature molecular ferroelectric material has great application potential in flexible materials,biomechanics,intelligent wearables and other fields.展开更多
基金supported by the National Key R&D Program of China(2016YFE0204200)the National Natural Science Foundation of China(51627809)+2 种基金the International Partnership Program of the Chinese Academy of Sciences(1A1111KYSB20160017)the European Metrology Research Programme(EMRP)(InK2)(No.15SIB02)the China Postdoctoral Science Foundation(2017LH031)
文摘To meet the de ma nds of high stability and sustainable temperature measurements over time,TIPC-CAS in China and LNE-Cnam in France have jointly developed single-pressure refractive-index gas thermometiy(SPR1GT),which is expected to be an alternative primary thermometiy because of its 0.25 mK accuracy and high measurement speeds.
基金supported by the National Natural Science Foundation of China(Nos.21865015,22071094 and 22075123)the Department of Science and Technology in Jiangxi Province(No.20213BCJ22055)。
文摘Molecular ferroelectrics have attracted much attention because of their excellent piezoelectricity,mechanical workability,and second harmonic effect.Here,we successfully prepared two molecular ferroelectrics[1,5-3.2.2-Hdabcn]X(X=ClO_(4)^(-),1;ReO_(4)^(-),2)by reactions of a quasi-spherical amine 1,5-diazabicycle[3.2.2]nonane(1.5-3.2.2-dabcn)with HX aqueous solution.Compounds 1 and 2 undergo hightemperature phase transitions at 381 K(1)and 396 K(2).Before and after the phase transition,they crystallize in the polar point group mm2,and the centrosymmetric point groups mmm and 4/mmm,respectively.According to Aizu rules,these two compounds experience mmm Fmm2 and 4/mmm Fmm2 type ferroelectric phase transitions,respectively.The ferroelectricity of both compounds is well expressed in their polycrystalline film at room temperature with low coercive voltages of 13 V for 1 and 25 V for 2.Using piezoelectric force microscopy(PFM),the 180°anti-parallel ferroelectric domains and the reversible polarization switching can be clearly observed in 1 and 2.This high-temperature molecular ferroelectric material has great application potential in flexible materials,biomechanics,intelligent wearables and other fields.
