期刊
CRYSTAL GROWTH & DESIGN
卷 16, 期 12, 页码 7212-7217出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.cgd.6b01404
关键词
-
资金
- NSFC [21290173, 21301198, 91422302]
- NSF of Guangdong [S2012030006240]
Two new perovskite-like coordination polymers, A(2)[KFe(CN)(6)], were constructed by employing guanidinium and acetamidinium as A-site cations, respectively. Their cation-controlled two-step phase transitions as well as the relevant dielectric responses were uncovered by the combined techniques of the variable-temperature single-crystal X-ray structural analyses and dielectric measurements. With a similar size and shape, the A-site cations reveal similar two-step thermal-induced transitions on their motional dynamics, i.e., from a frozen order state to an in-plane rotational disorder state, and to a melt-like disorder state. However, the variation of the A-site cations on their symmetries and dipole moments makes noticeable impacts on the symmetry breaking, the critical temperatures, and the dielectric responses for the two-step structural phase transitions, i.e., the D-3h nonpolar guanidinium results in an R (3) over barc <-> R (3) over barm <-> Fm (3) over barm transition, whereas the C-2v polar acetamidinium results in a C2/m <-> R (3) over barm <-> Fm (3) over barm transition. Investigations of these two coordination polymers demonstrate a fine modulation on the phase transition behaviors and dielectric responses by changing the symmetries and dipole moments of A-site cations.
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