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High-temperature molecular ferroelastic phase transition and switchable dielectric response in the trimethylbromomethylammonium salt [C4H11NBr] [PF6]

Abstract

By introducing halogens to the 16 symmetric tetramethylammonium, one new molecular ferroelastic [TMBMA][PF6] (1) (TMBMA= trimethylbromomethylammonium) was successfully synthesized. Differential scanning calorimetry (DSC) measurements demonstrated that 1 underwent a typically first-ordered phase transition at ca. 380 K with a large thermal hysteresis of 30 K. Single crystal X-ray diffraction date, the variable-temperature powder X-ray diffraction (PXRD) patterns and the complex domain-wall orientations suggested that the phase transition from monoclinic (P21/c) to cubic (Pm3 @#x0305;m) belongs to ferroelastic phase transition with an Aizu notation of m3 @#x0305;mF2/m. Dielectric studies illustrate that 1 displays distinctly switchable dielectric behavior and satisfactorily thermal stability, revealing the potential application in dielectric switches. As expected, the TMBMA cations bearing an ordered-disordered motion turns out to be crucial in the generation of the ferroelastic phase transition. Therefore, this molecular design strategy by introducing halogens to tetraalkylammoniums can not only reduce the symmetry of the tetraalkylammoniums molecular at room temperature, but also keep the highly disordered characteristics at high temperature. This provides an efficient route for us to find new molecular ferroelastics and dielectric switches.

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Publication details

The article was received on 28 May 2018, accepted on 01 Aug 2018 and first published on 02 Aug 2018


Article type: Paper
DOI: 10.1039/C8NJ02645A
Citation: New J. Chem., 2018, Accepted Manuscript
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    High-temperature molecular ferroelastic phase transition and switchable dielectric response in the trimethylbromomethylammonium salt [C4H11NBr] [PF6]

    X. Chen, J. Gao, X. Hua and W. Liao, New J. Chem., 2018, Accepted Manuscript , DOI: 10.1039/C8NJ02645A

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