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High-temperature phase transitions, switchable dielectric behaviors and barocaloric effects in three new organic molecule-based crystals

Authors :
Xuan Zheng
Da-Wei Fu
Ping-Ping Shi
Lin Zhou
Qiong Ye
Rui-Xia Li
Ji-Xing Gao
Source :
New Journal of Chemistry. 43:154-161
Publication Year :
2019
Publisher :
Royal Society of Chemistry (RSC), 2019.

Abstract

Three new organic molecule-based compounds, ethyl-trimethyl-phosphonium picrate (1, [ETtmp][picrate]), hydroxymethyl-trimethyl-phosphonium picrate (2, [HMtmp][picrate]), and cyclopentyl-trimethyl-phosphonium picrate (3, [CPtmp][picrate]), have been corroborated as high-temperature phase transition materials possessing switchable dielectric behaviors. Compounds 1, 2 and 3 undergo dielectric anomalies which could be tuned in two pronounced dielectric states and switched by reversible phase transitions at 320.8 K, 393.9 K and 398.1 K, respectively. For compounds 1, 2 and 3, not only the phase transition temperatures but also the magnitudes of the dielectric anomalies presented variations by regulating the guest cations. The respective dielectric constants in the high dielectric states are 1.6, 2.7 and 3.6 times those in the low dielectric states for compounds 1, 2 and 3. And considering the big entropy changes (ΔS) in the three title compounds, we predicted the sensitivities of the phase transition temperatures (Tc) to the applied pressure. And the estimated barocaloric coefficients (δTc/δP) in the three title compounds indicate that they potentially perform barocaloric effects of interest for cooling applications under adequate pressure.

Details

ISSN :
13699261 and 11440546
Volume :
43
Database :
OpenAIRE
Journal :
New Journal of Chemistry
Accession number :
edsair.doi...........abd3b1e3554e9363fff2926f4351ec2b
Full Text :
https://doi.org/10.1039/c8nj03845g