Wydział Chemii

Maciej Wojtaś

Anna Gągor

Olaf Czupiński

Wojciech Medycki

Ryszard Jakubas

2012

Journal of Solid State Chemistry

187

35-44

10.1016/j.jssc.2011.12.020

Naukowa

Angielski

Artykuł

Dielectric properties and phase transitions of the piperazinium tetrafluoroborate (, abbreviated as PFB) crystal are related to the one-dimensional arrangement of the cations linked by the bistable hydrogen bonds and molecular motions of the units. The crystal structure of is monoclinic at room temperature with the polar space group Pn. The polar/acentric properties of the room temperature phase IV have been confirmed by the piezoelectric and pyroelectric measurements. DSC measurements show that the compound undergoes three first-order structural phase transitions: at 421/411 K (heating/cooling), at 386/372 K and at 364/349 K. ¹H and ¹⁹F NMR measurements indicate the reorientational motions of anions and piperazinium(+) cations as well as the proton motion in the hydrogen-bonded chains of piperazine along the [001] direction. Over the phase I the isotropic reorientational motions or even self-diffusion of the cations and anions are expected. The conductivity measurements in the vicinity of the II–I PT indicate a superionic phase over the phase I.

Hybrid material, Single-protonated piperazinium cation, NLO

https://doi.org/10.1016/j.jssc.2011.12.020

http://www.elsevier.com