The proton conductivity in benzimidazolium azelate under moderate pressure

Abstract

The kinetic Monte Carlo method is applied to examine effects of hydrostatic pressure on the benzimidazolium azelate (BenAze) proton conductivity. Following the experimental indications the recently proposed model has been modified to simulate the transport phenomena under moderate pressure, resulting in a very good agreement between numerical and experimental results. We demonstrate that the pressure-induced changes in the proton conductivity can be attributed to solely two parameters: the length of the hydrogen bond and the amplitude of lattice vibrations while other processes play a more minor role. It may provide an insight into tailoring new materials with improved proton-conducting properties. Furthermore, in high-pressure regime we anticipate the crossover from the increasing to decreasing temperature dependence of the proton conductivity resulting from the changes in the hydrogen-bond activation barrier with increased pressure.

A Closer Look at Structural Relaxation in Superionic (NH4)4H2(SeO4)3: 1H NMR Studies

“…It is worth noting that the change in the electric properties of the TeAHSe crystals from poor conductor to superionic one is a result of a weakening of the N–H···O subnetwork created by NH 4 + cations. These N–H···O bonds are long, weak, and unstable even at room temperature, so NH 4 + and SeO 4 – orientational disorder at high temperatures leads to these bonds’ elongation , and, in consequence, to the diffusion of ammonium cations.…”

“…Therefore, the ammonia cations diffusion in the TeAHSe bulk should be very well visible in the temperature dependence of the 1 H NMR absorption signal moments ratio M 4 /M 2 2 . Figure 6 − orientational disorder at high temperatures leads to these bonds' elongation 19,20 and, in consequence, to the diffusion of ammonium cations.…”

“…These results indicate that the change in electrical properties of the (NH 4 ) 4 H 2 (SeO 4 ) 3 crystal from an insulator to a superionic conductor is closely related to the dynamic processes taking place in the subnetwork of H-bonds created by NH 4 cations. The effective shape of the H-bond potential, which is the main factor responsible for the proton diffusion, comes from the interplay of the H-bond length and the amplitude of lattice vibrations and may not be limited to a static situation. , The N–H···O bonds are long, and the subnetwork they form is weak. Even a small change in temperature may significantly change the H-bond potential which trapped protons and NH 4 ions.…”

The AC Conductivity and the Jonscher Exponent in the One-Dimensional Model of Proton Conductivity

“…To get the Jonscher exponent n ∼ 0.3-0.4, characteristic for the nearest neighbours interaction [8], the interaction cannot be limited to isolated events in time. The Coulomb interaction in the form presented in the model is sufficient to explain the macroscopic properties [1][2][3] but it cannot go beyond a free evolution in the case of AC conductivity which is subjected to microscopic phenomena. Fig.…”

“…The kinetic Monte Carlo (KMC) method has proven its predictive power in applications to the dc conductivity of proton conductors [1][2][3]. Models adopting KMC effectively take into account a diverse spectrum of factors responsible for proton migration like the shape of hydrogen bond potential, lattice vibration, or thermal expansion of the medium and thus may support experiments with the proper interpretation of the data as well as a prediction of new phenomena.…”