Studies of the anisotropic self-diffusion and reorientation of butylammonium cations in the rotator phase of butylammonium chloride using 1H magnetic resonance, electrical conductivity and thermal measurements

Abstract

Butylammonium chloride crystals annealed by slowly scanning through the phase transitions many times have been shown to exhibit a simple thermogram, having a single phase transition at 241 K (Tt,.) on heating from ca. 100 K up to the melting temperature T, (487 K). Another additional thermal treatment was made on the annealed crystals, then measurements of 'H NMR spin-lattice relaxation times T , , T , , and the second moment M, were measured over t h e s a m e temperature range. These results showed that the cationic axial reorientation mainly contributes to 'H T , around room temperature, while the cationic self-diffusion plays an important role in t h e high-temperature range near T , . AC electrical conductivity measurements on single crystals revealed that ionic conduction takes place in t h e 2D layers of the room-temperature phase (rotator phase) which have a lamellartype double-layer structure. The observed T , and T l p data were explained well by applying the theory of 20 diffusion by MacGillivray and Sholl in the low vacancy concentration limit. The average jump times for the

Pyrrolidinium Imides: A New Family of Molten Salts and Conductive Plastic Crystal Phases

“…Conduction in Plastic Crystals. Much of this phase transition and conductive behavior below the melting point is reminiscent of the observations of Ikeda and co-workers [17][18][19][20][21] in their investigations of plastic crystal behavior in ammonium compounds and also of Cooper and Angell 22 in their study of plastic crystal behavior in a methoxyethyl dimethyl ethylammonium compound. These groups have described the properties of a number of tetraalkylammonium and dialkylammonium compounds with anions such as the halides, Cl -, Br -, BF 4 -, I -, and SCN -.…”

Conduction in ionic organic plastic crystals: The role of defects

“…This indicates that defects big enough to accommodate a cation and an anion are required for conduction, and that the rates of cation and anion diffusion are correlated. The correlation between the cation and anion diffusions has also been observed in many ammonium plastic crystals through NMR [17,25,26]. A possible explanation is a Schottky mechanism in phase III in which an ion hopping into a vacancy causes a counter-charged ion to hop into a vacancy in the vicinity to maintain local charge neutrality.…”

Structure and dynamics of the plastic crystal tetramethylammonium dicyanamide—a molecular dynamics study☆

“…Other organic based materials with multiple phase transitions and rotator phases include families of quaternary ammoniumcations, imidazolium-cations and pyrrolidinium-cations [9][10][11][12][13][14]. Organic ionic plastic crystals are closely related to ionic liquids (ILs); most of the cation families that give ILs also give plastic crystals.…”