The Effect of Tetraphenylphosphonium Chloride on Phase Behavior and Nanoscale Structures in a Mixture of $\text{D}_{2}\text{O}$ and 3-Methylpyridine

Abstract

The effects of adding an “inversely antagonistic” salt, tetraphenylphosphonium chloride ($\text{PPh}_{4}\text{Cl}$), to a binary mixture of deuterated water and 3-methylpyridine were investigated by visual inspection and small-angle neutron scattering. With increasing salt concentration, the two-phase region shrinks and a charge density wave structure is induced, as in the case of adding a “normally antagonistic” salt, sodium tetraphenylborate ($\text{NaBPh}_{4}$), to the binary mixture. The concentration range of the periodic structure is narrower than that in the case of adding $\text{NaBPh}_{4}$, and no ordered lamellar structure is observed in the present study.