[1][2] POIPCs are solid protic organic salts formed by proton transfer from a Brønsted acid to a Brønsted base and in essence are protic ionic liquids in the molten state, have found to be promising solid-state proton conductors for high temperature proton-exchange membrane fuel cells.
[3] X-ray diffraction patterns of plastic crystals are characterized by strong diffuse intensity in addition to the sharp Bragg peaks.
[1] In a powder pattern this intensity appears to resemble an amorphous background as one would expect for a liquid,[1] but for a single crystal the diffuse contribution reveals itself to be highly structured.
Recent advances in two-dimensional detection at synchrotron beam lines facilitate the study of such patterns via techniques such as small-angle X-ray scattering.
He found that organic substances having an entropy of fusion lower than approximately 17 J·K−1·mol−1 (~2R, where R is the molar gas constant) had peculiar properties.
Michils showed in 1948 that these organic compounds are easily deformed and accordingly named them plastic crystals (cristaux organiques plastiques).
[5] Some plastic crystals, like aminoborane, when subjected to mechanical stress, exhibit behavior similar to ductile metals such as lead, gold, silver, or copper.