Kinetic aspects of the thermal treatment of acid crystallohydrate, MgHPO<inf>4</inf>·-3H<inf>2</inf>O. part 1. changes in the IR spectra and proton delocalization

Abstract

Changes in the IR spectra of acid magnesium phosphate trihydrate heated to progressively higher temperatures point to increased proton mobility. A strong band, of complex structure, in the region of OH stretching vibrations is convoluted. Components of this band are supposed to be due to vibrations of different hydrogen bonded hydroxyl groups. From the changes of relative band intensities with temperature, using the Boltzmann equation, the activation energy is calculated and possible mechanism of proton delocalization discussed. It has been found that proton delocalization is a complex process which includes the following steps: dissociation of hydrogen bond, proton tunnelling effect and orientation of acceptor sites. © 1987.