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Apparent Polyamorphism as Encountered in the Molecular Fluid, Triphenylphosphite. ^* Daniel Kivelson, ⁺ Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095

As we understand it, polyamorphism involves the existence in a one-component system of two amorphous condensed phases, both of which are likely to be metastable relative to the crystal. It is often difficult to specify whether the two states are truly thermodynamically distinct amorphous condensed phases or whether they are dynamically sluggish different states of the same phase; in both cases we expect hysteresis. Unfortunately, the diffraction patterns have not always enabled us to determine whether the phases are truly amorphous, i.e., whether they lack all indications of long-range order. In considering the subtle conditions required to specify polyamorphism one must also ask how important it is to define phases so pedantically? We have studied in some depth what appears to be one of the most striking cases of polyamorphism, that of the supercooled liquid (or glass) and the distinctly different, apparently amorphous solid “glacial phase” of triphenylphosphite (which can exist above the glass transition temperature). Many unresolved questions remain, some, we believe, carrying over to other cases of apparent polyamorphism.

^*Supported by the National Science Foundation and the Research Corporation.

⁺A Collaborative effect with numerous coworkers.