On Polyamorphism of Triphenyl Phosphite

Abstract

We investigated the glass former triphenyl phosphite by calorimetry, Brillouin scattering, and dielectric and nuclear magnetic resonance spectroscopy. Time-resolved experiments demonstrate the conversion between three distinctly different phases, namely, the supercooled liquid, a recently discovered apparently amorphous phase (glacial phase), and the crystalline phase. The temperature dependencies of the properties provided by the different methods are compared. We find significant molecular motion in the glacial phase. From this we hypothesize that the glacial phase is a different highly viscous liquid or a solid phase with some kind of cooperative relaxation.

Size dependence of the Raman spectra in an amorphous–nanocrystalline mixed phase: the glacial state of triphenyl phosphite

“…4 -6 The strong relaxation process evidenced by means of both dielectric and NMR measurements 4,5 is not fully interpreted in the context of a description of the glacial state as a strong metastable liquid, because of the unphysically small exponential prefactor obtained by fitting relaxation times with an Arrhenius behavior. 4 The reorientational correlation function obtained in the glacial state 5 can be considered as atypical of a crystal environment, but is not necessarily in opposition to the description of the glacial state as composed of very small crystallized clusters (¾30Å) embedded in the supercooled liquid matrix. Moreover, the unusual broadened relaxation contribution observed in a very low-wavenumber range, previously considered to be the relaxation spectrum of the glacial state, could be tentatively interpreted as slow motions of very small crystallized clusters in the nontransformed metastable liquid.…”

“…4,5 The most original feature revealed by the study of the internal Raman spectrum of the glacial state is the substantial sharpening of internal modes, which are a signature of crystallized domains, when the glacial state is prepared above 222 K. This observation is highly suggestive of a description of the glacial state, above 222 K, in terms of microcrystallized domains rather than in a nanostructure. This is confirmed by the quasi-absence of the intensity I a scattered from the amorphous volume near 1160 cm 1 in the spectrum of the glacial state prepared at 226 K, that is suggestive of a quasi-fully crystallized state.…”

“…4,9 Taking account the effect of temperature upon low-wavenumber Raman intensities, Raman spectra recorded at T a > 214 K were replotted using…”

On the number of amorphous phases in n-butanol

“…After fast cooling, TPP easily gives glass (T g = 205 K [9]). If the sample of the overcooled TPP liquid is annealed at T > T g in the region of 213-225 K, a change in the sample is observed.…”

“…At present, this is, probably, the only compound, which has no threedimensional network of bonds for which the existence of two solid amorphous phases is assumed. The ÔglacialÕ phase of TPP has been studied actively by various methods [9][10][11][12][13][14][15][16][17]. Despite all attempts, there is no unambiguous description of the structure of the new state.…”