Synthesis and structural characterizations of polyamorphous materials

The structure of densied GeO₂ and a mechanism for densification is discussed in Chapter 1. Information about the partial structure factors of normal and permanently densified GeO₂ glass has been obtained from neutron and x-ray diffraction measurements. Densification causes a reduction in the length scale of the intermediate range order (IRO). The difference structure factors show the greatest effects when the Ge-Ge correlations are eliminated and least when O-O correlations are eliminated. This implies that the reduced length scale results from a decrease in the next-nearest neighbor Ge-O and O-O distance caused by a rotation about the Ge-O-Ge bonds and a distortion of the GeO₄ tetrahedra.; Chapter 2 reports on the structural quantum isotope effects in amorphous beryllium hydride. The intermediate range structure of beryllium deuteride is found to vary largely from beryllium hydride. This effect has a great impact for development of the quantum part of the interatomic potential in a system that can easily be modeled.; In Chapter 3, small angle neutron scattering is used to explore the clustering of triphenyl phosphite. Glacial phase clustering and growth in triphenyl phosphite (TPP) is observed in the temperature interval of 210 K to 214 K by small angle neutron scattering. Presented are radii, volume fraction and polydispersity of clusters of glacial phase surrounded by supercooled liquid. The data can be interpreted in a four-step model of cluster formation rapid nucleation, agglomeration, and saturation.; In Chapter 4, the glassforming properties of triphenyl phosphite are reviewed and the properties of tris(phenylthio)phosphine and tris(phenylseleno)phosphine are presented. It was found that the tris(phenylthio)phosphine and tris(phenylseleno)phosphine do not exhibit the glacial phase that has been found in triphenyl phosphite. The known crystal structures and ab initio calculations are used to understand the nature of a glacial phase.; Chapter 5 discusses the design and implimentation of a new undergraduate physical chemistry laboratory course. New experiments were developed and combined with classical physical chemistry experiments to develop a laboratory course that is interdisciplinary and more modern.