Small-angle X-ray scattering characterization of porous glasses

Small-angle X-ray scattering has been used to examine porous glasses. The experiment and analysis of the extracted data are described with specific concern for the quantitative characterization of the pore structure. The techniques used are illustrated by the results obtained from two selected porous glasses. Small-angle X-ray scattering data of two series of novel porous glass systems are presented and discussed

Small-angle X-ray scattering study of the growth kinetics of CuCl nanocrystals in NaCl

The precipitation of CuCl nanocrystals in a NaCl matrix has been studied by time-resolved small-angle X-ray scattering. The experimental results suggest that the nucleation process is accelerated by lattice defects of the matrix remaining in the NaCl lattice after the dissolution of previous nanocrystals at high temperature. The evolution of structural parameters calculated from the scattering curves, such as volume fraction, mean radius and particle number density of the nanocrystals, is discussed in terms of a classical phase separation process but with specific concern for the effect of elastic strains. It was found that Ostwald ripening is effective during the whole period of observation. The effect of elastic strains results in an increase of the critical radius and a decrease of the coarsening rate. The results of the scattering experiments confirm the miscibility gap data determined by exciton spectroscopy

Non-uniform distribution of small-scale inhomogeneities in melt-spun Fe80B20 ribbons

Amorphous melt-spun Fe80B20 ribbons have been investigated by small-angle X-ray scattering to extract additional information on small-scale inhomogeneities observed in transition metal-metalloid glasses by several authors. Our experiments have shown that the scattering heterogeneities of electron density, the dimensions of which amount to about 1 nm, exist only in regions adjacent to the edges of the ribbons studied. This emergence suggests that the scattering items cannot be identified with intrinsic features of the amorphous state of the Fe80B20 alloy. There are several reasons to assume that the scattering heterogeneities are attributable to devitrification processes running down in the regions adjacent to the edges of the ribbons where possibly the quenching velocity is reduced

The intermediate range order of metaphosphate glasses by X-ray diffraction

Metaphosphate glasses containing the metal ions Me=Li, Na, K, Ag, Mg, Ca, Co, Zn, Sr, Cd, Ba, Pb, Al, La have been studied by X-ray diffraction. Information on the intermediate range structure of the glasses is extracted from the main peak in the structure factors, S(s), possibly occurring prepeaks, scattering effects in the small angle range and the zero-angle scattering intensity. Most of the glasses studied develop a quasi-periodic superstructure in the intermediate range scale indicated by a first diffraction peak in S(s). The constitution of the superstructure is based on different principles governed by the type of metal ion present in the glass. A mixed oxide effect was found to exist for ternary metaphosphate glasses of the Na2O–BaO–P2O5 system but did not exist for the Na2O–K2O–P2O5 system. Small angle scattering effects are observed only in the S(s) functions of the Mg(PO3)2 glasses. The features of these scattering effects depend on the cooling conditions of the glass melt, and their appearance is correlated with the crystallization behaviour of the glasses