• Dr. Ranjan Prasad
• Dr. Sebilal Sebak

The structure of several network-forming liquids and glasses is considered, where a focus is placed on the detailed information that is made available by using the method of neutron diffraction with isotope substitution (NDIS). In the case of binary network glass-forming materials with the MX2 stoichiometry (e.g. GeO2, GeSe2, ZnCl2), two different length scales at distances greater than the nearest-neighbour distance manifest themselves by peaks in the measured diffraction patterns. The network properties are influenced by a competition between the ordering on these “intermediate” and “extended” length scales, which can be manipulated by changing the chemical identity of the atomic constituents or by varying state parameters such as the temperature and pressure. The extended-range ordering, which describes the decay of the pair-correlation functions at large-r, can be represented by making a pole analysis of the Ornstein–Zernike equations, an approach that can also be used to describe the large-r behaviour of the pair-correlation functions for liquid and amorphous metals where packing constraints are important. The first applications are then described of the NDIS method to measure the detailed structure of aerodynamically-levitated laser-heated droplets of “fragile” glass-forming liquid oxides (CaAl2O4 and CaSiO3) at high-temperatures (∼2000 K) and the structure of a “strong” network-forming glass (GeO2) under pressures ranging from ambient to ∼8 GPa. The high-temperature experiments show structural changes on multiple length scales when the oxides are vitrified. The high-pressure experiment offers insight into the density-driven mechanisms of network collapse in GeO2 glass, and parallels are drawn with the high-pressure behaviour of silica glass.

Liquid and Amorphous Metals; Network Properties; Temperature and Pressure

"Definition of Partial Structure Factor", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.7, Issue 11, page no.185-189, November-2020, Available :http://www.jetir.org/papers/JETIR2011322.pdf

"Definition of Partial Structure Factor", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.7, Issue 11, page no. pp185-189, November-2020, Available at : http://www.jetir.org/papers/JETIR2011322.pdf