Abstract
Low-frequency Raman spectra of the sodium borate glasses with Na2O content ranging from 0 to 30 mol% were measured and analyzed from the point of view of their structure in the intermediate range order. Our results show that there is a simple linear correlation between correlation length, lc, and an average size, <R>, of the area of ordered arrangement of atoms, obtained via the distribution of the (super)structural units and their representative size. Six types of the areas of ordered arrangement of atoms were determined, being related to the presence of the B3O3⌀3 boroxol rings, B3O3⌀4- triborate rings, B5O6⌀4- pentaborate groups, B8O10⌀62- tetraborate groups, B4O5⌀42- diborate groups, and B3O63- cyclic metaborate anions in the sodium borate glasses. It was shown that the size of the areas of ordered arrangement of atoms can be determined from the simple geometric analysis of the crystallographic data on the superstructural units.
Highlights
It is accepted to distinguish two hierarchical structural levels in the structure of borate glasses
Five basic structural units are usually distinguished in borates according to the coordination number of the boron atoms and to the number of bridging oxygen atoms (BO) and NBOs belonging to the given boron atom: B⌀3 symmetric triangle (⌀ is BO), [B⌀4]− borate tetrahedron, B⌀2O− metaborate triangle, B⌀O22− pyroborate unit, and BO33− orthoborate anion
We have found that the linear size of the diborate group along X-axis, RXD, is equal to ∼5.7 A, based on the data presented in Table 7 in ref
Summary
It is accepted to distinguish two hierarchical structural levels in the structure of borate glasses. Five basic structural units are usually distinguished in borates according to the coordination number of the boron atoms and to the number of BOs and NBOs belonging to the given boron atom: B⌀3 symmetric triangle (⌀ is BO), [B⌀4]− borate tetrahedron, B⌀2O− metaborate triangle, B⌀O22− pyroborate unit, and BO33− orthoborate anion. All of these basic structural units can be identified experimentally, e.g., by NMR or vibrational spectroscopies, and to date, the local structure of borate glasses is well studied both qualitatively and quantitatively.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
