University of Pardubice Faculty of Chemical Technology

University

Employees
|
Students
Česky

Publication detail

Silver borophosphate glasses modified with tungsten and molybdenum trioxide

Authors: Hostinský Tomáš | Mošner Petr | Koudelka Ladislav

Year: 2023

Type of publication: ostatní - přednáška nebo poster

Page from-to: nestránkováno

Titles:

Language	Name	Abstract	Keywords
eng	Silver borophosphate glasses modified with tungsten and molybdenum trioxide	This contribution deals with study of mixed glass former effect (MGFE) and its effects in two series of borophosphate glasses of 40Ag2O-20MO3-(40-x)P2O5-xB2O3 (where M = W, Mo) in a composition range of x = 0-30 mol% B2O3. Basic physico-chemical properties were determined, and thermal properties studied by differential thermal analysis and thermomechanical analysis. The glass structure was investigated using Raman spectroscopy and both 1D and 2D 11B and 31P MAS NMR spectroscopy. Behavior and oxidation states of tungsten and molybdenum throughout the series was investigated using EPR spectroscopy. The electrical properties of the glasses were obtained by using impedance spectroscopy. In both series, glass transition temperature, Tg, increases in range of 0-10 mol% B2O3, further additions results in slight decline of Tg values. Results from impedance spectroscopy reveals non-linear increase in DC conductivity which can be attributed to MGFE and therefore changes in the structure of the glass network. The second possible explanation of the development in DC conductivity can be attributed to the presence of reduced forms of W and Mo which can affect the resulting conductivity by the polaron hopping phenomenon. This phenomenon has already been studied and confirmed on glasses of similar systems.1 Structure of the glasses was probed with multiple MAS NMR experiments. To get first information about the glass network, standard 1D experiments of 11B and 31P nuclei were performed. From obtained 31P MAS NMR spectra is visible the transformation of the dominant phosphate structural units in the direction of Q2–>Q0 with B2O3 additions, and thus the shortening of the phosphate chains. Development in 11B MAS NMR spectra reveals presence of both BO4 and BO3 structural units through the series. Interconnections between phosphate and borate species was further studied by multiple 2D correlation techniques. Namely 2D 31P INADEQUATE sequence was used to probe direct trough bond conne