University of PardubiceFaculty of Chemical Technology

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Effect of titanium dioxide on thermal behavior and properties of niobate-phosphate glasses

Authors: Mošner Petr | Koudelka Ladislav | Kalenda Petr

Year: 2020

Type of publication: ostatní - přednáška nebo poster

Page from-to: nestránkováno

Titles:

Language	Name	Abstract	Keywords
eng	Effect of titanium dioxide on thermal behavior and properties of niobate-phosphate glasses	TiO2 containing phosphate-niobate glasses were prepared in the compositional series 40Na2O-40P2O5-20Nb2O5+xTiO2 within the range of x=0-36, using conventional melt quenching technique, when the melt (1200-1400 oC) was poured into a tempered graphite mould. Glasses were characterized by the measurements of density, molar volume and chemical durability. The structure of glasses was investigated by Raman spectroscopy, their thermal properties were studied by DSC, thermodilatometry and hot stage microscopy. Crystalline phases were identified by X-ray powder diffraction analysis. Raman spectra showed that the structure of starting 40Na2O-40P2O5-20Nb2O5 glass is formed mainly by metaphosphate (Q2) and diphosphate (Q1) structural units interconnected by P−O−P bonds. Nb2O5 is incorporated in the structural network in the form of NbO6 octahedral units. Introducing and gradually increasing of TiO2 content causes a slow depolymerization of the phosphate structural network and the development of probably TiO6 octahedral units in the local structure of the glass matrix. Glasses show the almost linear increase in the density, whereas molar volume steeply decreases with increasing TiO2 content. The highest values of glass transition temperature, dilatometric softening temperature, crystallization temperature and flow temperature were obtained for the glass containing 28 mol% TiO2. This glass revealed also the highest chemical durability against water attract and on the contrary the lowest thermal expansion. The DSC curves indicated that all glasses crystallize on heating.	phosphate glasses; Nb2O5; TiO2; properties; thermal behavior