Topography and microstructure of phosphate-iron glasses containing niobium and titanium

The topography and microstructure of phosphate-iron glasses containing niobium and titanium were investigated by the means of X-ray diffraction (XRD), scanning electron microscopy (SEM). Glass samples of the composition of 35P2O5-30Fe2O3-(35-x)Nb2O5-xTiO2 where x= 0; 7.5 and 15 (in %mol) were prepared by the conventional melt quenching technique. Appropriate amounts of reagents ((NH4)2HPO4 (≥99.9%, POCH), Fe2O3 (≥99.9%, POCH), Nb2O5 (≥99.9%, PLUKA AG) and TiO2 (≥99.9%, anatase and rutile mixed, PROLABO)) were thoroughly mixed in an agate mortar and put on electric stove in temperature of 573K in order to carry out the decomposition process of (NH4)2HPO4. Next powders were melted in porcelain crucibles at 1573 K for 1-2 h, depending on glass composition. The melts were poured on preheated (to 573 K) brass plate and pressed by another plate to obtain flat circular samples (dimensions: 1-2 mm thick, 20-30 mm in diameter). The obtained pellets were annealed at 673 K for 1 h and cooled with furnace. The structure has been studied by the X-ray diffraction method with the use of a Philips X 'Pert Pro MPD system with the CuKα radiation. The XRD measurements were carried out on powder samples at room temperature. Scanning Electron Microscope FEI Quanta FEG 250 using 30kV beam accelerating voltage with SE-ETD detector (secondary electron - Everhart-Thornley detector) working in high vacuum mode (pressure 10-4 Pa) was used to observe the structure of the uncoated glasses.
Detailed information can be found in: doi: 10.1016/j.proeng.2014.12.488