Influence of the lead difluoride on ion mobility and thermal behavior of glasses in the TeO2–PbO·P2O5–PbF2 system according to NMR and DTA data

• New tellurite glasses TeO2–PbO·P2O5–PbF2:zMF3 (M = Er, Eu, Nd) were obtained.
• Characteristic temperatures Tg, Tx, and Tc decrease with increasing of PbF2 content.
• Fluoride sublattice ion motions are reorientations of fluorine-containing groups.
• An increase in the RE fluoride content promotes the glass microcrystallization.
• Transparent glass-ceramic samples were obtained by heat treatment.

New glasses doped with the Er3 +, Nd3 +, and Eu3 + ions were synthesized in the oxyfluoride system (100 − х − у)TeO2–хPbO·P2O5–уPbF2:zMF3 (x = 42.5–30 mol%, y = 5–30 mol%, z = 0.5–3.0 mol%, M = Er; z = 0.5 mol%, M = Eu, Nd) and studied by the 19F and 207Pb NMR, 31P MAS NMR, XRD and DTA. It was found that an increase in the PbF2 content causes a decrease in the temperatures of glass transition Tg and crystallization Tc. The glass doping with erbium fluoride in an amount up to 3.0 mol% at the constant PbF2 content has no effect virtually on values of the characteristic temperatures. According to the 19F NMR data, a possibility of local motion activation in the fluoride sublattice is determined by the lead fluoride content in the glass composition. There is no diffusion mobility in the fluoride sublattice of the considered glasses in the entire studied temperature range up to 570 K. The temperature range of 450–570 K is transitive, in which there are observed various reorientations of the fluorine-containing groups. According to the 31P NMR spectrum data at the magic angle (31P MAS NMR), there is a symmetric environment of PO4 structures in the glass.