Thermal stability of crystalline phases in MnO-doped zinc borosilicate glasses

We have studied a relatively overlooked subset of the MnO-doped zinc borosilicate glass system with a goal of investigating the effects of MnO-doping on the thermal stability of crystalline phase formation in the system. A glass system of general composition 55ZnO–20B2O3–25SiO2 with added MnO dopant, which replaces Zn modifier locations with Mn, ratios of 0, 0.005, 0.01, and 0.015 MnO:ZnO were prepared, via batch melting at 1550 °C for 1.5 h. The glasses were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS). Thermal analysis, followed by detailed XRD and Rietveld structural refinement, revealed the formation of zinc borate (Zn4O(BO2)6), willemite (Zn2SiO4), and manganese zinc silicate ((ZnMn)SiO4) crystallites after heat-treatment at 875 °C for 4 h and zinc borate crystallites influenced by the borate anomaly in samples heated to ≈ 955 °C at a ramp rate of 10 °C/min and held for 4 h. Microstructure and elemental maps confirmed that the zinc borate had become an integral part of both glass and crystalline phases in the resulting glass–ceramic samples. MnO-content influenced the formation of the boron-containing glass phase via the borate anomaly.