Precipitation-induced healing of Nb2O5

Precipitation-induced stimulated-healing of Nb2O5 was carried out through the extrinsic addition of silver oxide nanoscale elemental inclusions to form ternary oxides at the crack site. Nb2O5 cylindrical pellets, 13 mm in diameter and 10 mm in length, were produced from powders using a cold isostatic press. The pellets were subsequently sintered at 1100 °C. A scratch was created in the sintered Nb2O5 pellets and was subsequently filled with Ag2O. The pellets were annealed to stimulate the self-healing process. X-ray diffraction was used to explore the evolution of phases, chemical compositions, and structural properties of the sintered samples before and after the stimulated-healing process. Energy dispersive X-ray spectroscopy revealed the elemental composition in the healed region. The on-site composition of the healed sample was determined by Raman spectroscopy and was compared to the spectrum outside of the scratch. Raman spectroscopy confirmed that precipitation proceeded via the following chemical reaction which was facilitated at elevated temperature: Nb2O5 + Ag2O → 2AgNbO3. In addition, a 3D reconstructed stylus profilometry image of the crack region confirmed that healing occurred. Healing by recovering 89% of the original material strength was confirmed using the three-point bend test.