Surface Morphology of P2O5-CaO-Nb2O5-Na2O Glass-Ceramics after Acid Treatment: SEM and XRD Study
Modification of surface morphology and composition of niobophosphate glass and glass-ceramic in the system P2O5-CaO-Nb2O5-Na2O was investigated. Amorphous, partly crystalline and crystalline samples were prepared in shape of pellet with diameter 10 mm. Samples were treated in 1 and 5 days in citric acid at 37°C and 3h in boiling HCl. Surface morphology before and after treatment was investigated by scanning electron microscopy (SEM), phase composition by X-ray powder diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). Glass sample was smooth, after treatment in citric acid it had cracks and pit-holes on the surface. Partly crystalline sample was smooth and contained inclusions of crystalline Ca3(PO4)2 and Ca2P2O7. Platy crystals of Ca3(PO4)2 dissolved first, than bulky Ca2P2O7. Crystalline samples contained Na4Nb8P4O32 and calcium phosphate phases; surface was rough before and after treatment. EDX showed that amount of phosphorous is proportional to amount of calcium and inversely proportional to amount of sodium and niobium in glass-ceramic samples.
Eyup Sabri Kayali, Gultekin Goller and Ipek Akin
A. Stunda et al., "Surface Morphology of P2O5-CaO-Nb2O5-Na2O Glass-Ceramics after Acid Treatment: SEM and XRD Study", Key Engineering Materials, Vols. 493-494, pp. 61-67, 2012