Mass spectrometric evidencing on modified random network microstructure and medium range order in silicate glasses

Abstract

Mass spectrometric analysis of newly formed surface on breaking a sodium borosilicate glass bar revealed its significant enrichment with sodium, slight higher content of boron and depletion in Mg, Ca, Al, Ti and Mo compared the initial glass surface. This conforms to recent low energy ion observation of Almeida et al. and evidences on modified random network microstructure and medium range order in silicate glasses. The glass investigated was a borosilicate glass (wt.%) 48.2·SiO2 7.5·B2O3 2.5∙Al2O3 1.5∙Fe2O3 15.5∙CaO 16.1∙Na2O 8.7∙Misc which is a simulant of high-sodium nuclear waste glass K-26. The glass bar after annealing was broken openly in air using a hammer. Laser Ablation System New Wave UP 213 coupled with laser ablation-inductively coupled plasma-mass spectrometry ICP-MS 4500 system was used for analyses. The mass spectrometric analysis comprised the elements: 95Mo, 11B, 23Na, 24Mg, 27Al, 30Si, 43Ca, and 47Ti. The laser ablation was taken samples from the freshly formed surface as well as from its initial surface of glass bars. The relative changes of average normalised mass spectrometric signal intensities on formation of a new glass surface were as follows: 1.14 for 11B, 1.35 for 23Na, 0.8 for 24Mg, 0.83 for 27Al, 0.75 for 43Ca. 0.76 for 47Ti and 0.77 for 95Mo. These data evidence on modified random network microstructure and show that the glass breaks along weaker ionic percolating channels formed by alkalis so resulting in alkali enriched surfaces. The results obtained may be useful for configuron percolation theory of glass transition, interpretation and controlling glass corrosion, as well as for potential applications in medicine and biology.