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Borosilicate glass; leaching; ISG; FTIR; DTA; luminescence.

Pellet leaching and associated thermal and structural changes of sodium borosilicate (NBS) glass, used for the immobilization of high-level radioactive liquid waste, subjected to aggressive test conditions have been compared with international simple glass (ISG) subjected to the same leaching conditions. The crystalline phase getting separated out from NBS glass is found to be different for pellets and powder leaching experiments and this has been explained based on the difference in the extent of leaching occurring with glass samples in the two experiments. Based on Fourier transform infrared studies, it is inferred that, unlike in the ISG sample, Si–O–Si/B structural units become more ordered with the leaching in the case of NBS glass, and this is attributed to the partial network destruction occurring with NBS glass and crystallization of the SiO₂ phase from the glass matrix. Both the NBS glass and ISG sample show L-centre emission and the emission intensity remained unaffected with leaching, confirming that the local environment around non-bridging oxygen atoms in the NBS glass and ISG sample are unaffected and leaching occurs through network dissolution.

VIDYA S THORAT^{1 2} R K MISHRA¹ V SUDARSAN³ AMAR KUMAR¹ A K TYAGI^{2 3} C P KAUSHIK^{1 2}

1. Waste Management Division, Bhabha Atomic Research Centre, Mumbai 400085, India
2. Homi Bhabha National Institute, Anushakti Nagar, Mumbai 400094, India
3. Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India

Published

October 2019

Manuscript received

29 January 2019

Accepted

26 March 2019

Final version published online

28 June 2019