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Phosphate glass; microhardness; FTIR; MAS NMR.

Phosphate glasses having composition, 40Na₂O–10BaO–𝑥B₂O₃–(50–𝑥)P₂O₅, where 𝑥 = 0–20 mol% were prepared using conventional melt quench technique. Density of these glasses was measured using Archimedes principle. Microhardness (MH) was measured by Vicker’s indentation technique. Structural studies were carried out using IR spectroscopy and ³¹P and ¹¹B MAS NMR. Density was found to vary between 2.62 and 2.77 g/cc. MH was found to increase with the increase in boron content. ³¹P MAS NMR spectra showed the presence of middle 𝑄² groups and end 𝑄¹ and 𝑄⁰ groups with P–O–B linkages. FTIR studies showed the presence of BO₃ and BO₄ structural units along with the depolymerization of phosphate chains in conformity with ³¹P MAS NMR. ¹¹B NMR spectra showed increase in BO₄ structural units with increasing boron content. The increase in MH with B₂O₃ content is due to the increase of P–O–B linkages and BO₄ structural units as observed from MAS NMR studies resulting in a more rigid borophosphate glass networks.

K V Shah¹ M Goswami¹ M N Deo² A Sarkar¹ S Manikandan¹ V K Shrikhande¹ G P Kothiyal¹

1. Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
2. Synchrotron Radiation Section, Bhabha Atomic Research Centre, Mumbai 400 085, India

Published

February 2006

Manuscript received

18 July 2005

Manuscript revised

26 September 2005