Effect of P2O5 on the structure and phase separation of sodium borosilicate glasses

• Published in: Hanʼguk Seramik Hakhoe chi 2024, 61(2), 411, pp.250-257
• Main Authors: Hwang, MinSeong, Chung, Jaeyeop
• Format: Article
• Language: English
• Subjects: Ceramics; Chemistry and Materials Science; Composites; Glass; Materials Science; Natural Materials; Original Article; 재료공학
• ISSN: 1229-7801; 2234-0491; 2334-0491
• DOI: 10.1007/s43207-023-00344-y

The effect of P 2 O 5 as an additives that promote the phase separation and distribution of phosphorus in sodium borosilicate glass was investigated. We prepared various NBS1 glasses: (100- x )(0.17Na 2 O–0.29B 2 O 3 –0.54SiO 2 )– x P 2 O 5 ( x  = 0, 3, 5, 7, and 10 wt%) and an NBS2P7 glass: 93(0.22Na 2 O–0.24B 2 O 3 –0.54SiO 2 )–7P 2 O 5 (wt%). Phase separation was confirmed by scanning electron microscope (SEM) and inductively coupled plasma-atomic emission spectrometry (ICP-AES). To understand the phase separation phenomenon, 31 P, 11 B and 29 Si magic angle spinning nuclear magnetic resonance (MAS-NMR) analyses were performed. It was confirmed that phase separation was induced when the P 2 O 5 content was great than 5 wt% in NBS1 glasses, together with a change in the mechanism of phase separation from droplet-type to spinodal-type with increasing P 2 O 5 concentration. The phosphorus incorporated into the borate-rich phase and formed borophosphate units after phase separation. Additionally, the fraction of [BO 4 ] units decreased with increasing P 2 O 5 concentration. This phenomenon is expected to strongly influence the phase separation of sodium borosilicate glasses. In the NBS2P7 glass, no phase separation was observed owing to the high contents of P 2 O 7 4− and PO 4 3− units. These units were released from the borosilicate matrices to form Na 4 P 2 O 7 crystalline phases.