Eur. Phys. J. Plus (2025) 140: 892
https://doi.org/10.1140/epjp/s13360-025-06706-1

Regular Article

Correlating the structure and dynamics of borophosphate glasses: molecular dynamics approach

¹ Laboratory of Advanced Materials and Applications (LM2A), Faculty of Sciences Dhar El Mahraz, University of Sidi Mohamed Ben Abdellah, 30003, Fez-Sais, Morocco
² Laboratory of Physical-Chemistry, Materials and Catalysis (LCPMC), Faculty of Sciences Ben M’sik, University Hassan II of Casablanca, 20670, Casablanca, Morocco
³ Laboratory of Inorganic Materials for Sustainable Energy Technologies (LIMSET), Mohammed VI Polytechnic University, Ben Guerir, Morocco

^a mohamed.naji3@usmba.ac.ma

Received: 21 January 2025
Accepted: 31 July 2025
Published online: 16 September 2025

Abstract

Employing molecular dynamics simulations, we investigate the structural evolution in sodium borophosphate glasses ($35{\text{Na}}_2\text{O}-65[x{\text{B}}_2{\text{O}}_3-(1-x){\text{P}}_2{\text{O}}_5]$). Our simulations reveal that boron coordination shifts from predominantly four-fold (${\text{B}}^{[4]}$) to mixed three/four-fold ($B^{[3]}/B^{[4]}$) configurations with increasing boron content. The dominant $P-O-B^{[4]}$ linkages facilitate homogeneous network integration at intermediate compositions ($x=0.4-0.5$), while higher boron concentrations promote $B^{[4]}-O-B^{[3]}$ connectivity and polymerization. Crucially, radial distribution functions and coordination analysis demonstrate that charge-compensating ${\text{Na}}^{+}$ ions exhibit delocalized bonding environments around ${\text{B}}^{[4]}$ units, with $Na-O$ coordination increasing from 5.4 ($x=0$) to 7.9 ($x=1$). This structural reorganization reduces non-bridging oxygens and creates new hoping site that enhance ionic conductivity. Our atomistic insights establish a direct correlation between $P-O-B$ connectivity, sodium-ion delocalization, and macroscopic ion transport, providing a foundation for designing optimized borophosphate glass electrolytes.