Investigation of Bioglass-Electrode Interfaces after Thermal Poling

TL;DR

This study investigates the effects of thermal poling on bioglass-electrode interfaces, revealing interfacial layer formation, ion transport processes, and potential bioactivity enhancement through detailed electrochemical and microscopic analyses.

Contribution

It provides new insights into interfacial layer formation and ion dynamics in bioglasses during thermal poling, using combined electrochemical and microscopic techniques.

Findings

Interfacial layers form under electrodes during poling.

Na+ ions are involved in redox and transport processes.

Ca2+ ions remain immobile under poling conditions.

Abstract

Electrical and electrochemical processes in a bioactive soda-lime phosphosilicate glasses and in a bioabsorbable soda-lime phosphate glass during thermal poling were studied by means of thermally stimulated depolarization current measurements, ac impedance spectroscopy, and SEM/EDX analyses. The thermal poling was done by sputtering thin Pt electrode films onto the faces of the glass samples and by applying voltages up to 1 kV to the electrodes at temperatures up to 513 K. The poling leads to the formation of interfacial layers under the electrodes which are responsible for two depolarization current peaks and for one additional semicircle in a Nyquist plot of the ac impedance. The SEM/EDX profiles suggest that redox and transport processes of Na+ ions are responsible for the formation of the interfacial layers and that Ca2+ ions are immobile under the poling conditions. The sodium depletion layer under the anode leads to a negative surface charge of the glass samples which may enhance their bioactivity.