The origin of hysteresis in the electrical behavior of RuO2-glass composite melts

•The glass composites show distinct electrical behavior depending on RuO2 content.•The hysteresis event is only observed for RuO2-contaning glasses.•The hysteresis behavior takes place mostly where the ionic conductivity is dominant.•A hypothesis that fulfill the observed characteristics of the hysteresis phenomenon is proposed The main goal of the present work is to unveil the nature of phenomena related to the so-called hysteresis response in the electrical conductivity of RuO2-glass composites melts. Therefore, a set of sodium-calcium borosilicate glasses with different RuO2 contents is synthesized and characterized by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. The electrical properties of these composites are assessed by impedance spectroscopy using low (glassy state) and high temperature (melt) measurements. Glass composites with RuO2 content lower than ~1% mol. present an ion-conducting behavior while samples with RuO2 content higher than ~1% mol. show a predominant metal-like conductivity. The hysteresis event is only observed for RuO2-containing glasses and gets more pronounced as the RuO2 concentration is increased. On the other hand, the hysteresis behavior seems to take place mostly where the ionic conductivity is dominant. Herein, a hypothesis that fulfills all the observed characteristics of this hysteresis phenomenon is proposed. [Display omitted]