Subsolidus phase equilibria in the CaO-poor part of the RuO2–CaO–SiO2 system

During firing the conductive phase based on CaRuO3 in lead-free thick-film resistors decomposes, presumably due to interactions with the silica-rich glass phase. Subsolidus equilibria in the CaO-poor part of the RuO2–CaO–SiO2 diagram were studied with the aim of investigating possible interactions between the conductive phase and silica-rich glasses in thick-film resistors. The tie lines are between CaRuO3 and CaSiO3, and between RuO2 and CaSiO3. This indicates that the calcium ruthenate is not stable in the presence of the silica-rich glass phase.