Subsolidus phase equilibria in the CaO-poor part of the RuO₂–CaO–V₂O₅ system

Excerpt

Thick-film resistor pastes consist basically of a conducting phase, a silica-rich, lead-borosilicate-based glass phase and an organic vehicle. The organic material is burned out between 300 and 400 °C during the high-temperature processing. The ratio between the conductive and glass phases roughly determines the specific resistivity of the resistor. In most modern thick-film resistor compositions the conductive phase is either ruthenium-oxide or electrically conducting pyrochlores; mainly lead or bismuth ruthenates [1‐4] with resistivities of 40 × 10⁻⁶, 150 × 10⁻⁶ and 270 × 10⁻⁶ Ω cm for RuO₂, Bi₂Ru₂O₇ and Pb₂Ru₂O_6.5, respectively [2, 5]. During the firing cycle the conductive phases of the resistor materials interact with the glass phase. The maximum firing temperature and time are typically 850 °C and 10 min, respectively. …