Phase formation and reactions in the Bi₂O₃–ZnO–Nb₂O₅–Ag pyrochlore system

Mixed-phase compositions in the Bi₂O₃–ZnO–Nb₂O₅ pyrochlore system have been previously identified as potential low-fire dielectric composites for high-frequency multilayer devices. However, there has been a problem with the ability to co-process this material with silver. It was found that an intermediate BiNbO₄ phase that occurs during calcination can interact with silver during co-sintering, forming a deleterious phase. Processing routes to control the presence of remanent BiNbO₄ were investigated, such as ZnO stoichiometric adjustment, low partial pressure of oxygen sintering atmosphere, and specific temperature-time dwells.