Ionic Conductivity and Phase Diagram of the CuBr ‐ AgI System

Abstract

The ionic conductivity characteristics and the phase diagram of the system have been determined. Extensive solid‐solution ranges exist for . A body‐centered tetragonal (δ) modification of exists from below ∼170°C. A eutectic is present at and 306°C. Conductivity (both ac and dc) and mass transport measurements on polycrystalline hot‐pressed specimens indicate that both Cu+and Ag+ ions are transported during charge flow. A study of the phase diagram indicated that an examination of the conductivity properties of three compositions would characterize the system. Generally, the conductivity of each composition increased from ∼10−5 to ∼10−1 (Ω‐cm)−1over the temperature range from about 25° to 300°C. Compositions with exhibit distinct transitions to the highly conductive state at ∼160°C, similar to that observed for . However, a well‐defined transition is not observed for . The conductivity changes with composition and temperature are consistent with the structural changes indicated in the phase diagram. The electronic contribution to the conductivity is <1%.