Chemical Compatibility between Silver Electrodes and Low‐Firing Binary‐Oxide Compounds: Conceptual Study

The chemical compatibility of silver electrodes and low‐firing ceramics has been considered, in terms of the existence of a tie line between silver (and/or Ag 2 O) and the binary oxide compound in the corresponding ternary phase diagram. The probability of the existence of the tie line is related to the conditions in the subordinated silver‐based isothermal binary systems. Greater probabilities have been calculated for the systems with fewer silver‐based binary compounds. Based on the concepts that have been developed, several silver‐based isothermal binary systems have been investigated to identify the oxides suitable for the development of low‐temperature cofired ceramics. The developed concept has been tested by investigating the phase relations in the Bi 2 O 3 –Nb 2 O 5 and Bi 2 O 3 –V 2 O 5 ternary systems with silver. X‐ray and microstructural investigations of bismuth niobates and bismuth vanadates reveal that, as a result of the inertness of Bi 2 O 3 and the reactivity of Nb 2 O 5 and V 2 O 5 toward silver, compounds that are rich in niobium or vanadium react with silver to form ternary Nb/V‐Bi‐Ag oxide compounds, whereas for compounds that are rich in bismuth, tie lines to silver and Ag 2 O do exist.