Effect of Silver Doping on the Physical and Electrical Properties of PLZT Ceramics

Additions of small amounts of silver to a PLZT dielectric with emphasis on the 88/12/70/30, Pb/La/Zr/Ti, composition were investigated. It was found that a few mole percent of Ag¹⁺ could be incorporated into the PLZT lattice as a large acceptor cation and that it tended to reduce the lead vacancies, which are normally generated by the substitution of La³⁺ in the PLZT dielectric. The addition, up to 2 mol% of silver, decreased the 25°C dielectric constant from 2300 to 1700. However, the temperature coefficient of capacitance was improved to ±5% between -55° and +125°C, and the dissipation factor was reduced from 1.5 to 0.5%. Although the gravimetrically measured lead loss appeared to depend on the relative vapor pressure of lead oxide during sintering, the compensation mechanism of Ag¹⁺ was not affected.