Development of a lead‐free copper co‐fired BNT‐based piezoceramic sintered at low temperature

Abstract

Compatibility of Bi‐based piezoelectric ceramic and copper electrodes is demonstrated by co‐firing 0.88Bi1/2Na1/2TiO3–0.08Bi1/2K1/2TiO3–0.04BaTiO3 (BNKBT88) with copper. A combination of Bi2O3, CuO, ZnO, Li2CO3, and B2O3 are used as additives to reduce firing temperature to 900°C with minimal effect on the electromechanical properties compared to sintering at 1150°C without additives. Co‐firing with copper electrodes requires controlled oxygen sintering at low temperature. The atmosphere is controlled using carbon dioxide and hydrogen gas to maintain an oxygen partial pressure of 6.1 × 10−8 atm, which is necessary for the coexistence of Cu metal and Bi2O3. The thermodynamic activity of bismuth oxide in BNKBT88 is calculated to be 0.38. BNKBT88 ceramics were successfully co‐fired with internal as well as surface Cu metal electrodes. The copper co‐fired ceramics were successfully polarized and the dielectric and piezoelectric properties are evaluated.

New high temperature dielectrics: Bi-free tungsten bronze ceramics with stable permittivity over a very wide temperature range

“…Thermodynamic calculations indicate MLCCs would have to be co-fired at temperatures <940°C, and oxygen partial pressures, Po 2 < 10 -7 atm. [14]. By adding a series of liquid forming sintering fluxes to a Na 0.5 Bi 0.5 TiO 3based piezoceramic formulation, it proved possible to reduce the sintering temperature from 1150°C to 900°C, thereby enabling Cu electrodes to be demonstrated, but dielectric losses were higher than for samples fired in air [14].…”

“…[14]. By adding a series of liquid forming sintering fluxes to a Na 0.5 Bi 0.5 TiO 3based piezoceramic formulation, it proved possible to reduce the sintering temperature from 1150°C to 900°C, thereby enabling Cu electrodes to be demonstrated, but dielectric losses were higher than for samples fired in air [14]. A further issue or Bi-ceramic dielectrics relates to loss of volatile bismuth oxide during ceramic processing.…”

PersonalitySensing: A Multi-View Multi-Task Learning Approach for Personality Detection based on Smartphone Usage

“…Thermodynamic calculations indicate multilayers would have to be co-fired at temperatures <940°C, and oxygen partial pressures, Po 2 < 10 −7 atm. [14]. By adding a series of liquid forming sintering fluxes to a Na 0.5 Bi 0.5 TiO 3 -based piezoceramic formulation, it proved possible to reduce the sintering temperature from 1150°C to 900°C, thereby enabling Cu electrodes to be demonstrated, but dielectric losses were higher than for samples fired in air [14].…”

“…[14]. By adding a series of liquid forming sintering fluxes to a Na 0.5 Bi 0.5 TiO 3 -based piezoceramic formulation, it proved possible to reduce the sintering temperature from 1150°C to 900°C, thereby enabling Cu electrodes to be demonstrated, but dielectric losses were higher than for samples fired in air [14]. A further issue or Bi-ceramic dielectrics relates to loss of volatile bismuth oxide during ceramic processing.…”