Improved resistivity in bismuth deficient morphotropic phase boundary 0.88BNT-0.08BKT-0.04BT ceramics

Acceptor doping is used to achieve hard piezoelectric properties by inducing oxygen vacancies. In Bi
_0.5
Na
_0.5
TiO
₃
(BNT) based ceramics, modifying the A-site stoichiometry can be used to achieve similar effect as acceptor doping, such as bismuth deficiency that induces oxygen vacancies. In this work 0.88Bi
_0.50-x
Na
_0.50
TiO
₃
- 0.08Bi
_0.50-x
K
_0.50
TiO
₃
- 0.04BaTiO
₃
(BNKBT88-xBi) ceramics with bismuth deficiency x≥0.02 have been prepared. The Bi-deficient ceramics have low dielectric loss, high mechanical quality factor of 1200, and coercive field of 48kV/cm. However, at elevated temperature the mobility of oxygen vacancies decreases resistivity, limiting the use of these ceramics for high power transducer application. The addition of bismuth oxide to the calcined Bi-deficient compositions improves piezoelectric, dielectric, ferroelectric, and electrical properties at elevated temperature. Mechanical quality factor over 900 was achieved for small Bi
₂
O
₃
addition.