Piezoelectricity

Physics

Dopant

Grain size

Sintering

Analytical Chemistry (journal)

Ceramic

Composite material

Mineralogy

Nuclear physics

Chemistry

Reducing atmosphere

Metallurgy

Materials science

Grain boundary

Grain growth

Chromatography

Optoelectronics

Volatilisation

Doping

Microstructure

Journal of Advanced Ceramics

It is a very difficult work to sinter K 0.5 Na 0.5 NbO 3 (KNN)-based materials with good reduction resistance in strong reducing atmosphere. 0.945K 0.48 Na 0.52 Nb 0.96 Ta 0.04 O 3 −0.055BaZrO 3 + 0.03ZrO 2 + y mol%MnO (KNNT−0.055BZ + 0.03Zr + y Mn) ceramics sintered in reducing atmosphere were prepared successfully by conventional solid-state reaction methods. MnO dopant increases grain size at y = 5–8 due to strong lattice distortion and then decreases grain size at y = 9 due to much Mn 4 Nb 2 O 9 accumulated at the grain boundary. MnO dopant as an excellent sintering aid can effectively reduce volatilization of alkali metal by decreasing the sintering temperature ( T sinter ). Reducing alkali metal volatilization can greatly reduce oxygen vacancies and improve piezoelectric properties. MnO dopant can improve the anti-reduction properties. The KNNT−0.055BZ + 0.03Zr + y Mn ceramics at y = 6–9 show outstanding anti-fatigue of unipolar piezoelectric strain under the synergistic effect of reduced oxygen vacancies due to reduced volatilization and increased grain size. Piezoelectric properties and temperature stability of KNNT−0.055BZ + 0.03Zr ceramics sintered in reducing atmosphere are improved simultaneously by MnO dopant. Optimum inverse piezoelectric coefficient ( d 33 * ) of ceramics at y = 8 reaches up to 480 pm/V under low driving electric field E = 20 kV/cm at room temperature, and its temperature stability of d 33 * reaches 158 °C. It will be an excellent lead-free material candidate for the preparation of multilayer piezoelectric actuators co-fired with nickel electrode.

Simultaneously improving piezoelectric properties and temperature stability of Na0.5K0.5NbO3 (KNN)-based ceramics sintered in reducing atmosphere