Grain size effect on piezoelectric properties of Sr 2 Nb 2 O 7 ceramics

Grain size effect on piezoelectric properties and thermal stability of perovskite layer structured (PLS) Sr 2 Nb 2 O 7 ceramics are investigated. The Sr 2 Nb 2 O 7 ceramics with different average grain sizes from 1.2[Formula: see text][Formula: see text]m to 3.6[Formula: see text][Formula: see text]m were prepared in different sintering temperatures by solid state reaction method. The average grain size increases, accompanied by a higher relative density of up to 96%. Pure Sr 2 Nb 2 O 7 ceramics with larger grain size show a remarkable [Formula: see text] of ([Formula: see text])pC/N while still with a very high [Formula: see text] of ([Formula: see text]C. The thermal depolarization temperature of samples with large grain sizes reach over 1200 ∘ C and the thermal stability increased with increasing of grain size. The ferroelectric domains structure was observed by PFM and larger grain is easy to form ferroelectric domain then enhance piezoelectric properties. This study demonstrates enhanced piezoelectric properties can be achieved in pure Sr 2 Nb 2 O 7 by solid state reaction method and bring great revitalization to the Sr 2 Nb 2 O 7 -based ceramics as a promising high-temperature piezoelectric material.