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 Sr2Nb2O7 ceramics with different average grain sizes from 1.2μm to 3.6μm 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 d33 of(1:7
0:1)pC/N while still with a very high T_(c) of(1340±4)℃.The thermal depolarization temperature of samples with large grain sizes reach over 1200℃ 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.