Hot-press sintering Sr2Nb2O7 ceramics and their electrical properties

Sr2Nb2O7 ceramics with high densities were synthesized by the hot-press sintering process, and the effects of sintering temperature and holding time of phase composition and microstructure were studied. The dielectric, piezoelectric, and ferroelectric properties of Sr2Nb2O7 ceramics were also investigated. A relative density of 98% was obtained when the Sr2Nb2O7 ceramics were prepared by hot-pressing (30 MPa) at temperature as low as 1200 °C for 2 h. The grain size of Sr2Nb2O7 increases gradually with the variation of temperature from 1150 to 1200 °C. The grains are plate-like and the length of grain size is 15 µm when the temperature increased to 1200 °C. In addition, the grain boundary became unclear at 1300 °C for 2 h. The dielectric constant and dielectric loss of the ceramics sintered at 1200 °C for 2 h were 57 and 1.6% at 10 kHz, respectively. The piezoelectric constant reached 2.1 pC/N. The remanent polarization and the coercive field were 0.24 µC/cm2 and 15.1 kV/cm, respectively.