Studies of structural, electrical, and dielectric properties of a new ferroelectric: SrTi2O5

In this paper, structural, microstructure, electrical (impedance, conductivity), and dielectric properties (dielectric constant, tangent loss, and polarization) of a new ferroelectric ceramic (SrTi2O5) synthesized by a high-temperature solid-state reaction method have been reported. The crystallization of the compound in orthorhombic symmetry is confirmed by analyzing the room-temperature X-ray diffraction profile. The scanning electron micrograph displays nearly square and/or spherical grains with varying dimension. The energy-dispersive spectrograph displays desired stoichiometry of the prepared sample. The room-temperature hysteresis loop provides a saturation polarization of about 7.95 mu C/cm(2) suggesting the existence of ferroelectricity in the compound. In the temperature regime of 25-500 degrees C, at different frequency (1 kHz-1 MHz), the electrical and dielectric properties have been investigated. The average normalized change of impedance in the above temperature range signifies the footprint of different conduction processes above 250 degrees C. The Nyquist plots show non-Debye-type semicircular arc for each selected temperature. The grains and grain boundaries' contributions are found on fitting these arcs to the (R-g Q(g)) (R-gb Q(gb)) circuit. The conductivity study reveals the existence of distinct conduction processes in the grains and grain boundary regions. The dielectric constant increases with temperature rise at selected frequencies. The dielectric loss first increases with temperature, and about 270 degrees C, it follows relaxation phenomena in the low-frequency regime. In the high-frequency regime, its value increases with temperature rise. A low value of dielectric loss in the high-frequency regime nominates its possible application in microwave devices.