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Well-defined polarization-electric field double hysteresis loops are rarely observed in pure NaNbO3 (NN) ceramics due to the metastability of the field-induced ferroelectric phase. In order to stabilize the antiferroelectric phase, various ABO3-type binary oxides were incorporated into a NaNbO3 ceramic, where the B-site is occupied with transition elements. In this work, CaSnO3 was chosen to construct the NaNbO3-based solid solution by reducing the Goldschmidt tolerance factor and ionic polarizability. X-ray diffraction patterns, transmission electron microscopy images, and Raman spectra indicate enhanced antiferroelectricity. Typical double hysteresis loops were also observed from polarization-electric field measurements in ambient conditions with slightly weakened maximum polarization as the content of CaSnO3 increased. Our results reveal the generality of this strategy and pave the way for various applications involving high-power energy for NaNbO3-based ceramics. [ABSTRACT FROM AUTHOR]

Practical pyroelectric materials require excellent pyroelectric performance, high depolarization temperature, and good temperature stability. In this work, the microstructure, ferroelectric, dielectric, and pyroelectric properties were studied systematically in (Bi0.5Na0.5)TiO3–0.1%MnCO3 (BNT–Mn) lead-free ceramics. It is observed that the pyroelectric coefficient p reaches 2.90 × 10−4 C m−2 K−1 at room temperature in the samples. Due to the low dielectric constant (291) and dielectric loss (0.010), the figures of merit (FoMs) Fi, Fv, and FD are as high as 1.03 × 10−10 m/V, 4.05 × 10−2 m2/C, and 1.86 × 10−5 Pa−1/2, measured at 1 kHz. With the increase in temperature, the p and FoMs change slightly, showing good temperature stability. More importantly, a relatively high depolarization temperature of 205 °C is achieved, which should help deliver reliable operation in practice. In general, all performances reveal that BNT–Mn ceramics are expected to pave the way for uncooled infrared detector applications. [ABSTRACT FROM AUTHOR]

The current decay characteristic in the time domain is studied in Y3+ and Mn2+ modified Ba0.67Sr0.33TiO3 ceramics under different temperatures (25 °C-213 °C) and voltage stresses (0 V-800 V). The decay of the current is correlated with the overlapping of the relaxation process and leakage current. With respect to the inherent remarkable dielectric nonlinearity, a simple method through curve fitting is derived to differentiate these two currents. Two mechanisms of the relaxation process are proposed: a distribution of the potential barriers mode around room temperature and an electron injection mode at the elevated temperature of 110 °C. [ABSTRACT FROM AUTHOR]

(Pb0.325Sr0.675)TiO3 (PST) ceramics were prepared by a traditional solid-state reaction technique. The dielectric and enhanced pyroelectric properties of PST ceramics were investigated under a DC bias field. The dielectric permittivity and dielectric loss of PST ceramics at Curie temperature were 2.97 × 10-4 and 0.006 without DC bias field, respectively. With a DC electric field of 0-500 V/mm, the maximum pyroelectric coefficient and the largest figure of merit (Fd) of PST ceramics were obtained, about 60 × 10-8 C cm-2 K-1 and 26 × 10-5 Pa-1/2, respectively. PST ceramics with such superior electric field enhanced pyroelectric properties have the potential for uncooled focal plane array detectors application. [ABSTRACT FROM AUTHOR]