Pin Liu

Large enhancement of the electrocaloric effect in PLZT ceramics prepared by hot-pressing

In this contribution, we demonstrate the optimization of the microstructures of the Pb0.85La0.1(Zr0.65Ti0.35)O3 (PLZT) relaxor ferroelectric ceramics and subsequent enhancements in their polarization and electrical resistivity by using a hot-pressing process. The resulting superior breakdown strength of hot-pressed PLZT enables the application of high electric field to induce a giant electrocaloric effect, in which the adiabatic change of temperature (ΔT) and the isothermal change of entropy (ΔS) are around 2 times greater than those of the samples prepared by the conventional sintering approach using muffle furnace. Moreover, the addition of extra PbO to make up the loss of Pb in the high-temperature sintering leads to the further improvements in the phase composition and electrical properties of PLZT, due to inhibition of the pyrochlore phase formation. The relationship among the sintering conditions, the content of excess PbO, and the microstructure as well as the electrical characteristics of PLZT hav...

Molybdenum and tungsten doped SnO2 transparent conductive thin films with broadband high transmittance between the visible and near-infrared regions

We demonstrate an approach for the synthesis of SnO2 transparent conductive films with low square resistance and high transmittance over the visible and NIR regions via doping of molybdenum and tungsten. Crystallite grain agglomerations are evenly observed for each dopant, resulting in an obvious surface morphological evolution with increased doping concentration and annealing temperature. With Mo and W doping, the conductivity of doped SnO2 samples can be efficiently enhanced by one order. Meanwhile, the electrical property of the doped SnO2 samples sensitively responds to the doping concentration and annealing temperature due to the variation of carrier density, which even results in a square resistance of 0.26 kΩ □−1 of the SnO2:Mo:W sample. The doped samples steadily exhibit a relatively high transmittance of ∼60% over a wide wavelength range between 300 and 2500 nm, and the average transmittance of each sample is ∼2 times higher than that of ITO in the NIR region. Besides, the transmittance correspondingly increases along with the surface morphology evolution as a function of the doping concentration and annealing temperature due to light scattering.

Large energy density in Ba doped Pb0.97La0.02(Zr0.65Sn0.3Ti0.05)O3 antiferroelectric ceramics with improved temperature stability

Pb0.97La0.02(Zr0.65Sn0.3Ti0.05)O3 (PLZST) antiferroelectric ceramics containing various contents of Ba were fabricated via the conventional solid-state reaction approach, in which the dependence of the microstructure, ferroelectric feature, and energy storage performance and its temperature stability were studied in detail. The findings demonstrate that introducing an appropriate content of Ba is able to not only upgrade the electric polarization as well as the recoverable energy density, but also improve the temperature stability of the energy density in PLZST ceramics. Compared to the PLZST without Ba which has a recoverable density around 1.0 J cm−3, the PLZST added with 6 mol. % Ba possesses a favorable recoverable density of 2.4 J cm−3. Furthermore, the introduction of an adequate content of Ba results in a desirable temperature stability of 90% over a 100 °C temperature span. We envisage that the systemically investigation of the recoverable energy density and its temperature stability of the antiferroelectric ceramics in this work will benefit the exploration of a high performance of energy-storage technology for the electric power systems.

Characteristics of the PMnN-PMS-PZT pyroelectric ceramics for energy harvesting devices

abstract Pb[(Mn0.33Nb0.67)1/2(Mn0.33Sb0.67)1/2]0.08(ZrxTi1-x)0.92O3 (PMnN-PMS-PZT) pyroelectric ceramics with varied compositions were successfully prepared by the conventional solid state method. The microstructures and electric properties of three different Zr/Ti compositions, i.e. 94/6, 95/5 and 96/4 (in molar ratio) of the ceramics were studied. When x = 0.94, 0.95 and 0.96 in the ceramics, the maximum pyroelectric coefficient peaks appear at 43°C, 28°C and 34°C, and the maximum values are 21.0×10−4C/m2°C, 26.5×10−4C/m2°C and 16.0×10−4C/m2°C, respectively. And the ceramics of the three different Zr/Ti compositions were used to fabricate pyroelectric energy harvesting devices, which were evaluated by using an oven as the heating method. The maximum densities of surface charge achieved for the ceramics of the three compositions are 6.47×10−6C/cm2, 7.19×10−6C/cm2 and 4.31×10−6C/cm2, respectively. The obtained results indicate that the PMnN-PMS-PZT ceramic with Zr/Ti of 95/5 in molar ratio exhibits the best pyroelectric and ferroelectric properties, which may have potential applications in fabricating pyroelectric energy harvesting devices.