| As the rapid development in energy harvesting in recent years, energy harvesting using waste heat has been also paid more and more attention. Besides the thermoelectric energy harvesting based on temperature gradient, pyroelectric energy harvesting based on the change rate of temperature also begins to enter people's light sight. Pyroelectric materials are often used in applications of infrared detectors, the research on energy harvesting of pyroelectric effect using waste heat was studied less widely and deeply. Due to the merits of pyroelectric harvesting devices, such as small size, low power consumption, independent power supply, safe and reliable, it is an important subject in the international energy harvesting field. In order to improve the pyroelectric energy harvesting efficiency, further study in pyroelectric materials, device structures, heating methods and the optimal working frequenc ies are needed. This paper takes the Pb[(Mn0.33Nb0.67)1/2(Mn0.33Sb0.67)1/2]0.08(Zrx Ti1-x)0.92O3(PMn N-PMS-PZT) ceramic materials to fabricate the energy harvesting units, meanwhile the electrical characteristics of pyroelectric energy collector were also further studied.In this work, the capability of harvesting energy using Pb[(Mn0.33Nb0.67)1/2(Mn0.33Sb0.67)1/2]0.08(Zrx Ti1-x)0.92O3(PMn N-PMS-PZT) ceramics was studied. For this purpose, three different Zr/Ti compositions, i.e. 94/6, 95/5 and 96/4(in molar ratio) of the ceramics were prepared and characterized. The pyroelectric coefficient peak of Zr95 sample appears at 28 ?, with peak value 26.5×10-4 C/m2?, which is followed by a high averaged pyroelectric coefficient in a wide temperature range of 25 ?to 60 ?. All the three PMn N-PMS-PZT ceramic specimens show saturated P-E hysteresis loop, in which the Zr95 specimen shows the largest Ps and Pr, suggesting Zr95 has a better ferroelectric performance.Three different device configurations, including a monolithic ceramic, ceramic arrays and multilayered ceramics were studied, and the innovated multilayered ceramic structure proposed in this study showed advantages in energy conversion and collection efficiency, which were evaluated by using an oven and a Peltier cell as heating and cooling methods. The maximum densities of surface charge achieved for the three types of ceramic structures are 7.19×10-6 C/cm2,6.59×10-6 C/cm2,14.25×10-6 C/cm2, respectively, which are in general higher than that of the commercial lead zirconate titanate(PZT-5H).We also investigated the effects of temperature change frequency on the electrical response by using the monolithic ceramic device as an example. At a saturatio n frequency of 70 m Hz, the pyroelectric device shows an maximum output voltage of 1.961 V, an induced energy as high as 1.592 ?J and a power density of 3.138 ?W/cm3. The obtained results indicate that our proposed PMn N-PMS-PZT devices in general has a better pyroelectric performance than the commercial lead zirconate titanate(PZT-5H) pyroelectric devices.In general, the PMn N-PMS-PZT is one of the materials suitable for fabricating the pyroelectric energy harvesting devices. The multilayered structure shows much larger charge density than the parallel ceramic array structure, which may be attributed to the much larger effective device area. Further more, it shows great advantage in reducing the device dimension and increasing the effective area and absorption and release of heat. The above advantages are beneficial for the device miniaturization and integration, which may have potential applications in ultra- low-power devices and in wireless network systems. |
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