Synthesis and performance characterization of pyroelectric lithium tantalate coatings
[Background]The operation of marine reactors and floating nuclear power plants is challenged by the thermal fluctuation of heat transfer surfaces caused by oceanic motion.The pyroelectric effect of lithium tantalate(LiTaO3,LT),a material with high Curie temperature and low relative dielectric constant that changes its spontaneous polarization with temperature variations,has the potential to influence the wettability of surfaces,thereby improving heat transfer performance.[Purpose]This study aims to prepare LT coatings with controlled pyroelectric properties and to investigate the mechanism of temperature-dependent wettability of LT,thereby enhancing heat transfer efficiency in two-phase systems.[Methods]First of all,the sol-gel method was used to achieve the controlled synthesis of LT.Subsequently,scanning electron microscopy(SEM)was employed to characterize micro surface morphology of coatings whilst the crystal phases and crystallinity in LT coatings were analyzed by X-ray diffraction(XRD)patterns.Then,the effects of synthesis parameters on the crystallinity,coating quality,particle size and pyroelectric properties of LT coatings were explored by systematically changing the curing time,sol settling time and annealing temperature in the sol-gel method.Finally,the pyroelectric effect and mechanism of wettability modulation were investigated by evaluating the hydroxyl radicals generated during temperature changes.[Results]The results indicate that the particle size of LT increases with increasing annealing temperature.The pyroelectric characteristics are significantly influenced by the thickness and particle size of the coatings,pyroelectric performance is enhanced by increasing the coating thickness and decreasing the particle size.Fluorescence spectroscopy analysis shows that the hydroxyl radical concentration of LT increases during the heating process,confirming that LT has the ability to regulate the hydroxyl radical concentration when undergoing heating and cooling cycles.[Conclusions]Results of this study demonstrate that LT coatings have temperature-dependent surface wettability of heat transfer in two-phase system with variable temperature.
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