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A novel sol-gel derived LiTa3O8 film sample was prepared on the Pt/Ti/SiO2/Si(100) substrate using the lithium ethoxide and tantalum ethoxide as starting materials. The 0.2mol/L sol of LiTa3O8 was prepared by reacting lithium ethoxide with tantalum ethoxide in 2-methoxyethanol and acetic acid in argon atmosphere to prevent humidity. The sol of LiTa3O8 was firstly diluted to 0.1mol/L and then covered on the Pt/Ti/SiO2/Si(100) substrate to form wet film with the condition of the spin-coating speed of 3000~7000 r.p.m. for 30~60 second. Pyrolysis of the prepared wet film was carried out in oxygen atmosphere at temperature of 420~450ºC for 2~5 min to remove the residual organics. Annealing of the prepared film was performed at temperature of 750~900ºC for 2~4 min in the rapid thermal process furnace to crystallize the prepared film layer. More layers of LiTa3O8 film can be added by repeating the spin-coating and pyrolysis steps prior to the final firing. It was found that up to 18 layers of LiTa3O8 film sample can be deposited before the films begin to exhibit signs of cracking. The performance parameters such as orientation, surface morphology, grain size and thickness of the prepared LiTa3O8 film sample were studied by XRD and SEM. The structure of the LiTa3O8 film is similar to orthorhombic, different from LiTaO3 film based on XRD pattern. The SEM micrograph reveals that the prepared LiTa3O8 film sample is uniform, smooth and crack-free on the surface with a thickness of 1 µm after crystallized at 750ºC. The pyroelectric property of the LiTa3O8 film sample was measured by the home-made water-bath heating pyroelectric coefficient measurement system. The measurement result shows that the novel LiTa3O8 film sample has pyroelectric property and its pyroelectric coefficient is 14.07μC/m2K after the sample is subjected to the DC poling of 6V, 15min. The experimental results verify the pyroelectric coefficient of the novel LiTa3O8 film is smaller than that of 122.80μC/m2K of the LiTaO3 film. The pyroelectric coefficient of the LiTa3O8 film will be improved with the development of the prepared process and adopting higher poling voltage.
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