| Photostriction is the light-induced-non-thermal deformation in a material,Including stretching,bending,twisting and other deformation.Photostrictive materials have important application prospects in wireless optical drive drivers,micro-sensors and relays,light-controlled gas reservoirs and other potential optical mechanical applications.From the perspective of practical application,there are still many problems in the study of photoinduced deformation,such as slow response,small deformation and narrow light absorption range.The solution to these problems will accelerate the miniaturization of devices and promote the development of science and technology.Titanium dioxide(TiO2)is a typical photocatalytic semiconductor material,and has the advantages of cheap and easy to get,non-toxic,and will not cause secondary pollution.We speculate that it may have a potential photoinduced deformation effect.However,the absorption range of titanium dioxide is relatively narrow,and it is partial to the ultraviolet part,so the light energy utilization rate is not high.The purpose of this study is to examine the possible photoinduced deformation effect of titanium dioxide and expand its spectral response range,so as to lay a foundation for practical application.The research contents and innovative achievements are as follows:The photostrictive properties of rutile TiO2 ceramics were studied for the first time.In the first place,anatase TiO2 powder was sintered into rutile TiO2 ceramic under 1050? by using the method of discharge plasma sintering(SPS)for us.The results of uv-vis absorption spectrum characterization shows that the band gap of the synthesized rutile TiO2 was narrower than that of anatase TiO2 and had a weak absorption of visible light.Photostriction of titanium dioxide ceramics was tested,Photostriction of titanium dioxide ceramics were respectively 1.6×10-3,1.8×10-3 and 7×10-4 under the laser irradiation in wavelength of 405 nm and light intensity of 22.3 kWm-2,wavelength of 520 nm and light intensity was 67.6 kWm-2,wavelength of 655 nm and light intensity of 41.2 kWm-2.The average response speed of photostriction is about 6 seconds,and the response speed is much faster than that of organic polymer,and was equal to that of ferroelectric materials.In order to regulate band gap of TiO2,broaden its range of light absorption,enhance the absorption of visible light,TiO2 ceramics were annealed at 600?,650?,700?,750?,800 ?,850? under ammonia gas atmosphere on the nitrogen doping.Results of XRD and uv-vis absorption spectra show that there is no phase transition in the doping process of TiO2 ceramics,and the N atom was doped into the TiO2 lattice.Photostriction of N-doped titanium dioxide ceramics was tested,the largest photostriction of N-doped TiO2 ceramics under 600? was 1.6×10-3 under the laser irradiation in wavelength of 405nn nm and light intensity of 22.3 kWm-2;the largest photostriction of N-doped TiO2 ceramics under 750? was 2.4×10-3 under the laser irradiation in wavelength of 520 nm and light intensity of 67.6 kWm-2;the largest photostriction of N-doped Ti02 ceramics under 800? was 1.9×10-3 under the laser irradiation in wavelength of 655 nm and light intensity of 41.2 kWm-2,and it is about three times of photostriction of pure rutile TiO2 ceramicsIn situ XRD analysis showed that the pure phase TiO2 ceramics and N-doped TiO2 ceramics did not undergo phase transformation during the laser irradiation,but the deformation was resulted by the lattice changes induced by light.Therefore,we believe that the photostriction of non-polar semiconductor ceramics is related to the change of atomic bond length caused by excessive light-excited carriers in the conduction band. |
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