Research On Template-free Solid-state Fabrication,Structure And Properties Of Alkali Metal Niobate And Titanate Micro-nanowires

Alkali metal niobates and titanates have good ferroelectric,piezoelectric,and photocatalytic properties.Because of their versatility,they are widely used in the field of scientific research.And nano-materials also have very good application prospects in the field of science and technology,such as the production of nano-sensors,light-emitting diodes,integrated circuits,biological probes,etc.,so they have also caused extensive research all over the world.Similarly,alkali metal niobate and titanate nanomaterials also have very large application prospects.Therefore,the research on alkali metal niobate and titanate nanomaterials is of great significance.At present,there are few studies on various aspects of alkali metal niobic acid and titanate micro-nanowires.In this paper,based on the first template-free solid-phase synthesis of alkali metal niobate micro-nanowires in our laboratory,the method is used to prepare alkali metal niobate micro-nanowires,focusing on the phase structure of alkali metal niobate micro-nanowires.The adjustment is an attempt to transform it from a tungsten bronze structure to a perovskite structure,so that it has ferroelectric properties,but the results of the adjustment are not ideal.In addition,in the process of developing alkali metal titanate micro-nanowires,some different but interesting phenomena have also been discovered,and special research has been carried out on this.The specific research results are summarized as follows:First,TiO₂-doped alkali metal niobate micro-nanowires with a tetragonal phase tungsten bronze structure were prepared by the traditional solid-phase method,and the growth,structure,composition,and composition of TiO₂-doped alkali metal niobate micro-nanowires were studied.performance.The results of the study show that the micro-nanowires are like plants growing out of the soil,directly growing vertically from the ceramic matrix,densely arranged together in a"small forest"shape,and the thickness of each micro-nanowire is basically uniform.A single micro-nanowire is composed of countless parallel and close-contacting elongated micro-nanowires arranged together.The tetragonal tungsten bronze structure of the micro-nanowires is different from the perovskite structure of the ceramic matrix.Moreover,from the comparison of the composition of the ceramic matrix powder and the non-doped TiO₂micro-nanowire powder,it can be seen that the atomic percentage of K and Na elements in the non-doped TiO₂micro-nanowire powder is significantly reduced.The TiO₂-doped alkali metal niobate micro-nanowire powder was used as a catalyst to degrade the methylene blue solution,and the photocatalytic performance of the micro-nanowire was studied.The results showed that during the degradation of the methylene blue solution by the micro-nanowire powder,the UV spectrum absorption peak intensity of the solution decreased successively,and with the increase of time,the degradation effect of the micro-nanowire powder on the methylene blue solution increased.Secondly,for the above-mentioned alkali metal niobate micro-nanowire with tetragonal phase tungsten bronze structure,the phase structure of the micro-nanowire is adjusted by hydrothermal method.The influence of the change of reaction medium,reaction time and solution concentration on the phase structure of micro-nanowires was studied.The results show that within the scope of the study,changes in the reaction medium,reaction time,and solution concentration did not change the phase structure of the micro-nanowire,and it was still a tetragonal tungsten bronze structure.However,in the hydrothermal solution,the micro-nanowires will continue to grow by swallowing the raw material molecules in the solution,resulting in a significant increase in the diameter of the micro-nanowires,the degree of crystallization of the micro-nanowires becomes higher,and the micro-nanowires The morphology of the line has also undergone a certain change.From the comparison of the atomic percentage of the micro-nanowire powder before and after the hydrothermal reaction,it can be seen that the atomic percentage of K and Na in the micro-nanowire powder increases after the hydrothermal reaction.Finally,a series of experimental samples of Bi_0.5(Na_0.5K_0.5)TiO₃（BNKT）doped with a small amount of Li Bi O₃（LB）were prepared by the traditional solid-phase method,and the effect of LB doping amount and growth temperature on BNKT-based micro The influence of nanowire growth and structure.Studies have shown that by introducing trace amounts of LB into BNKT,the growth of BNKT-based micro-nanowires can be achieved,but the difference is that the micro-nanowires grow laterally in the matrix;they grow in a one-dimensional stacking manner along their length and in the radial direction.It grows in a two-dimensional layered stacking manner.The prepared BNKT micro-nanowires have a single tetragonal perovskite structure,and individual elements in the micro-nanowires are seriously lost;when the reaction temperature and holding time remain unchanged,increase the amount of doped LB and BNKT-based The amount of BNKT micro-nanowires grown in the ceramic matrix has increased significantly;ensuring that the LB doping amount remains unchanged and the reaction temperature is increased,the size of the micro-nanowires increases slightly,and the number of micro-nanowires first increases and then decreases.The high temperature in the process caused serious warping and deformation of the ceramic substrate.The growth mechanism of BNKT-based micro/nanowires was briefly discussed.