ABO₃ Type Oxide Resistive Switching And Photocatalytic Properties Research

ABO3-type oxides BaTiO3(BTO)and BiFeO3(BFO)as the ferroelectric materials and semiconductor perovskite oxide materials,which have widely application in the fields of microelectronics,ferroelectricity and optoelectronics.Such as resistive random access memory(RRAM)and photocatalyst.On the one hand,with the fast development of information technology and computer science,the demands for good memorizer are becoming more urgent.However,the traditional RAM with low operation speed,bad endurance and high power consumption,What’s more,they also treated as the considered a promising candidate for the next generation of resistive random access memory(RRAM).At present,resistance transition characteristics are studied by adjusting defects,which has been a research hotspot in resistive random access memory area.On the other hand,recent years have witnessed that ABO3 oxides,as a promising candidate for photocatalysis,were employed to degrade persistent organic pollutants such as Rhodamine,methylene blue and methylene orange.However,suffered from the wide band gap,most ABO3-type oxides exhibits poor photo-absorption capability in visible light and high rate of recombination of photoexcited carriers,it had been tried to decorate with metal nanoparticles to enhance the photo-absorption of visible light.This paper focuses on the study of barium titanate and bismuth ferrite.Through simple preparation process,the resistance transition characteristics and photocatalysis property of BTO and BFO are studied in this paper.The main research contents are as follows:(1),The resistance transition characteristics of BFO thin films were studied by different annealing temperatures.We can see that the resistance window gradually be opened with the increasing annealing temperature.Finally,the ON/OFF ratio was 104 when the BFO thin film annealed at 650℃.The X-ray photoelectron spectroscopy(XPS)with KV indicates that cation ratio of Fe2+/Fe3+ is increased with increasing annealing temperature,which improve the ON/OFF ratio.Crystal lattice distortion generated by Fe2+ cations,along with oxygen vacancies commonly contribute to opening the RS window and the increment of conductive filaments.The increased oxygen vacancies lead to the number of conductive filaments.The leakage current was enhanced due to the effect of Fe2+ and oxygen vacancies,which results in improved resistance switching characteristics of BiFeO3 thin film.Moreover,the conduction mechanism of BFO are studied by linear fitting.(2),Modulation of resistive switching characteristics for individual BaTiO3 microfiber by surface oxygen vacancies in different annealing atmosphere.Individual sol-gel BTO microfiber has been formed using the draw-bench method,followed by annealing in different atmospheres of air and argon,respectively.After testing the X-ray photoelectron spectroscopy(XPS)and Raman spectroscopy(Raman),we found that the sample annealed in argon ambience show more oxygen vacancies in the surface of BTO fibers than the sample annealed in air.After I-V test,it indicated that the sample annealed in air,the average resistive ON/OFF ratio is as high as 108,enhanced about four orders in comparison with the counterpart that annealed in Argon.On the one hand,the different oxygen vacancies results in the electron concentration on high resistive state,on the other hand,for the sample annealed at argon exhibits thinner barrier,which contributes the lower threshold voltage.Finally,we studied the conduction mechanism in high resistance state and low resistance state for both BTO sample by linear fitting.(3),Gold nanoparticles Decorated on BaTiO3 and studied the photocatalysis property.BaTiO3(BTO)powders with cubic(C)and tetragonal(T)crystalline structures were prepared by sol-gel method followed by calcination at different temperatures,and they were decorated with gold nanoparticles(Au NPs)to form Au-T-BTO and Au-C-BTO by oil circumfluence respectively.All the samples(C-BTO,T-BTO,Au-C-BTO and Au-T-BTO)were used as photo-catalysts for the degradation of Rhodamine B(RhB).Au-T-BTO exhibits the highest photocatalytic activity due to the combined effect of surface plasmon resonance(SPR)and the ferroelectricity of the tetragonal phase BTO.The light absorption peaks at 500 to 600 nm verify the presence of SPR effect from Au NPs.Based on density functional theory(DFC)within the generalized gradient approximation(GGA)approach,it was demonstrated that the tetragonal phase BaTiO3 shows a spontaneous polarization with the calculated value of 0.34 C/m2,which is absent in the cubic phase.The internal space charge layer in tetragonal phase BTO enhances the separation of photoexcited carriers due to the spontaneous ferroelectric polarization,which also benefits photocatalytic activities.