Fabrication Of Optical Waveguide And Analysis Of Solid-electrolyte Interphase With Ion Beam Technique

Ion beam technique has become an excellent method for surface modification and surface analysis after several decades of development.The interaction between ions and target materials can result in deposition,sputtering,doping and so on,which therefore makes ion beam technology has important application value in different fields.In this dissertation,ion beam technology is mainly used to study in two aspects:(1)Optical waveguide structures are fabricated with ion irradiation technology,and the characteristics of the waveguide structures are studied;(2)The use of time-of-flight secondary ion mass spectrometry for solid-liquid interface(SEI)was studied.The solid-electrolyte interface layer of lithium ion battery is studied and the diffusion rate of lithium ions in SEI layer is calculated.In this paper,different optical materials were irradiated with ions,and the optical waveguide structure was prepared by changing the microstructure characteristics of optical materials.The structural changes of the waveguide structure before and after ion irradiation were characterized.The main content is the change of lattice structure caused and defects.At the same time,its optical properties were studied,mainly including the distribution of refractive index and near-field intensity distribution.Experimental and theoretical methods were used during the waveguide research.Experimental methods include:prism coupling method detected the effective refractive indices of guided modes;end-face coupling method detect the near-field intensity distribution profiles;Raman spectra characteristic the structure change after ion irradiation.Theoretical methods include:reflectivity calculation method(RCM)calculated refractive index profile based on the effective indices of guided modes;beam propagation method calculated near-field intensity distribution profiles based on the refractive index distribution;the Stopping and Range of Ions in Matter(SRIM)software simulated the ion irradiation process.Optical waveguides were fabricated on chalcohalide glass,Nd:Li6Y(BO3)3 crystal,and LiNbO3 crystal in this dissertation.The chalcogenide glass mainly refers to a glass material formed of three elements of S,Se,and Te,and introducing a small amount of other metal elements.A planar waveguide structure was fabricated in chalcohalide glass using dual-energy C ion implantation with 5.5 and 6.0 MeV C ions at fluences of 7 × 1014 and 8 × 1014 ions/cm2,respectively.We explored the structural properties of chalcogenide glass after irradiation.The optical transmission characteristics of the optical waveguide structure in the visible and near-infrared bands were studied.The results show that the waveguide structure fabricated in chalcohalide glass by dual-energy C ions implantation has a wide optical barrier,which can iedeally confine the light propagation.Single crystal of the double alkali-rare-earth borate Li6Y(BO3)3(LYB)belongs to monoclinic system and P21/c space group with a = 0.7157 nm,b = 1.6378 nm,c =0.6623 nm.A planar waveguide structure was fabricated using C ion irradiation with energy of 6 MeV at a fluence of 2.5 × 1015 ions/cm2.The light transmission property was studied in the visible and near-infrared band.The results show that the waveguide structure fabricated in LYB material can support multi-mode in visible region and single mode in near-infrared region.Lithium niobate(LiNbO3)lithium niobate crystals belong to the trigonal system,waves of wavelengths between 350 nm and 5200 nm can be transmitted.LiNbO3 crystal was irradiated with Ar ion with energy of 70 MeV and fluences of 1×1012 ions/cm2 to fabricate the waveguide structure.The optical and structural properties of the waveguide structure were studied.The results prove that Ar ion irradiation of lithium niobate crystal waveguide structure can well support the transmission of visible light and near-infrared wave band.If the ion energy is between 100 eV and 100 keV,the ion beam will create a sputtering effect on the surface of the material.Particles that escape due to ion beam sputtering include atoms,molecules,molecular clusters,and extremely small amounts of charged ions.These charged ions are called secondary ions.If the sputtered secondary ions are accelerated by the electric field and passed through a detector having a mass analysis function,the information of the chemical composition on the surface of the target material can be obtained,that is,Secondary Ion Mass Spectrometry(SIMS).Due to the extremely high sensitivity of SIMS,sample detection needs to be performed under high vacuum(less than 10-5 mbar)to prevent gas molecules in the environment from adsorbing on the sample surface causing sample contamination or disturbing secondary ion sputtering to the sensor.Therefore,the samples detected by secondary ion mass spectrometry are generally solid.In order to achieve the detection of liquid sample detection,the concept of in situ liquid SIMS was proposed in 2011.One of its most unique features is the applicability of liquid surface,liquid-solid interface and liquid vacuum interface analysis.However,in the in situ liquid SIMS experiment,the primary ion beam causes damage accumulation on the liquid surface,and the resulting damage effects lead to instability of the experimental results.Therefore,It is important to optimize the experimental results of the liquid test by investigating different experimental conditions.In this paper,we studied the solid-state and solution systems of DPPC(Dipalmitoylphosphatidylcholine)samples,and compared the ion yield of traditional solid sample SIMS with that of liquid samples.When cluster ions(Bi3+ or Bi3++)were used as the analysis ion beam,the yield of both positive and negative ions(including molecular ion peaks and characteristic fragment ion peaks)reached a sufficiently high level,and in the liquid sample test,the damage caused by the ion beam can be alleviated.One of the reasons is that the sputter interface fluid is dynamic and fluid.The spoiled debris can be diffused into the substrate liquid from the sputter interface in time.At the same time,the complete DPPC molecules can diffuse from the substrate liquid to the sputter surface in time.Another reason is that sputter damage can be removed in time by the high sputter rate of the Bi3+ or Bi3++ ion primary ion beams.In addition to this,due to the unique nature of the liquid environment,the samples of the liquid SIMS are less fragmented.Therefore,even if the ion beam dose is high(1014-1016 ions/cm2)in the liquid SIMS test,ion beam damage can still be maintained at a sufficiently low range.During the first charge and discharge process of a lithium ion battery,a layer of solid-electrolyte-interphase(SEI)is formed at the interface of the electrode electrolyte.The presence of SEI layer has a crucial role for the performance of lithium-ion batteries.In-depth study of the chemical composition and structure,formation mechanism,and stability of the SEI layer has always been a research hotspot in the world chemical industry.We used the in-situ liquid SIMS technology to study the LiFSI-DME system.Before any interfacial chemical reactions occurred at the initial charge,a double layer was formed at the electrode-electrolyte interface.The formation of the electric double layer affects the interfacial chemical environment in the electrolyte,which causes the anion of the salt to stay away from the surface of the positive electrode,forming an inner SEI layer containing no LiF component.After the dense inorganic inner SEI layer is formed,a loose organic outer SEI layer is formed.The outer SEI layer has electrolyte permeability.The main function of the SEI layer is achieved by a dense inorganic inner layer whose main component is Li2O.Li2O is a substance having Li+ permeability and no electron permeability.In addition,the inner SEI membrane is very dense,and the solvated molecules and salt anions cannot diffuse into it,so it can effectively separate the lithium metal from the electrolyte.Electrode material is an important factor restricting the practical application of lithium ion batteries,and the diffusion ability of lithium ions can directly affect its electrochemical reaction power.Lithium ion diffusion is determined by internal factors and external factors.External factors include particle size,distribution,and morphology.Internal factors mainly refer to lithium ion diffusion coefficients.The study of the lithium ion diffusion coefficient is conducive to the improvement of the existing electrode materials and the design and development of new materials.The lithium battery model of LiClO4-EC/DMC system was studied by isotope labeling and the diffusion rate of lithium ions in the SEI film was calculated.In this dissertation,the optical waveguide structure was successfully fabricated by using ion beam technology in chalcogenide glass,Nd:LYB,and lithium niobate crystals.The prepared optical waveguide structures can support the transmission of light in the visible and near-infrared bands.At the same time,it was found that the dual-energy ion irradiation can widen the barrier width of the waveguide structure,thereby better limiting the transmission of the guided mode.The in-situ liquid secondary ion mass spectrometry method was used to test the liquid in a vacuum state.The effect of different primary ion beam and experimental conditions on the damage accumulation was investigated.The solid-electrolyte interphase of the lithium ion battery was studied at the same time.The main components of the SEI layer and the evolution process,the diffusion rate of lithium ions in the SEI film was studied.The experimental conditions of in-situ liquid secondary ion mass spectrometry were optimized to provide the experimental basis for the research of SEI layer.At the same time,the study of lithium ion diffusion rate provided the research basis for further improving the performance of lithium ion battery.