Construction Of Solid Electrolyte Emitters And Study Of Their Ion Extraction Properties

Solid electrolytes with a high ionic conductivity at ambient temperature could potentially be used for solid-state batteries,memory devices,display panels,electrochemical capacitors,etc.Using solid-state batteries in microelectronics is an attractive application because of their advantages of reliability and choice of device geometries which result from the absence of leaking liquids.Fast ionic conductors,also known as superionic conductors and sometimes solid electrolytes,are characterized by extremely high ionic conductivity(10¹>σ_i>10^-5 S/cm,negligible of electronic conductivity)and low ionic conductivity activation energy（≤0.40 e V）.Most fast ion conductors are inorganic compounds,and many organic materials are fast ion conductors of silver,copper and hydrogen ions.Most of the fast ion conductors used for basic research are single crystals,but polycrystalline materials are often used in practical applications.Recently,research on amorphous fast ion conductors has begun.In terms of designing new ionic solid materials and exploring their application potential,especially driven by the demand for new clean energy,ion beam modification,sensors and high energy density batteries,the pace of research has gradually accelerated,gradually forming a research focus in contemporary materials science.Nowadays,the field-assisted thermionic emitter technology based on solid electrolytes（anion conductors）is relatively mature,such as 12Ca O·7Al₂O₃,Y:Zr O₂which can generate negatively charged oxygen ion beams.The main disadvantage of this type of ion emission device is that the working temperature is too high（500-700°C）,and the emitted ions are mostly light ions.These shortcomings limit the application of field-assisted thermionic emitters as ion propulsion devices in small spacecraft such as Cube Sats.Solid electrolytes containing Ag I and Cu I have high ionic conductivity and good stability at room temperature,so they have become widely studied typical ionic conductors.Copper-based ionic conductors are very similar in properties to silver-based ionic conductors,with abundant resources,low manufacturing costs,simple synthesis processes,and different application fields（such as copper interconnects）from silver-based ionic conductors.Therefore,this work takes copper-based electrolytes as the research point and develops a low-energy copper ion beam generator-copper-based solid electrolyte ion source（SEIS）.The preparation process,structure and composition analysis,ion source design and trial production of solid electrolyte materials are systematically studied,beam emission characteristics.The main research work is divided into the following three aspects:（1）Preparation of solid electrolyte materials and research on their structure and properties.The copper ion solid electrolyte Rb₄Cu₁₆I₇Cl₁₃ was prepared by mechanochemical ball milling,and the synthesis process was systematically explored with three components of high purity Cu Cl,Cu I and Rb Cl as raw materials,and the optimal ball milling process for synthesizing copper-based solid electrolyte was determined.parameters,that is,at 480 rpm and 6 hours,a pure solid electrolyte phase was successfully obtained.The crystal structure of the obtained Rb₄Cu₁₆I₇Cl₁₃ was analyzed by powder refining Rietveld,and the crystal structure,surface morphology,physical and chemical properties and melting point were analyzed;Secondly,the ionic conductivity of Rb₄Cu₁₆I₇Cl₁₃ was analyzed by AC impedance spectroscopy,and the corresponding conductivity and activation energy values were obtained by fitting the equivalent circuit,which was in line with the Arrhenius equation,and the influencing factors of the copper ion conductivity were analyzed;Finally,the composition stability and conductivity stability of the solid electrolyte were analyzed after being stored in the natural environment for 12 days.（2）Design and debugging of solid electrolyte ion source measurement device.To measure the ion emission characteristics of the solid electrolyte,a field emission ion source experimental device is designed and established,which was composed of a field emission ion source,an ion optical path,ion beam current testing system,a high voltage power supply system and a vacuum system.The ion source is composed of an emitter,a heater,and an extraction electrode.The temperature control range of the heater is 30-300°C,and the working pressure of the vacuum chamber is better than 10^-4Pa.The extracted ion beam enters the ion beam path composed of high voltage acceleration,electrostatic focusing and Wien displacer.The solid electrolyte ion source generates the ion beam in the form of a tip emitter,and the tip curvature radius is r<10μm.The ion emitter is composed of a high-purity metal ion-based source and a solid-state transmission channel.The working voltage of the electrostatic acceleration system is continuously adjustable from 0 to 20 k V,and the electrostatic focusing uses a three-cylinder lens to simulate the calculation and optimize the influence of parameters such as working voltage on the ion beam diameter.By adjusting the size of the pre-focusing voltage,the ion beam focusing system is installed and debugged,and the SEIS emitter is used to carry out to test,observe the ion beam focusing characteristics,and receiveμm-level ion beam current.（3）Study on the ion emission characteristics of solid electrolyte emitters.A sharp needle tip was made from a high-purity copper rod by mechanical sharpening and manual grinding,and then the copper-based solid electrolyte Rb₄Cu₁₆I₇Cl₁₃ was deposited on the surface of the needle tip to make an SE/Cu emitter.The preparation process and working conditions were optimized,and the ion beam emission characteristics of the emitter under vacuum conditions were measured,such as the variation characteristic curves including of ion beam intensity with working temperature（I-T）and voltage（I-U）,and a stable copper ion beam was obtained.The study of the physical laws and physical models related to the I-U curve provides corresponding technical and theoretical help for field ion emission.Finally,the factors affecting the ion beam size are discussed.（4）Ion implantation study.A copper ion beam with high purity was implanted into the single crystal silicon surface and copper nanoparticles were formed.The elemental composition of the ion beam was detected,which was verified the main component of the ion source was copper ions.The morphology and size distribution,depth distribution of Cu NPs were studied and the formation process of Cu NPs were further analyzed.Finally,the photoluminescence properties of Cu NPs under near-ultraviolet light excitation was discussed.The solid electrolyte ion source developed in this work has the characteristics of simple structure and low operating temperature,which plays the foundation for the development of a field emission ion beam device for nanofabrication（copper interconnection）and ion propulsion.