A New Technique And Its Mechanism For Regulation Of Oxide Vacancy Assisted By The Out Field

Oxygen vacancy is one of the most important defects in oxide materials.Manipulation of distribution and concentration of oxygen vacancy is highly desirable for improving the performance of materials and devices including superconductivity,catalysis,ionic conductivity,fluorescence and electrochemical batteries,and so on.Some synthetic strategies have been developed to create intrinsic oxygen vacancies,such as hydrogenation,hydrothermal synthesis,thermal annealing,metal reduction and electric-field-controlled ionic liquid gating method.However,all the above reported methods slack the ability of fast synthesis,creation of high-concentration,and uniform vacancy distribution throughout the bulk,thus limiting the application in improving the properties of materials and devices.Considering the above critical challenges,in this paper,a method to create oxygen defects in oxide materials by coupling an electric field with thermal activation is presented.In contrast to reported methods,this strategy can create bulk distributed oxygen defects in a fast and simple way.Herein,an“oxygen vacancy percolation”model is presented,using SrAl₂O₄,a representation of ternary oxide system,as a subject.In this work,creating bulk distributed oxygen defects at a certain concentration with external field assisted processing methods of SrAl₂O₄,a long-persistent luminescence?LPL?material,are compared systematically,utilizing characterization methods like STEM and XPS.Combined with the first principles method,the character of temperature and electric field in oxygen vacancy generation and its distribution and migration is discussed.Luminescent performance of SrAl₂O₄ processed with an assisted field has improved significantly,as long as 90h,more than twice of the commercial materials.Meanwhile,adjusting the intensity of electric field can modify the concentration of oxygen vacancy in material,optimizing the performance of SrAl₂O₄.Combining characterizations like the spectrum of the thermoluminescence and first principles calculation,a proper depth and concertation of oxygen vacancy is pointed out to be the key of luminescent performance improvements.Using TiO₂,a representation of binary oxide,as a subject,a fast and efficient approach to produce TiO_2-x with a certain oxygen vacancy concentration under an auxiliary field presenting an outstanding lithium battery performance is analyzed with characterization methods such as spectrum.TiO_2-x as treated with auxiliary field processes a specific capacity up to 240 m Ah/g under a discharge rate of 0.2C,and a good stability after a long circulation.In order to further illustrate the universality and effectiveness of this method,SnO₂,Zn O and WO₃ are researched,exploring the introduction of oxygen vacancy under an auxiliary field,which causes changes in electronic structure,meaningful in further development and application.The field assisted approach this work researched brings possibilities to improve material properties in defect engineering,meaningful in many research areas.