Ordered W Vacancies In Tungsten Bronzes

Tungsten bronzes are a group of non-stoichiometric compounds.Due to their open structure,they have good electrical,optical,chemical and electrochemical superconductive properties.They have a wide range of application prospects,such as smart windows,electrode materials.This thesis includes two major parts shown as follows:1.The potassium tungsten bronzes with superstructures were synthesized by a simple heating method in this work.The atomic-scale information of superstructures was acquired by scanning transmission electron microscopy.The experimental results indicate that the superstructures in the potassium tungsten bronze are attributed to the ordered W vacancies in single atomic layer.Meanwhile,the ordered W vacancies disappeared under the e-beam irradiation.This work facilitates further understanding of the superstructures in potassium tungsten bronze and paves way for designing potassium tungsten bronze materials with better performance.2.The sodium tungsten bronzes with tunnel structure were synthesized by a simple heating method in this work.The triclinic Na5W14O44 phase in the product were characterized by electron microscopy.The phase transition occured from Na5W14O44 to hexagonal WO3 under electron beam irradiation.