Preparation Of Hexacyanocobalt-tri-silver Complex And Its Negative Thermal Expansion Properties

Negative thermal expansion materials were discovered as early as the 1930s,but it was not until 1996 that Sleight et al.published on ZrW₂O₈ with a negative thermal expansion property in the temperature range of 0.3K¹050K in"Science",which caused scientists to negatively thermally expand materials.attention.The negative thermal expansion material is a relatively advanced functional material,which has a completely different negative thermal expansion coefficient from the normal state,and thus has broad application prospects in the fields of aerospace,information,new energy,transportation and the like.In particular,metal-organic framework structural materials may have a large negative thermal expansion coefficient based on the special versatility of the metal center and the unsaturated characteristics of the metal sites,so that gas storage and separation,catalyst,optical and electrical,magnetic Learning,drug transmission and other aspects have strong application potential and practical value.In this paper,the negative thermal expansion properties of negative thermal expansion Ag₃[Co?CN?₆]materials are investigated.Using AgNO₃ and K₃[Co?CN?]₆as reactants,,the milky white negative thermal expansion Ag₃[Co?CN?₆]material was prepared by ordinary solution method,and the molar ratio of the reactants,stirring temperature,drying temperature,The influence of material morphology and other factors on the thermal expansion coefficient of Ag₃[Co?CN?₆]material?Ag₃[Co?CN?₆]powder was prepared by ordinary precipitation method,and Ag₃[Co?CN?₆]film was successfully prepared on the surface of copper and aluminum sheet stainless steel,using SEM,XRD,XPS,TEM,TMA chemical composition of Ag₃[Co?CN?₆]powder and film were characterized by equipment such as contact angle measuring instrument.The ratio of metal ions to organic ligands has an important influence on the growth of metal skeleton structural materials.The analysis of microstructure data shows that the coordination ability of carboxyl ligands is significantly different at high temperature and normal temperature,and the coordination mode is also different,which results in the powder material having superior negative thermal expansion properties than the film material.It is found that the negative thermal expansion of negative thermal expansion Ag₃[Co?CN?₆]material is superior to other negative thermal expansion materials,and the negative thermal expansion coefficient is larger.In the temperature range of-38 to 130°C,a-axis and b-axis,c The average coefficient of thermal expansion of the shaft is aa=127.18×10^-6K^-1,ab=127.18×10^-6K^-1and ac=-114.36×10^-6K^-1,respectively.