Mechanical And Dielectric Properties Of Phosphate Glass Ceramics

Phosphate glass and glass ceramics have many unique properties compared with traditional silicate glass.In recent years,phosphate glass and glass ceramics have become one of the main research objects in many fields such as new energy,medicine,laser amplifier,optical（electronic）components and nuclear waste solidification.The glass in the Na₂O–BaO–TiO₂–P₂O₅ system was prepared by the conventional quenching route.The glass transition temperature（T_g）,onset crystallization temperature（T_c）and crystallization peak temperature（T_p）of all glass samples were determined by DSC.The optimal nucleation temperature and nucleation time of the glass were determined by these parameters,and the glass was crystallized at different temperatures.The structure of the glasses and glass-ceramics was analyzed by XRD,Raman and SEM.We measured the mechanical properties and dielectric properties of glass and glass ceramics by measuring microhardness,fracture toughness,density and dielectric parameters.The measurement results indicated that with the increase of phosphorus content,the glass structure tends to be compact,the micro-hardness and fracture toughness increase,and the dielectric constant decreases.The results in glass-ceramics indicated that with the increase of crystallization temperature,the microhardness,density,dielectric constant and dielectric loss of the samples with the appearance of the second phase would decrease,and the fracture toughness would change in the opposite direction.Based on the Na₂O–BaO–TiO₂–P₂O₅ phosphate glass,the glass and glass-ceramics with boron oxide were prepared.The effects of boron oxide content on the structure and properties of glass and glass-ceramics were discussed.With the increase of B₂O₃ content,a new network structure is formed in the glass and the thermal stability and mechanical properties of the glass are improved.The effect of 2 mol%B₂O₃ content on the dielectric constant of the glass is the most obvious,and the dielectric loss increases with the increase of B₂O₃.The addition of boron oxide hinders the formation of the original crystal phase and generates a new crystal phase with higher formation temperature.The changes in mechanical and dielectric properties of the samples are based on the changes in the content of two different crystalline phases at different crystallization temperatures.Considering the changes in the properties of glass and glass-ceramics,phosphate glass with 2mol%boron oxide content and glass-ceramics after crystallization at 680°C have relatively excellent comprehensive properties.