Studies On Structure And Properties Of Ta₂O₅/ZrO₂ Boron Based Special Dispersion Glasses

The special dispersion glass is a kind of optical glass which is far away from the optical "normal line",and has a large relative partial dispersion deviation value.It can be used as a lens material in the optical system to eliminate the secondary spectrum,which improves the imaging accuracy and reduces the system complexity.In order to enlarge the relative dispersion deviation of special dispersion glass,we need explore the law of "component-structure-special dispersion " to find structural factor that affects the special dispersion performance,which reveals more performance of special dispersion glass.The results of this paper are as follows:The effects of Ta2O5 and ZrO2 on structure and properties of Na2O-B2O3-SiO2 glass were investigated in detail.The specific dispersion properties are determined by the content of [BO3] in the glass.The field strength of Ta5+ and Zr4+ are both large,which easily destroys the original network structure in glass.This performance promotes the transition of [BO4] to [BO3],increasing the relative partial dispersion deviation of the glass.In addition,both Ta5+ and Zr4+ have high coordination numbers,which are present in the glass structure in form of [TaO6] octahedra and [ZrO4] hexahedron to enhance the glass skeleton with and [BO3] and [BO4].This behavior improves the glass production capacity and the physical and chemical properties.In this experiment,Ta2O5/ZrO2 boron based glass was prepared according to the change of B2O3 content,and the [BO3] which influences the relative dispersion deviation value is studied deeply.The study shows that [BO3] is divided into "ring" [BO3] and "loose" [BO3],"ring" [BO3] exists in the network and connected to other atoms through the bridge oxygen bond.The relative dispersion deviation is determined by the content of "ring" [BO3] in glass.In addition,the crystallization performance of Ta2O5/ZrO2 boron based glass was calculated.Both Ta2O5 and ZrO2 have high field strength and can act as nucleating agents to produce heterogeneous nucleation sites,which increases phase separation in glass and promote crystallization.[TaOn] clusters gradually formed as nuclei in glass network to enhance the NaTaO3 crystallization of glass;Zr4+ filled glass network gap and attracting anionic aggregation,which promotes phase separation and ZrO2 crystallization.Both of the crystallization methods are surface crystallization.Finally,the formation mechanism and structural characteristics of Pt point in glass of Ta2O5/ZrO2 boron based glasses were studied.The high content of Ta5+ and Zr4+ results in the lower viscosity and higher corrosion Pt crucible.The presence of oxygen in the glass component and the atmosphere in the molten atmosphere is transferred to the surface of the Pt crucible by diffusion to form Ptn+,which is dissolved by diffusion to the glass melt.When the melt is cooled,Ptn+ ions condense and grow to form Pt point.Pt point exists mainly as triangle and hexagonal.The size of the Pt point is below 20 μm.The special dispersion glass with large deviation from the value has been obtained through the adjustment of composition.The law of "component-structure-special dispersion performance" is revealed deeply.The glass components can be adjusted according to the special dispersion deviation value so that the special dispersion glass can get wider application in optical glass field.