Study Of The Structural Characteristics And Chemical Stability Of Zinc Phosphate Glass

Phosphate glass has the characteristics of low melting temperature,ultraviolet transmission,low dispersion,and has potential application value in laser glass,sealing glass,and solidification of nuclear waste glass.However,poor chemical stability limits the application of phosphate glass in these areas.Zinc phosphate glass is often used as a matrix material for low-temperature sealing glass and laser glass and is susceptible to hydration in the environment during use.In this paper,the structural characteristics of the zinc phosphate glass material and its chemical reaction mechanism in the water environment were studied using experimental methods,which provided a reference for exploring the structure of zinc phosphate glass and its chemicalstability.50ZnO-50P₂O₅zincphosphateglassmatrixand xGd₂O₃–?50-x?ZnO–50P₂O₅ and xLa₂O₃–?50-x?Zn O–50P₂O₅ glass were prepared by melt-quenching method.XRD,SEM,FT-IR,Raman and DSC analysis techniques were used to study the formation range,surface morphology,microstructure and thermal stability of the glass;immersed glass samples were tested by comparing the samples before and after the immersion test.The phase,microstructure and microstructure of the micro-zones were discussed.The effects of water environment on the structure and stability of the glass network were discussed.The results indicated:1.The glass formation range of xGd₂O₃–?50-x?ZnO–50P₂O₅ glass is 0?x?8mol%,and the glass formation range of xLa₂O₃–?50-x?ZnO–50P₂O₅ glass is 0?x?10mol%.The density of the system zinc phosphate glass increases with the replacement of ZnO by Gd₂O₃ or La₂O₃?from 2.9026 g.cm^-33 for Gd0 and La0 to 3.3184 g·cm^-33 for Gd8 and 3.40926 g·cm^-33 for La10?.The molar volume of the phosphate glass sample gradually increased(increased from 38.47109 mol·cm^-33 of Gd0 to 40.42759 mol·cm^-3of Gd8,and 38.47109 mol·cm^-33 of La0 to 39.92275 mol·cm^-33 of La10),indicating that with the introduction of Gd₂O₃ and La₂O₃,the phosphate glass becomes more dense and more open chain structures appear in the phosphate glass network structure.2.The structure of phosphate network in glass of xGd₂O₃–?50-x?ZnO–50P₂O₅and xLa₂O₃–?50-x?ZnO–50P₂O₅ system is mainly Q² structural unit,and contains a small amount of Q¹ and Q⁰ structural units.With the increase of the content of Gd₂O₃and La₂O₃,the content of Q² structural unit decreases,the Q¹ structural unit increases,and the system gradually converts from metaphosphate to pyrophosphate.3.Gd₂O₃ and La₂O₃ can improve the anti-crystallization ability of zinc phosphate glass.With the increase of Gd₂O₃ and La₂O₃ content,the glass transition temperature?T_g?andthecrystallizationtemperature?T_c?of xGd₂O₃–?50-x?ZnO–50P₂O₅ and xLa₂O₃–?50-x?ZnO–50P₂O₅ glass would increase,but?T would decrease.4.The microscopic network structure of zinc phosphate glass wouled be destroyed by the hot water soaking.The zinc phosphate glass matrix and glass samples containing Gd₂O₃ and La₂O₃ had obvious chemical reactions after soaking in hot water.Water molecules and phosphate glass network structure unit ion exchange reaction and hydrolysis reaction,generate HPO₄^2-.Zn²⁺and HPO₄^2-reacted,and?ZnHPO₄?₂·3H₂O and Zn₂P₂O₇·3H₂O were formed in the system.The reaction time increased,and?ZnHPO₄?₂·3H₂O was transformed into Zn₂P₂O₇·3H₂O crystal.La³⁺and Gd³⁺participate in the chemical reaction and GdPO₄·H₂O and La PO₄·0.5H₂O crystals are formed.