Preparation And Crystallization Performance Study Of Rare Earth Doped Na₂O-ZnO-Al₂O₃-SiO₂ System Photothermal Refractive Glass Ceramics

Photo-Thermo-Refractive（PTR）glass is a type of silicate optical microcrystalline glass that achieves high transmittance and good photosensitivity and thermal sensitivity through precise doping of trace elements.Periodic refractive index changes can be formed inside the glass through corresponding optical and thermal treatments.Using this feature,some grating materials can be prepared,such as transmission Bragg gratings,reflection Bragg gratings,and chirped Bragg gratings.The PTR glass volume grating has significant application advantages in fields such as lasers,fiber optic communications,and holographic storage.It can be used for broadening and compression of ultrafast pulse lasers,improving output power and stability.It can also be used for beam steering,mode selection,linewidth narrowing,spectral beam combining,etc.of high-power solid-state lasers to achieve efficient and high-quality laser output.This article uses high-temperature melting method for glass preparation,with Na₂O-ZnO-Al₂O₃-SiO₂ system as the basis,determines the selection of raw materials in the glass,and explains the role of each raw material in the glass system,providing a theoretical basis for subsequent formula design.The selection of glass formula,the confirmation of the optimal exposure time,and the optimal thermal treatment system were studied as follows:（1）XRD,SEM,EDS,TEM,absorption spectrum,coefficient of thermal expansion,and refractive index were used to characterize the structure,morphology,composition,and optical properties of PTR glass.The best glass formula was selected based on experimental and theoretical basis.Through experimental and analytical tests,the optimal exposure time was determined,as well as the required processing temperature and time for the thermal treatment process（using the"three-step method"）.The best production process for PTR glass was analyzed and summarized.（2）The problem of yellow precipitation appearing at the surface of PTR glass due to wear was analyzed,and the reason for the yellow precipitation was confirmed.The method of glass surface ion exchange was used to solve the problem of yellow precipitation,and the optimal processing technology process was determined.（3）The influence of introducing potassium elements by external doping on the intrinsic properties of glass,nucleation performance,and crystallization performance was explored.It was found that with the increase of potassium element content,the expansion coefficient of the glass itself changed,and the softening temperature of the glass had an upward trend.The results showed that potassium elements can enhance nucleation ability,but excessive introduction can cause uncontrolled crystallization ability,ultimately leading to glass opacity.This article provides a certain theoretical guidance and experimental basis for the preparation and application of PTR glass.