大尺寸新型无网络形成体氧化物光学玻璃的制备与超塑性烧结机理

Oxide glasses lacking network formers (i.e., silicon, boron oxide and phosphorus pentoxide) have potentially broad application in the fields of laser light and imaging since they possess superior optical properties such as higher refractive index. But under the conditions of conventional melting-solidification methods, they are prone to crystallize due to low glass-forming ability. Through special processes such as containerless solidification, only small amorphous products within millimeter scale can be obtained, which severally limits the application of these new glasses. To solve this problem, we proposed a new route to fabricate centimeter-sized TiO2-based and Nb2O5-based glasses, which adopt hot-press sintering of amorphous oxides by using the superplasticity of supercooled glass liquid in the supercooled liquid region. By doping rare-earth ions into these new oxide glasses, large-sized upconversion glass with high efficiency can be achieved. In this project, the effects of composition and rare-earth doping on thermal stability of amorphous samples were systematically investigated. In addition, the dynamic process of superplasticity deformation of glasses during hot-press sintering was analyzed. Furthermore, effects of type and size distribution of as-prepared raw glass materials and heat treatment parameters (temperature, dwell time, heating rate, etc.) on the consolidation density and optical properties of ultimate bulk glasses were also studied. Finally, the superplasticity consolidation mechanism was clarified based on fore-mentioned analyzation. We believe that the study of this project could provide theoretical guidance to fabricate large-sizedly new optical glasses by using a low-pressure, modest-temperature and fast preparation route.

不含SiO2、B2O3、P2O5等传统网络形成体的TiO2基、Nb2O5基新型氧化物块体玻璃具有超高折射率等优异光学性能，在激光、显像等领域具有广阔的应用前景。但传统的熔化-凝固方法会导致析晶，无容器凝固等特殊制备方法只能得到毫米级及以下非晶产物，严重制约着该类新兴材料的应用。本项目提出利用非晶态物质在过冷液相区内的超塑性进行热压烧结实现大尺寸制备的创新思路，有望获得厘米级TiO2基、Nb2O5基玻璃，进而通过掺杂稀土离子制备高转换效率的大尺寸上转换发光玻璃。通过系统研究不同组分配比以及稀土掺杂后非晶的稳定性变化规律，深入分析热压烧结过程中非晶的超塑性变形动态过程，以及非晶原料种类、粉末粒径、热压烧结温度、保温时间、热压压力等因素对最终光学玻璃的致密度和光学性能的影响，深入揭示新型氧化物玻璃的超塑性烧结机理，为该类材料的大尺寸化制备提供低压、中温、快速的温和制备路线和理论指导。

不含SiO2、B2O3、P2O5等传统网络形成体的TiO2基、Nb2O5基新型氧化物块体玻璃具有超高折射率等优异光学性能，在激光、显像等领域具有广阔的应用前景。但传统的熔化-凝固方法会导致析晶，无容器凝固等特殊制备方法只能得到毫米级及以下非晶产物，严重制约着该类新兴材料的应用。本项目提出利用非晶态物质在过冷液相区内的超塑性进行热压烧结实现大尺寸TiO2基、Nb2O5基玻璃制备的创新思路。首先，利用无容器凝固技术成功制备了高质量的La2O3-TiO2-SiO2、La2O3-Nb2O5球形非晶玻璃材料，系统研究了添加不同含量SiO2对基体材料的过冷液相区宽度∆T和折射率的影响规律；进而利用 La2O3-Nb2O5 氧化物玻璃在过冷液相区内的超塑性，用热压烧结法在温度、压力等温和制备条件下实现大尺寸La2O3-Nb2O5非晶氧化物玻璃的快速热压烧结；进一步，利用热压烧结法制备了La2O3-TiO2-SiO2(LTSO)和La2O3-TiO2-ZrO2(LTZO)氧化物玻璃，研究了烧结温度、烧结压力等工艺参数对烧结过程的影响，通过成分的调控和热处理工艺的优化，热压烧结得到的大尺寸LTSO和LTZO非晶材料具有超高的折射率，表现出优异的光学性能；最后，用无容器凝固技术得到了完全非晶的74%Al2O3-26%Y2O3（AY26）球形非晶玻璃材料，并进一步用热压烧结法获得了大尺寸无色透明的AY26玻璃，对AY26玻璃进行晶化获得了包含Y3Al5O12相和Al2O3相的、由纳米尺度晶粒组成的透明陶瓷材料，开拓了无容器凝固-非晶晶化在在制备纳米陶瓷材料方面的应用。以上工作共发表论文17篇，其中SCI收录15篇，包括Nature Communications等高影响力期刊；申请专利2项，授权1项，其中包括国际专利1项。