锂铝硅系玻璃陶瓷晶化行为研究

Crystallization behavior study on the Li_2O-Al_2O_3-SiO_2 system glass-ceramics

配合料MgO-ZnO-Li2O-Al2O3-SiO2于1550℃熔融2h,经两步及三步热处理工艺控制成核及晶体生长。采用DTA、XRD、SEM、FT-IR和紫外-可见-近红外分光光度计对材料进行表征。六面体填隙!-锂霞石固溶体于840～960℃析出,960℃开始发生晶型转变,1100℃下!-锂霞石固溶体转变为四面体!-黝辉石固溶体。根据XRD结果计算出六方!-锂霞石晶体的晶格参数为"(0.5145±0.0006)nm,c(0.5475±0.0004)nm,四面体!-黝辉石晶体的晶格参数为"(0.74836±0.0003)nm,c(0.90585±0.0007)nm。几乎全部铝原子进入!-锂霞石六配位体中,而只有少量的六配位铝原子存在于残余玻璃相中。所有铝原子未进入到!-黝辉石四面体结构,在残余玻璃相中多以六配位形式存在。粒径为15nm左右的!-锂霞石玻璃陶瓷在可见光波长范围内透过率达85%。

The batch containing MgO-ZnO-Li2O-Al2O3-SiO2 was melted in a platinum crucible at 1 550 ℃ for 2 h and then two- or three-step heat-treatment processes for the nucleation and crystal growth. The characterizations were performed by differential thermal analysis, X-ray diffraction, Fourier transmission infrared spectroscopy, scanning electron microscopy and UV-Vis-NIR scanning speetrophotometer. The hexagonal stuffed β-eueryptite solid solution （SS） crystallizes at 840-960 ℃. Nearly all of the hexagonal β-eueryptite SS transforms into the tetragonal β-spodumene SS at 1 100 ℃. The lattice parameters of β-eueryptite SS are ct=（0.514 5±0.000 6） nm,c=（0.547 5±0.000 4） nm, the lattice parameters of β-spodumene SS are α= （0.748 36i-0.000 3） nm,c=（0.905 85±0.000 7） nm. Almost all of the aluminum atoms enter into the tetrahedral sites in the aluminosilieate network of the β-eueryptite. All of Al atoms do not belong to the aluminosilieate network of the β- spodumene SS. The transmittance of the β-eueryptite glass-ceramic with a mean grain size of 15 nm reaches 85% in the visual light wavelength.