Y₃Al₅O₁₂–SiO₂ Glasses: Structure and Polyamorphism

Abstract

Aerodynamic levitation and CO 2 laser melting have been used to synthesize the yttrium aluminosilicate glasses zY 2 O 3 -yAl 2 O 3 -xSiO 2 with z/y = 3/5 corresponding to the YAG (Y 3 Al 5 O 12 ) composition and x between~5 and~45 mol%. The low-and high-density (LDA inclusion and HDA matrix) polyamorphic phases in glasses with less than~14 mol% SiO 2 were identified with backscattering electron imaging. Polarized and depolarized Raman spectra show the formation of various Q n SiO 4 species whose relative populations change smoothly as the SiO 2 content is altered. The AlOs (s = 4-6) and YOz (z = 6-9) polyhedra formed in the YAG glass are preserved upon silica additions while the terminal oxygens of the Q 2 AlO 4 tetrahedra are gradually bridged to the Q n -SiO 4 species. The low-frequency Boson Peak overlaps with the vibrational spectrum and its maximum is redshifted with increasing silica content. Micro-Raman spectra measured for the LDA and HDA amorphous phases are found to be similar to the spectra of the bulk glass indicating common structural characteristics. The stability of the LDA phase against crystallization appears to be lower than that of the HDA phase. The crystallinity on certain inclusions consisted of YAG microcrystals and a new unidentified microcrystalline phase within Y 4 Al 2(1 -x) Si 2x O (9+x) solid solution.

A yttrium aluminosilicate glass fiber with graded refractive index fabricated by melt‐in‐tube method

“…The YAS glass network structure depends on the concentration of SiO 2. Therefore, as the Si concentration varies along the radial direction of the fiber cross section, an imaginary concentric circle structure (shown in Figure B) which is similar to the rings of tree is generated. Each circle stands for a specific local structure entropy.…”

“…Once used as the core material within a silica cladding and then drawn by MIT method, YAG crystal was proved to be eventually YAS glass . Although the element migration‐induced YAS core seems to be detrimental to the performance of optical fiber, thermal expansion coefficient and refractive index become more compatible owning to the excellent solid solubility of YAS glass . Moreover, the relatively high content of Al and Y of fiber core is capable to suppress the stimulated Brillouin scattering (SBS) and achieve a higher maximum doping concentration than the silica fiber .…”

The preparation of Yttrium Aluminosilicate (YAS) Glass Fiber with heavy doping of Tm3+ from Polycrystalline YAG ceramics

“…YAG ceramics have been the subject of intensive investigation over the past years due to their profound importance in optical applications, along with their outstanding physical and chemical stability . In recent years, many efforts were paid to the preparation of optical fibers with YAS glass core for optical applications and laser output have already been realized with different kinds of doped ions (Nd 3+ , Yb 3+ , Er 3+ ) . The relatively high content of Al and Y of the fiber core is beneficial to suppress the stimulated Brillouin scattering (SBS) and achieve higher doping concentration of rare earth ions than in the silica fiber .…”

Luminescence Behavior of GdVO4: Tb Nanocrystals in Silica Glass-Ceramics

“…Micro-Raman spectroscopes of samples and GdVO4 crystal were also tested and shown in Figure 1b. Several bands near 441, 495, 600, 800, and 1060 cm −1 can be seen in each sample, which can be assigned to the vibrational mode of SiO2 glass [24][25][26][27][28]. In addition, some vibrations were detected in the Raman spectra of xTGV(x = 0.1-0.4), which were located at 263, 380, 485, 820, and 880 cm −1 .…”