Effect of carbon on the co-presence of metallic tungsten as a nucleation agent and Eu²⁺ in glass: crystallization of CaO–Al₂O₃–SiO₂ glass probed with Eu²⁺ luminescence

Abstract

Effect of carbon on the co-presence of metallic tungsten (W) as nucleation agents and Eu2+ ions as a probe for tracking crystallization in CaO–Al2O3–SiO2 (CAS) glass was demonstrated by efficient reduction method of Eu2+ and metallic W.

Effect of Vanadium Oxide on the Crystallization of CaO–Al2O3–SiO2 Glass

“…Figure shows XRD patterns for the glass specimens. The profiles for Product-A to -E and -H, all of which fit well with those reported in our previous studies, − exhibit reflections attributed to metastable CaAl 2 Si 2 O 8 crystals with layers stacked in the c -axis direction . In addition, reflections attributed to calcium vanadate were absent in all the profiles.…”

“…Figure shows SEM images of the galss specimens. All the SEM images display a cross-section of a house-of-cards structure similar to those reported previously. − In addition, the volume fraction did not greatly differ between Product-A, -B, and -C. The difference between Product-D and -E also followed a similar trend. Although needle-like particles in Product-H are not clearly observed compared with Product-A to -E, the Vickers hardness for Product-H is 4.1 ± 0.3, which is close to the value of 4.2 ± 0.3 obtained for CAS GC-H, which has been often denoted as a standard in our previous reports. − …”

“…The volume fractions for the heated glass specimens were approximately estimated by analysis of binarized SEM images. As in our previous studies, − SEM images of house-of-cards structures comprising platy particles of metastable CaAl 2 Si 2 O 8 appeared as black regions with needle-like particles that represent an arbitrary cross-section of platy particles in a house-of-cards structure. We thus tentatively denoted the needle-like particles as platy particles of metastable CaAl 2 Si 2 O 8 whose size was defined as the longitudinal length, the lateral size of platy particles. − The aspect ratio , is also defined as the ratio of the lateral size to the thickness, which represents the shorter dimension of the needle-like particles (lateral size/thickness).…”

“…The glass specimens were prepared according to our previous reports; − the melting conditions were 1550 °C for 1 h under air in an alumina crucible. Batches were prepared by mixing CaCO 3 , Al 2 O 3 , and SiO 2 to form 50 g of 25CaO–20Al 2 O 3 –55SiO 2 glass (wt %) with 0.0, 0.025, or 0.050 wt % MoO 3 , 0.08, 0.2, or 0.4 wt % C, and 0.0, 0.052, 0.21, 0.52, or 1.0 wt % V 2 O 3 .…”

“…Following the discovery of glass-ceramics (GCs), composite materials in which a crystalline phase is present within a glassy phase, which were initially prepared using silver nanoparticles as nucleation agents, GCs with varied compositions, crystals, and microstructures have been widely investigated to explore their fundamental properties for practical applications. − Thus, nucleation agents such as titania and zirconia that dominate bulk crystallization can be essential. − Among multiple nucleation agents, metallic Mo and W particles are the best candidates to control the microstructure of CaO–Al 2 O 3 –SiO 2 (CAS) GCs with precipitated hexagonal platy particles of metastable CaAl 2 Si 2 O 8 (CAS-GC-H), a layered crystal, in the 3–110 μm range. − In addition, this particle size control was achieved by the single composition of parent glasses and the same heating conditions without byproduct formation. − Although the volume fraction of CAS GC-H is relatively low − and can be a drawback to separately characterize glassy and crystalline phases, the mechanical properties induced in CAS GC-Hs by the house-of-cards structure formed by layered crystals similar to those of mica were recently analyzed using X-ray computed tomography . The microstructure of CAS GC-Hs is therefore worth further controlling to elucidate the mechanism of mechanical properties.…”