Spray‐Dried TiO₂(B)‐Containing Photocatalytic Glass‐Ceramic Nanobeads

Abstract

Glass‐ceramic nanospheres of molar composition 0.83 SiO2 · 0.17 TiO2 are produced by the sol‐gel spray‐drying method followed by controlled heat treatments up to 1200 °C. TiO2(B) and anatase nanocrystals are precipitated in the glassy matrix: the latter phase gradually predominates with increasing ceramization temperature and time, in parallel to an overall increase in crystal sizes. The nanospheres exhibit evident photocatalytic activity under UV‐A irradiation, especially at annealing stages involving a comparatively higher amount of TiO2(B) and smaller crystals. The occurrence of TiO2(B) in this simplified binary glass‐ceramic material underlines the key role of this phase in the dynamics of crystallizing TiO2‐bearing silicate melts.

Spray‐dried sol‐gel glass‐ceramic powders based on the tunable thermal expansion of quartz and keatite solid solutions

“…31 Suitable amounts of LiNO 3 and Al(NO 3 ) 3 ·9H 2 O (≥98.5%, Merck) were then solved 1:1 in deionized water and added to the first solution under constant stirring, further diluting it with deionized water to 5 wt% equivalent total oxide content. As similarly detailed elsewhere, 30 50 ml of the so-obtained mixture were then spray-dried in 2 h to obtain ~2 g of amorphous nanobeads. The solution was thereby nebulized by an aerosol atomizer (Atomizer, AGK 2000, Palas) operated with pressurized air (2.9 bar) into a tube furnace set at 500°C.…”

“…The initial glassy nanobeads were likely to contain some residual water and organics even after a calcination at 500°C, as observed previously in spray-dried SiO 2 -TiO 2 glassceramics. 30 This volatile content may have effectively lowered glass viscosity, facilitating the initial stages of crystallization and sintering and causing the grain coarsening and agglomeration documented by TEM (Figure 1). Concurrently, we employed an excess of Li 2 O to foster the crystallization of the samples into Qss and to suppress the formation of cristobalite, as documented in the past 31 ; please note that we demonstrated that Li 2 O volatilization F I G U R E 4 Excerpts of the X-ray diffraction measurements performed at high temperature and at cryogenic conditions, manifesting the high-low inversion of quartz solid solution in samples: (A) LA00, (B) LA05, (C) LA10, (D) LA15, (E) LA19, (F) LA21, (G) LA22, (H) LA25.…”

“…Studies o derived SiC ceramic 25 and SiC/SiC c shown that porosity decreases and mecha prove with the increasing number of PIP show that increasing pyrolysis temperatu tration of SiC fillers in polycarbosilane improved mechanical properties in two-d SiC (C/SiC) composites fabricated using Starting with pyrolysis of a "cured prepreg-based composite, each processin process involves infiltration of a precera porous ceramic preform followed by a py which the polymer is converted into ceram cess modeling is focused on these two ste Modeling of infiltration of liquids in well-studied subject, especially in the where it is used to model seepage of wa soils and rocks. 29,30 The physics of resin under pressure is similar to the seepage pr lar approaches have been used also to mod into a mold containing fiber mats. 23,[31][32][33][34][35][36][37][38] T in these cases to determine the resin flow ing times corresponding to different infilt Preceramic polycarbosilane polymers as precursors to make ceramic fibers 10,3 trix.…”

“…Modeling of infiltration of liquids in porous media is a well-studied subject, especially in the field of hydrology where it is used to model seepage of water through porous soils and rocks. 29,30 The physics of resin flow into a mold under pressure is similar to the seepage problem and so similar approaches have been used also to model the flow of resin into a mold containing fiber mats. 23,[31][32][33][34][35][36][37][38] The models are used in these cases to determine the resin flow front and mold filling times corresponding to different infiltration conditions.…”

Thermal Conductive Networks Constructed by Sialon Fibers in-Situ Synthesized in Barium Aluminosilicate Glass-Ceramic

“…In these cases, glass-ceramic material has attracted great attention as a promising material for high temperature structural matrix [8,9]. Compared with other ceramic materials, glass-ceramic material has the advantages of better thermal stability, lower coefficient of thermal expansion [10][11][12]. Barium aluminosilicate (BaAl2Si2O8, BAS) is an advanced glass-ceramic material known for the excellent high temperature stability.…”