Preparation and Structure of New Oxyfluoride Glass‐Ceramics Containing BaLiF₃ Nanocrystal

Abstract

Through a careful composition design, new oxyfluoride glass‐ceramics (GCs) containing BaLiF3 nanocrystals with sizes of around 30 nm were prepared. Microstructural characterizations show interpenetrating phase separation in the sample with a composition of 15BaF2–15ZnF2–70SiO2, after thermal treatment at 580°C for 40 h which leads to the nanocrystallization of BaLiF3. The BaLiF3 nanocrystals embedded in the glassy matrix could provide Ba or Li sites for the incorporation of optically active rare earth and transition‐metal ions, which provides a possibility to explore novel photonic properties by the codoping of rare earth and transition‐metal ions in GC materials.

The Transformation from Translucent into Transparent Rare Earth Ions Doped Oxyfluoride Glass‐Ceramics with Enhanced Luminescence

“…Both [SiO 4 ] and [AlO 4 ] domains in the surface layer were etched by HF acid, so that the contrast between the fluoride‐rich phases (see the white domains in Figure 2a) and the remaining silica‐rich phases (see black domains) can be seen. [ 27 ] Flower‐like Ba 2 LaF 7 crystals (180–190 nm) are distributed in the fluoride‐rich phases. Ba 2 LaF 7 crystals grow to ≈220 nm and the tiny spherical Ba 2 LaF 7 nanocrystals (≈5 nm) precipitate from the fluoride‐rich phase upon HT at 600 °C for 4 h (Figure 2b).…”

“…The relaxation delay of 19 F in all the samples was 4 s. The 19 F chemical shifts were referenced to CFCl 3 , using AlF 3 (δ = -172.5 ppm) as a secondary standard. 27 Al MAS NMR spectra were obtained at the resonance frequency of 130.2 MHz, operating with a 2.5 mm MAS probe at a spinning rate of 12 kHz. The typical pulse length was 0.7 μs (10° liquid flip angle).…”

“…The relaxation delay was 0.5 s for all the samples. The chemical shifts of 27 Al were referenced to Al(NO 3 ) 3 (1 m) aqueous solution. 29 Si MAS NMR spectra were acquired at the resonance frequency of 99.3 MHz using a 4 mm MAS probe at a spinning rate of 6 kHz.…”

“…To reveal the structural evolution during HT, we performed the 27 Al, 29 Si, and 19 F magic angle spinning (MAS) NMR measurements on both P-GC and the heat-treated P-GC samples (Figures 4a-c). It is seen in Figure 4a that 27 Al MAS NMR spectra of all the samples feature the main resonance at ≈60 ppm, which is attributed to four-coordinated aluminum (Al(IV)). Al 3+ ions primarily exist in [AlO 4 ] tetrahedra besides a minor amount of [Al(O,F) 4 ].…”

Composites based on titanium alloy Ti–6Al–4V with an addition of inert ceramics and bioactive ceramics for medical applications fabricated by spark plasma sintering (SPS method)

“…The diffractogram of the composite containing 40 wt% Al 2 O 3 revealed the presence of an Al 2 O 3 phase that crystallizes in a trigonal lattice with the following parameters a = b = 0.475 nm, c = 1.299 nm and spatial group R3c. Composites with the content of 40 wt% ZrO 2 modified with 8 wt% Y 2 O 3 contain Zr 0,92 Y 0,08 O 2 , Y 2 O 3 (TiO 2 ) 2 phases (also found in [14,15]) and Zr 3 O that crystallizes directly in tetragonal, face-centred cubic and trigonal lattices, with the parameters: Zr 0,92 Y 0,08 O 2 : a = b = 0.361 nm, c = 0,517 nm and spatial group P42/nmc, Y 2 O 3 (TiO 2 ) 2 a = b = c = 1.009 nm and spatial group Fd3m, Zr 3 O: a = b = 0.563 nm, c = 1.559 nm and spatial group R3c. The same phases were revealed in the case of specimens containing 80% of addition of ceramic phase, which has been demonstrated in previous studies [16].…”