Rapid preparation of low thermal expansion transparent LAS nanocrystalline glass by one-step thermoelectric treatment

EFFECT OF CRYSTALLISATION TEMPERATURE ON LAS TRANSPARENT GLASS-CERAMICS CONTAINING A HIGH Al₂O₃ CONTENT

“…The calculated average crystal size is shown in Table 1. The values were shown to be different from the SEM results, because the formula calculates the size of the aggregate crystals, which is significantly larger than that observed microscopically [14]. The accumulation of crystal particles in the C-840 glass matrix increased the internal voids [13], a large number of voids in the glass phase were filled by the accumulation of precipitated crystals from the C-860 sample, and the arrangement and distribution were tighter than the previous samples [4].…”

“…In the ultraviolet range, all the samples have strong absorption. The ultraviolet absorption of the glass-ceramics is related to the amount of bridging oxygen in the residual glass phase, the lower the bridging oxygen, the more the absorption limit wavelength increases [14]. It showed that an increased crystallisation temperature reduces the degree of polymerisation of the glass network, where the number of bridging oxygen atoms are decreased in the residual glass phase.…”

“…In this system, TiO 2 and ZrO 2 were the nucleating agents, many nanocrystals were formed during the nucleation process [20]. TiO 2 , ZrO 2 and ZrTiO 4 were first formed during the heat treatment process, and the crystals grew in the enrichment zone [14,21,22]. For the C-780 sample, the largest size of crystals of about 10 nm was observed.…”

“…Kumar et al [13] prepared LAS glass-ceramics with a visible light transmittance of more than 80 %, but its thermal expansion coefficient showed a negative expansion only in the low temperature range, and the Al 2 O 3 content was 25 wt.%. Zhang et al [14] prepared a low-expansion transparent LAS nanocrystalline glass with a transmittance of 85 % (thickness of 1.2 mm) via thermoelectric treatment, and the Al 2 O 3 content was 24 wt. %.…”